Articles & Info
What is Carbon Monoxide (CO)?
- CO is a colorless, odorless, tasteless gas
- It is a by-product of incomplete combustion (unburned fuel such as gas, oil, wood, etc.)
- Low concentrations of CO can go undetected and can contribute to ongoing, unidentified illnesses. At high concentrations, it can be deadly.
Why is it Dangerous?
If there is CO in the air you breath, it will enter your blood system the same way oxygen does through your lungs. The CO displaces the oxygen in your blood, depriving your body of oxygen. When the CO displaces enough oxygen, you suffocate.
What are the Symptoms?
Continued exposure or high concentrations can result in –
- Severe headaches
- Cardiac problems
- Breathing difficulties
- Brain damage
Long term exposure to low concentrations –
- Slight headaches
- Shortness of breath with only moderate exertion
- Dizziness and confusion
Why is it called "The Great Imitator"?
- Symptoms of CO poisoning are very similar to the flu
- Illness in pets preceding illness in a family member may suggest CO poisoning
Who is at Greater Risk?
- Senior citizens
- Unborn babies
- People with respiratory or coronary problems
- Pregnant women
- Young children
Note: Vulnerable people who are exposed even to low levels of CO for long time periods may have similar health affects as those exposed to high concentrations of CO.
What can Produce CO in our Homes
Anything that burns fuel or generates combustion gases including -
- Gas Stoves
- Space heaters
- Water heaters
- Portable generators
Solid fuels, such as wood, always produce carbon monoxide when they are burned. Gas and liquid fuels may produce no CO or very little.
What are the most common sources of Carbon Monoxide?
1. Automobile exhaust in attached garages.
This is responsible for 60% of all CO alarms. People who warm their cars up in the garage are trapping CO inside the garage. The CO can find its way into the home.
2. Gas cooking appliances.
This is reported to account for 20% of CO alarms. It may be a result of a misused, poorly maintained, poorly installed, or unvented cooking appliance.
3. Poor draft/venting for fuel burning appliances.
This is one of the most common and serious causes for CO build-up and has been reported to account for up to 19% of CO alarms. The products of combustion are not being safely expelled to the exterior. This could be due to venting problems, such as blocked chimney flues or inadequate venting for appliances or fireplaces. Other problems include poor installation and negative air pressure in the house, causing backdrafting, often due to exhaust fans.
Other problems include poor combustion at furnace. Inadequate combustion air to the furnace can result in incomplete combustion. If the furnace has a cracked heat exchanger, it is possible to get CO into the circulating air. It is also imperative that we do not deprive our heating equipment and fuel burning appliances of air; especially in air-tight homes where running exhaust fans can result in a shortage of combustion air. Combustion air is essential for safe operation of furnaces, water heaters, and other fuel burning equipment.
There can also be a leak in a chimney or flue pipe.
Ventilation issues are very common as a result of barbecues or gasoline powered equipment operating in an attached garage, basement, or enclosed area.
Are there more problems with carbon monoxide today than 30 years ago?
Yes, this is due to:
- More energy-efficient, air-tight homes
- Less natural ventilation
How can I guard against carbon monoxide poisoning?
The first line of defense is to have your home heating systems, fuel burning appliances, flues and chimneys checked and/or cleaned annually.
Here is the inspection checklist. Specialists should check for:
- Blocked openings to flues and chimneys
- Cracked, rusted, or disconnected flue pipes
- Dirty filters
- Rusted or cracked heat exchanger
- Soot or creosote build-up inside fireplaces and chimney flues
- Exhaust or gas odors
- Attached garages require gas proofing and automatic closers for doors into the home
- Adequate combustion air
- Adequate venting on indoor combustion appliances (i.e-gas stoves)
The second line of defense is a CO detector.
Carbon Monoxide Detectors
It’s a relatively new technology introduced in the early 1990s. It is designed to warn homeowners when CO reaches dangerous levels within the home.
How do they work?
CO detectors sample the air at specific time intervals. A microchip inside the detector stores the reading and keeps track of the level of CO that the detector is exposed to over time
Types of sensors:
- Biometric (Oldest type of sensor)
- Metal Oxide Semi-conductor
- Electrochemical (The best of the three types for a residential sensor)
- Infrared – Highly advanced, very expensive. Not something you would find at a typical hardware store.
The detectors are supposed to sound an alarm when exposed to a set level of CO (measured in parts per million) over a specific time period. These levels or standards are set by UL (Underwriters Laboratories).
Old Standard (Units manufactured between October 1, 1995 and October 1, 1998) - First Generation CO detectors.
To a low level for a prolonged period of time
Alarm after 30 days
To a low level of CO for an extended period of time
Alarm within 90 minutes
To a moderate level of CO for a shorter period of time
Alarm within 35 minutes
To a high level of CO for a short period of time
Alarm within 15 minutes
The UL Standard was revised and any detector manufactured after October 1, 1998 must conform to the new Standard.
To a low level for a prolonged period of time
Alarm after 30 days
To a low level of CO for an extended period of time
Alarm within 189 minutes
To a moderate level of CO for a shorter period of time
Alarm within 50 minutes
To a high level of CO for a short period of time
Alarm within 15 minutes
Also included in the new Standard is:
- CO detector should ignore a CO level reading of 70 for at least 1 hour without alarming
- CO detector should ignore a CO level reading of 150 for at least 10 minutes without alarming
- Must only signal under alarm or trouble. No low-level warning signal is allowed
- Must have a SILENCE button to shut it off. Must re-alarm after 6 minutes if CO levels persist
- Must meet the specificity test referencing non-alarm status at specific concentrations of certain gases and vapors
To put levels into perspective:
CO Level (ppm)
Maximum outdoor air quality level as per EPA
Maximum concentration for a continuous exposure in an 8-hour time period (OSHA standard)
Headaches in 1 to 2 hours, life threatening after 3 hours
Nausea and convulsions, death within 2 hours
Nausea within 20 minutes, death within 1 hour
Death within 1 to 3 minutes
Note: These studies are generally done on young, healthy people. These symptoms can change drastically depending on age, sex, weight, habits (e.g. smoking), and most importantly, your health.
- Reliability of the detectors
- CO detectors are supposed to alarm at certain levels as indicated in the tables above
- Recent testing suggests that many of these devices are not nearly as reliable as they should be
- There has been regular television coverage that focused on false alarms and the reliability of CO detectors
- In 1994, Chicago was the first major city to make these detectors mandatory in the living space
- In the last three months of 1994, the Chicago Fire Department responded to 8,600 CO alarms
- In almost every case there was no dangerous level of CO found during follow-up investigations
- Laboratory testing was done
- Up to 1/3 of the alarms tested, failed to alarm
- Technology for residential CO detectors is very primitive.
- Industrial detectors have a different set of standards and more sophisticated technology. As a result, they are very expensive.
- Different detectors have large variances on the levels at which they are supposed to alarm. The sensor technology used in home alarms is not designed to measure and display low level, short term concentrations of CO. Substantial differences exist in the sensitivity of different sensors at low levels. As a result, they may go off too soon or not soon enough.
- Standards require these devices to be tested at a humidity of 50%.
- Testing revealed that many devices failed to respond when humidity levels were low even though they are supposed to work within a large humidity range. See your CO detectors manual.
- In colder climates, humidity levels can fall well below 50% (in fact the humidity should not be higher than 40%) during the cold season when furnaces and other fuel burning appliances are in full operation.
3. Effect of Other Gases and Vapors
- Other gases such as Carbon Dioxide can also trigger a CO alarm. The UL 2034 Standard requires that CO alarms do not alarm when certain concentrations of other gases and vapors exist in the vicinity of a CO detector. The level for Carbon Dioxide in the old standard was low, which may have contributed to many false alarms with first generation CO detectors.
- CO detectors are designed to protect the average healthy human from death or serious injury under the current standards; however –
- People who are more susceptible cannot depend on these devices for total protection. In this case, more sensitive CO detecting equipment should be used.
- Several groups are working with UL to improve the standards. October 1999 revisions have already been drafted.
- There is room for improvement by imposing stricter standards as well as technological development.
- It is critical that people understand the dangers of CO and that the people who investigate it are properly trained and are using CO testing equipment properly.
Where to install a CO detector?
- One or more CO detectors in accordance with the manufacturer’s recommendations. Usually one per floor.
- Maintain and test regularly as instructed by the manufacturer.
Things to look for when buying a CO detector?
- Type of sensor (electrochemical)
- Certification-UL 2034
- Conforms to new standard
- IAS 6-96 is a supplementary standard to the UL 2034 which includes reliability testing. This standard may not be visible on the box.
- Other considerations include digital display, sensor life, power source, and warranty.
How does all of this relate to your home inspection?
A home inspection may reveal a potential Carbon Monoxide source.
Common deficiencies found during inspections include:
- Venting deficiencies
- Damaged or rusted flue pipes
- Dirty or blocked chimney flues
- Cracked heat exchangers
- Gas proofing deficiencies
- Inadequate combustion air
- Poorly installed equipment
- Visual Inspection
- Equipment available
There are other ways to test CO levels in a home. These tests go beyond the scope of a standard home inspection.
Ground fault circuit interrupters (GFCI’s) are outlets with the colored "Test" and "Reset" buttons specially designed to better protect people than ordinary outlets. GFCI's have been used in houses since the 1970's.
Why Are They Used?
GFCI's are designed to shut power off if there is a very small leak of electricity (a ground fault) which ordinary outlets wouldn't notice. Normal outlets are shut off by a fuse or breaker if more than 15 amps flow. This prevents fires, but since people can be killed by 1 amp or less, fuses may not protect people from shock. GFCI's shut off power if a leak as small as .005 amp occurs.
How Do They Work?
A GFCI detects a leak by comparing how much electricity comes back through the white wire to how much was sent in the black wire. When everything is working correctly, the current flow is the same. If a little electricity is leaking out, it may be going through a ground wire or through part of the house. If this happens, the black wire will have more electricity than the white wire. Electricity, like most people, will follow the path of least resistance. If a person touches a leaky electrical system, they may present a better route to ground for electricity, since they may offer very little resistance.
Another way of saying this is that the person may be a very good conductor or the person may not be well insulated. The electricity will flow through the person, giving them a shock. Without a GFCI, this can be fatal. With a GFCI, the little leak would be detected and the power would be shut off.
Where Are They Used?
In Canada, GFCI's are now required by Code for outdoor outlets, bathroom outlets and whirlpool outlets. Electrical systems for swimming pools are also GFCI protected. In the United States, kitchen outlets within six feet of the sink must also be GFCI protected.
Can The Outlet Be GFCI Protected If There Is No Button?
Yes, if for example, the circuit breaker back at the panel has a "Test" button, it is a GFCI breaker. This will protect everything on that particular circuit. Any outlets wired downstream of a GFCI outlet are also protected if the GFCI is wired correctly.
Can They Be Added To Older Houses?
Yes, GFCI's can be added to any electrical system. They are more expensive than regular outlets ($15-$20 vs. $1-$2), but are inexpensive insurance. While they do not replace grounding systems exactly, some Codes do allow GFCI's in lieu of grounding in some cases. It is safe to say that a circuit protected by a GFCI is better protected than one without.
Abs — A type of black plastic pipe commonly used for waste water lines.
Aggregate — Crushed rock or stone.
Air chamber — A vertical, air filled pipe that prevents water hammer by absorbing pressure when water is shut off at a faucet or valve.
Air-conditioner condenser — The outside fan unit of the air conditioning system. The condenser discharges heat to the building exterior.
Alligatoring — Coarse checking pattern on the surface of a material. Typically caused by ageing, exposure to sun and/or loss of volatiles.
Ampacity — Refers to the how much current a wire can safely carry. For example, a 12-gauge electrical copper wire can safely carry up to 20 amps.
Asphalt — A bituminous material employed in roofing and road paving materials because of its waterproofing ability.
Backfill — The replacement of excavated earth into a trench or pit.
Backflow — A reverse flow of water or other liquids into the water supply pipes, caused by negative pressure in the pipes.
Ballast — A transformer that steps up the voltage in a florescent lamp.
Balusters — Vertical members in a railing used between a top rail and bottom rail or the stair treads. Sometimes referred to as pickets or spindles.
Base sheet — Bottom layer of built-up roofing.
Batt — A section of fiberglass or rock-wool insulation.
Bay window — Any window space projecting outward from the walls of a building, either square or polygonal in plan.
Beam — A structural member transversely supporting a load. A structural member carrying building loads (weight) from one support to another. Sometimes called a girder.
Bearing wall — A wall that supports any vertical load in addition to its own weight.
Bird’s-mouth cut — A cutout in a rafter where it crosses the top plate of the wall providing a bearing surface for nailing. Also called a heel cut.
Bitumen — Term commonly applied to various mixtures of naturally occurring solid or liquid hydrocarbons, excluding coal. These substances are described as bituminous. Asphalt is a bitumen. See Asphalt.
Blocking — Small wood pieces to brace framing members or to provide a nailing base for gypsum board or paneling.
Board and batten — A method of siding in which the joints between vertically placed boards or plywood are covered by narrow strips of wood.
Bottom chord — The lower or bottom horizontal member of a truss.
Brick tie — Metal strips or wires that are inserted into the mortar joints of the brick veneer. Ties hold the veneer wall to the backer wall behind it.
Brick veneer — A vertical facing of brick used to clad a building. Brick veneer is not a load-bearing component. Read More on page 116 of Brick Veneer.
Building paper — A general term for papers, felts and similar sheet materials used in buildings without reference to their properties or uses. Generally comes in long rolls.
Built-up roof — A roofing composed of three to five layers of asphalt felt laminated with coal tar, pitch or asphalt. The top is finished with crushed slag or gravel. Generally used on flat or low-pitched roofs.
Butt joint — The junction where the ends of building materials meet. To place materials end-to-end or end-to-edge without overlapping.
Cant strip — A triangular shaped piece of lumber used at the junction of a flat deck and a wall to prevent cracking of the roofing which is applied over it.
Cantilever — Any part of a structure that projects beyond its main support and is balanced on it.
Cap flashing — The flashing covering over a horizontal surface to prevent water from migrating behind the base flashing.
Cap sheet — The top layer in modified bitumen roofing.
Casement window — A window with hinges on one of the vertical sides and swings open like a door.
Ceiling joist — One of a series of parallel framing members used to support ceiling loads and supported in turn by larger beams, girders or bearing walls. Can also be roof joists.
Cement — The grey powder that is the “glue” in concrete. Portland cement. Also, any adhesive.
Certificate of Occupancy — Certificate is issued by the local municipality and is required before anyone can occupy and live within the building. It is issued only after the local municipality has made all inspections and all monies and fees have been paid.
Cfm (cubic feet per minute) — A rating that expresses the amount of air a blower or fan can move. The volume of air (measured in cubic feet) that can pass through an opening in one minute.
Chase — A framed enclosed space around a flue pipe or a channel in a wall, or through a ceiling for something to lie in or pass through.
Checking — Cracks that appear with age in many large timber members. The cracks run parallel to the grain of the wood. At first superficial, but in time may penetrate entirely through the member and compromise its integrity.
Cleanout — An opening providing access to a drain line. Closed with a threaded plug.
Closed-cut valley — A method of valley treatment in which shingles from one side of the valley extend across the valley, while shingles from the other side are trimmed 2 inches from the valley centerline. The valley flashing is not exposed.
Collar tie — Nominal one- or two-inch-thick members connecting opposite roof rafters. They serve to stiffen the roof structure.
Column — A vertical structural compression member that supports loads acting in the direction of its longitudinal axis.
Combustion air and ventilation air — The ductwork installed to bring fresh, outside air to the furnace or boiler room. Normally two separate supplies of air are brought in: one high for ventilation and one low for combustion.
Compressor — A mechanical device that pressurizes a gas in order to turn it into a liquid, thereby allowing heat to be removed or added. A compressor is the main component of conventional heat pumps and air conditioners. In an air conditioning system, the compressor normally sits outside and has a large fan (to remove heat).
Concrete board or cement board — A panel made out of concrete and fiberglass, usually used as a tile backing material.
Condensate drain line — The pipe that runs from the air conditioning cooling coil to the exterior or internal building drain, to drain away condensation.
Condensation — The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.
Condensing unit — The outdoor component of a cooling system. It includes a compressor and condensing coil designed to give off heat.
Conduit, electrical — A pipe, usually metal, in which wire is installed. The pipe serves to protect the wire.
Control joint — Tooled, straight grooves made on concrete floors or structures to “control” where the concrete should crack (as a result of shrinkage).
Cooling load — The amount of cooling required to keep a building at a specified temperature during the summer, usually 25° C, based on a design outside temperature.
Corbel — To build out one or more courses of brick or stone from the face of a wall. This may be decorative, or serve to support a structural component.
Counterflashing — A metal flashing usually used to cover another flashing and prevent moisture entry.
Course — A row of shingles or roll roofing running the length of the roof. Parallel layers of building materials such as bricks, or siding laid up horizontally.
Cpvc — See pvc.
Crawlspace — A shallow space below a building, normally enclosed by the foundation walls.
Cricket — A saddle-shaped, peaked construction connecting a sloping roof plane with a wall or chimney. Designed to encourage water drainage away from the chimney or wall joint.
Culvert — Round, corrugated drain pipe (normally 15 or 18 inches in diameter) installed beneath a driveway and parallel to and near the street.
Cupping — A type of warping that causes boards or shingles to curl up at their edges. Typically caused by uneven drying or loss of volatiles.
Curb — The short elevation of a supporting element above the deck of a roof. Normally a box (on the roof) on which a skylight or piece of mechanical equipment is attached.
Curtain wall — An exterior building wall that is supported entirely by the building structure, rather than being self-supporting or load-bearing.
Damper — A metal “door” placed within the ductwork, typically. Used to control flow of air, etc., in the ductwork.
Damp-proofing — The black, tar-like material applied to the exterior of a foundation wall. Used to minimize moisture penetration into the wall.
Deck — The surface, installed over the supporting framing members, to which the roofing is applied.
Dedicated circuit — An electrical circuit that serves only one appliance or a series of electric heaters or smoke detectors.
Dew point — Temperature at which a vapor begins to deposit as a liquid. Applies especially to water in the atmosphere.
Disconnect — A large electrical on-off switch.
Diverter valve — A device that changes the direction of water flow from one faucet to another.
Dormer — A box-like projection from the sloping plane of a roof that frames a window.
Double-hung window — A window with two vertically sliding sashes, both of which can move up and down.
Downspout — A pipe for draining water from roof gutters. Also called a leader.
Drain tile — A perforated, corrugated plastic pipe laid at the bottom of the foundation wall and used to drain excess water away from the foundation. It prevents ground water from seeping through the foundation wall. Sometimes called perimeter drain.
Drip — A groove in the underside of a sill or drip cap to cause water to drop off on the outer edge instead of drawing back and running down the face of the building.
Ducts — Usually round or rectangular metal pipes installed for distributing warm or cold air from the heating and air-conditioning equipment.
Eaves protection — Additional layer of roofing material applied at the eaves to help prevent damage from water backup (typically caused by ice damming).
Eifs — Exterior Insulation Finish System. An exterior cladding system that employs a relatively thin acrylic stucco coating over insulation panels. (Pronounced “ee-fus”) Read more on page 50 of Exterior Insulation Finish System (EIFS).
Elbow — A plumbing or electrical fitting that lets you change directions in runs of pipe or conduit.
Evaporator coil — The part of a cooling system that absorbs heat from air passing through it. The evaporator coil is found within the ductwork.
Expansion joint — A joint that allows for building material expansion and contraction caused by temperature changes.
Exposed aggregate finish — A method of finishing concrete which washes the cement/sand mixture off the top layer of the aggregate — usually gravel. Often used with precast concrete exterior wall finishes.
Exposure — The portion of the roofing or wall cladding material exposed to the weather after installation.
Fascia — a vertical member attached to the ends of the roof structure and often the backing of the gutter.
Felt — Fibrous material saturated with asphalt and used as an underlayment or part of a built-up roofing system.
Finger joint — A manufacturing process of interlocking two shorter pieces of wood end to end to create a longer piece of dimensional lumber or molding. Often used in jambs and casings and are normally painted (instead of stained).
Fire stop — A solid, tight closure of a concealed space, placed to prevent the spread of fire and smoke through such a space. Includes stuffing wire and pipe holes in the fire separations.
Flashing — (1) Sheet metal or flexible membrane pieces fitted to the joint of any roof intersection, penetration or projection (chimneys, copings, dormers, valleys, vent pipes, etc.) to prevent water leakage. (2) The building component used to connect portions of a roof, deck, or siding material to another surface such as a chimney, wall, or vent pipe. Often made out of various metals, rubber or tar and is mostly intended to prevent water entry.
Flatwork — Common word for concrete floors, driveways, patios and sidewalks.
Flue — The space or passage in a chimney through which smoke, gas, or fumes ascend.
Fluorescent lighting — A fluorescent lamp is a gas-filled glass tube with a phosphor coating on the inside. Gas inside the tube is ionized by electricity which causes the phosphor coating to glow. Normally with two pins that extend from each end.
Footing — A widened, below-ground base of a foundation wall or a poured concrete, below-ground, base used to support foundations or piers.
Forced air heating — a common form of heating with natural gas, propane, oil or electricity as a fuel. Air is heated through a heat exchanger and distributed through a set of metal ducts.
Form — Temporary structure erected to contain concrete during placing and initial hardening.
Foundation — The supporting portion of a structure below the first floor construction, or below grade, including the footings.
Framing — The structural wood, steel or concrete elements of the building.
Framing, balloon — A system of framing a building in which all vertical structural elements of the bearing walls consist of single pieces extending from the top of the foundation sill plate to the roof plate and to which all floor joists are fastened.
Frost line — The depth of frost penetration in soil and/or the depth at which the earth will freeze and swell. This depth varies in different parts of the country.
Furring — Strips of wood or metal applied to a wall or other surface to even it and normally to serve as a fastening base for finish material.
Gable — A sidewall, typically triangular, that is formed by two sloping roof planes.
Gable roof — A type of roof with sloping planes of the same pitch on each side of the ridge. Has a gable at each end.
Gasket — A device used to seal joints against leaks.
GFI or GFCI or Ground Fault Current Interrupter — A electrical device used to prevent injury in locations where one might be in contact with a grounded surface and an electrical appliance. Most gfis are located in a receptacle or circuit breaker and can be identified by the presence of a “test” and a “reset” button. Read more on page 165 of Ground Fault Circuit Interrupters (GFCI).
Glued laminated beam (glulam) — A structural beam composed of wood laminations. The laminations are pressure-bonded with adhesives.
Granules — Crushed rock coated with ceramic material, applied to the exposed surface of asphalt roofing products to add color and reduce ultraviolet degradation. Copper compounds added to these help make them algae resistant.
Groundwater — Water from a subsurface water source.
Grout — Mortar made of such consistency (by adding water) that it will flow into the joints and cavities of the masonry work and fill them solid.
Gusset — A flat metal, wood, plywood or similar type member used to provide a connection at the intersection of wood members. Most commonly used at joints of wood trusses. They are fastened by nails, screws, bolts, or adhesives.
Gutter — The trough that channels water from the eaves to the downspouts.
H-beam — A steel beam with a cross section resembling the letter H.
H-clip — Small metal clips formed like an H that fits at the joints of two plywood (or wafer board) sheets to stiffen the joint. Normally used on the roof sheeting.
Header — A beam placed perpendicular to joists and to which joists are attached in framing for around an opening.
Hearth — The fireproof area directly in front of a fireplace. The inner or outer floor of a fireplace, usually made of brick, tile, or stone.
Heat pump — A device that uses compression and decompression of gas to heat and/or cool a building.
Heating load — The amount of heating required to keep a building at a specified temperature during the winter, based on an outside design temperature.
Hip — The external angle formed by the meeting of two sloping sides of a roof.
Honeycombs — The appearance concrete makes when aggregate in the concrete is visible and where there are void areas in the concrete.
Hose bib — An exterior water faucet.
Hot wire — The wire that carries electrical energy to a receptacle or other device - in contrast to a neutral, which carries electricity away again. Normally the black wire.
Hvac — An abbreviation for Heat, Ventilation, and Air Conditioning.
I-beam — A steel beam with a cross section resembling the letter I.
Ice damming — The buildup of ice and water at the eaves of a sloped roof. Melting snow on the roof refreezes at the roof overhang, causing the damming. Buildings with inadequate attic insulation or ventilation or with large roof projections beyond the exterior walls are more prone to ice damming.
Irrigation — Lawn sprinkler system.
Jack post — A type of structural support made of metal, which can be raised or lowered through a series of pins and a screw to meet the height required. Typically used as a replacement for an old supporting member in a building.
Joist — One of a series of parallel beams, usually two inches in thickness, used to support floor and ceiling loads, and supported in turn by larger beams, girders, or bearing walls.
Joist hanger — A metal U-shaped item used to support the end of a floor joist and attached with hardened nails to another bearing joist or beam.
Knob-and-tube wiring — A common form of electrical wiring used before the Second World War. When in good condition it may still be functional for low amperage use such as smaller light fixtures. Read more on page 171 of Knob and Tube Wiring
Lath — A building material of narrow wood, metal, gypsum, or insulating board that is fastened to the frame of a building to act as a base for plaster, shingles, or tiles.
Lattice — An open framework of crisscrossed wood or metal strips that form regular, patterned spaces.
Leader — See Downspout.
Ledger — The wood or metal members attached to a beam, studding, or wall used to support joist or rafter ends.
Lintel — A horizontal structural member that supports the load over an opening such as a door or window.
Load-bearing wall — A wall supporting its own weight and some other structural elements of the building such as the roof and floor structures.
Louvre — A vented opening into a room that has a series of horizontal slats and arranged to permit ventilation but to exclude rain, snow, light, insects, or other living creatures.
Mansard roof — A roof with two sloping planes of different pitch on each of its four sides. The lower plane is steeper than the upper, and may be almost vertical.
Masonry — Stone, brick, concrete, hollow-tile, concrete block, or other similar building units or materials. Normally bonded together with mortar to form a wall.
Modified bitumen roof — A roof covering that is typically composed of a factory-fabricated composite sheet consisting of a copolymer-modified bitumen, often reinforced with polyester and/or fiberglass, and installed in one or more plies. The membrane is commonly surfaced with field-applied coatings, factory-applied granules or metal foil. The roofing system may incorporate rigid insulation.
Mortise — A slot cut into a board, plank, or timber, usually edgewise, to receive the tenon (or tongue) of another board, plank, or timber to form a joint.
Mullion — A vertical divider in the frame between windows, doors, or other openings.
P-trap — Curved, U-section of drain pipe that holds a water seal to prevent sewer gasses from entering a building through a fixtures’ drain pipe.
Parapet — The portion of an exterior wall that extends above the edge of a roof.
Parging — A thin layer of cement placed over masonry units.
Partition — A wall that subdivides spaces within any story of a building or room.
Paver — Materials (commonly masonry) laid down to make a firm, even surface on the exterior.
Performance bond — An amount of money (usually 10 percent of the total price of a job) that a contractor must put on deposit with a governmental agency as an insurance policy that guarantees the contractors’ proper and timely completion of a project or job.
Perimeter drain — Typically 4-inch perforated plastic pipe around the perimeter (either inside or outside) of a foundation wall (before backfill) that collects and diverts ground water away from the foundation.
Pilot light — A small, continuous flame (in a boiler, or furnace) that ignites gas or oil burners when needed.
Pitch — (1) The degree of roof incline expressed as the ratio of the rise, in feet, to the span, in feet. (2) A thick, oily substance commonly obtained from tar, used to seal out water at joints and seams. Pitch is produced from distilling coal tar, wood tar, or petroleum.
Pitch pocket — A container, usually formed of sheet metal, around supporting connections with roof-mounted equipment. Filling the container with pitch, or better yet, plastic roof cement, helps seal out water even when vibration is present. A pitch pocket is not the preferred method of flashing a roof penetration.
Plan view — Drawing of a structure with the view from overhead, looking down.
Plate — Normally a horizontal member within a framed structure, such as: (1) sill plate — a horizontal member anchored to a concrete or masonry wall; (2) Sole plate — bottom horizontal member of a frame wall; or (3) top plate — top horizontal member of a frame wall supporting ceiling joists, rafters, or other members.
Plenum — The main supply air or return air duct leading from a heating or cooling unit.
Plumbing stack — A plumbing vent pipe that penetrates the roof.
Ply — A term to denote the number of layers of roofing felt, veneer in plywood, or layers in built-up materials, in any finished piece of such material.
Point load — A point where a bearing/structural weight is concentrated and transferred to another structural member or component.
Portland cement — Cement made by heating clay and crushed limestone into a brick and then grinding to a pulverized powder state.
Post — a vertical framing member usually designed to carry a beam.
Post-and-beam — A basic building method that uses just a few hefty posts and beams to support an entire structure. Contrasts with stud framing.
Power vent — A vent that includes a fan to speed up air flow.
Pressure relief valve — A safety device mounted on a water heater or boiler. The relief valve is designed to release any high pressure in the vessel and thus prevent tank explosions.
Pressure-treated wood — Lumber that has been saturated with a preservative to resist rot.
Pvc or cpvc — (Polyvinyl choride) A type of white or light gray plastic pipe sometimes used for water supply lines and waste pipe.
Quarry tile — A man-made or machine-made clay tile used to finish a floor or wall. Generally 6-inches by 6-inches by ¼-inch thick.
R value — A measure of insulation’s resistance to heat flow. The higher the R value the more effective the insulation.
Rafter — (1) The framing member that directly supports the roof sheathing. A rafter usually follows the angle of the roof, and may be a part of a roof truss. (2) The supporting framing member immediately beneath the deck, sloping from the ridge to the wall plate.
Rafter, hip — A rafter that forms the intersection of an external roof angle.
Rafter, valley — A rafter that forms the intersection of an internal roof angle.
Rake edge — The overhang of an inclined roof plane beyond the vertical wall below it.
Rebar — Reinforcing bar. Ribbed steel bars installed in concrete structures designed to strengthen concrete. Comes in various thicknesses and strength grades. May be epoxy coated to enhance rust resistance.
Refrigerant — A substance that remains a gas at low temperatures and pressure and can be used to transfer heat. Freon is an example.
Register — A grille placed over a supply air or return air duct.
Reglaze — To replace a broken window.
Reinforcing — Steel rods or metal fabric placed in concrete slabs, beams, or columns to increase their strength.
Relief valve — A device designed to open if it detects excess temperature or pressure. Commonly found on water heating or steam producing systems.
Resilient flooring — A durable floor cover that has the ability to resume its original shape.
Retaining wall — A structure that holds back a slope or elevation of land and prevents erosion.
Ridge — The horizontal line at the junction of the top edges of two sloping roof surfaces.
Riser — A vertical member between two stair treads.
Roll roofing — Asphalt roofing products manufactured in roll form.
Romex — A name brand of nonmetallic sheathed electrical cable that is used for indoor wiring.
Roof deck — The surface, installed over the supporting framing members, to which the roofing is applied.
Roof sheathing — The wood panels or sheet material fastened to the roof rafters or trusses on which the shingle or other roof covering is laid.
Roof valley — The “V” created where two sloping roofs meet.
Roofing membrane — The layer or layers of waterproofing products that cover the roof deck.
Run, stair — The horizontal distance of a stair tread from the nosing to the riser.
Saddle — Two sloping surfaces meeting in a horizontal ridge, used between the back side of a chimney, or other vertical surface, and a sloping roof. Used to divert water around the chimney or vertical surface.
Sanitary sewer — A sewer system designed for the collection of waste water from the bathroom, kitchen and laundry drains, and is usually not designed to handle storm water.
Sash — The frame that holds the glass in a window, often the movable part of the window.
Saturated felt — A felt that is impregnated with tar or asphalt.
Scratch coat — The first coat of plaster, which is scratched to form a bond for a second coat.
Scupper — (1) An opening for drainage in a wall, curb or parapet. (2) The drain above a downspout or in a flat roof, usually connected to the downspout.
Sealer — A finishing material, either clear or pigmented, that is usually applied directly over raw wood or concrete for the purpose of sealing the wood or concrete surface.
Seasoning — Drying and removing moisture from green wood in order to improve its usability.
Service equipment — Main control gear at the electrical service entrance, such as circuit breakers, switches, and fuses.
Service lateral — Underground power supply line.
Shake — A wood roofing material, normally cedar or redwood. Produced by splitting a block of the wood along the grain line. Modern shakes are sometimes machine sawn on one side.
Sheathing — (1) Sheets or panels used as roof deck material. (2) Panels that lie between the studs and the siding of a structure.
Short circuit — A situation that occurs when hot and neutral wires come in contact with each other. Fuses and circuit breakers protect against fire that could result from a short.
Sill — (1) The two-by-four or two-by-six wood plate framing member that lays flat against and bolted to the foundation wall (with anchor bolts) and upon which the floor joists are installed. (2) The member forming the lower side of an opening, as a door sill or window sill.
Skylight — A more or less horizontal window located on the roof of a building.
Slab-on-grade — A type of foundation with a concrete floor which is placed directly on the soil. In warm climates, the edge of the slab is usually thicker and acts as the footing for the walls. In cold climates, the slab is independent of the perimeter foundation walls.
Sleeper — Usually, a wood member that serves to support equipment.
Soffit — (1)The finished underside of the eaves. (2) A small ceiling-like space, often out of doors, such as the underside of a roof overhang.
Solid waste pump — A pump used to ‘lift’ waste water to a gravity sanitary sewer line. Usually used in basements and other locations which are situated below the level of the city sewer.
Spalling — The cracking and breaking away of the surface of a material.
Span — The clear distance that a framing member carries a load without support (between structural supports).
Splash block — A pad placed under the lower end of a downspout to divert the water from the downspout away from the building. Usually made out of concrete or fiberglass.
Stair stringer — Supporting member for stair treads. Can be a notched plank or a steel member.
Starter strip — Asphalt roofing applied at the eaves that provides protection by filling in the spaces under the cutouts and joints of the first course of shingles.
Step flashing — Flashing application method used where a vertical surface meets a sloping roof plane.
Storey — That part of a building between any floor or between the floor and roof.
Storm collar — A metal flashing used to seal around a penetration in a roof.
Storm sewer — A sewer system designed to collect storm water, separate from the waste water system.
Storm window — An extra window usually placed outside of an existing one, as additional protection against cold weather, or damage.
Stucco — An outside plaster finish made with Portland cement as its base.
Stud — One of a series of slender wood or metal vertical structural members placed as supporting elements in walls and partitions.
Stud framing — A building method that distributes structural loads to each of a series of relatively lightweight studs. Contrasts with post-and-beam.
Sump — Pit or large plastic bucket/barrel inside a basement, designed to collect ground water (storm water) from a perimeter drain system.
Sump pump — A submersible pump in a sump pit that pumps any excess ground water to the storm sewer.
Suspended ceiling — A ceiling system supported by hanging it from the overhead structural framing.
Tempered — Strengthened. Tempered glass will not shatter nor create shards, but will “pelletize” like an automobile window. Required in tub and shower enclosures, for example.
Termites — Insects that superficially resemble ants in size, general appearance, and habit of living in colonies; hence, they are frequently called “white ants.” Subterranean termites establish themselves in buildings not by being carried in with lumber, but by entering from ground nests after the building has been constructed. If unmolested, they eat out the woodwork, leaving a shell of sound wood to conceal their activities, and damage may proceed so far as to cause collapse of parts of a structure before discovery.
Terra cotta — A ceramic material molded into masonry units.
Threshold — The bottom metal, concrete, or wood plate of an exterior door frame. They may be adjustable to keep a tight fit with the door slab.
Toenailing — To drive a nail in at a slant. Method used to secure floor joists to the plate. Not acceptable for securing joists flush to a header or beam.
Tongue-and-groove — A joint made by a tongue (a rib on one edge of a board) that fits into a corresponding groove in the edge of another board to make a tight flush joint. Typically, the subfloor plywood is tongue-and-groove.
Top chord — The upper or top member of a truss.
Trap — A plumbing fitting that holds water to prevent air, gas, and vermin from entering into a building.
Tread — The walking surface board in a stairway on which the foot is placed.
Treated lumber — A wood product which has been impregnated with chemicals to reduce damage from wood rot or insects. Often used for the portions of a structure which is likely to be in ongoing contact with soil and water. Wood may also be treated with a fire retardant.
Truss — An engineered and manufactured roof support member with “zig-zag” framing members. Does the same job as a rafter but is designed to have a longer span than a rafter. Read more on page 129 of truss' s.
Tube-and-knob wiring — See page 171 of knob-and-tube wiring.
Uffi — Urea Formaldehyde Foam Insulation, a foam insulation blown into existing walls. (Pronounced “you-fee”) Read more on page 270 of Urea Formaldehyde Foam Insulation (UFFI).
Ultraviolet degradation — A reduction in certain performance limits caused by exposure to ultraviolet light.
Underlayment — (1) A one-quarter-inch material placed over the subfloor plywood sheathing and under finish coverings, such as vinyl flooring, to provide a smooth, even surface. (2) A secondary roofing layer that is waterproof or water-resistant, installed on the roof deck and beneath shingles or other roof-finishing layer.
UV rays — Ultraviolet rays from the sun.
Valley — The inward angle formed by two intersecting, sloping roof planes. Since it naturally becomes a water channel, additional attention to waterproofing it is desirable.
Vapor barrier — A building product installed on exterior walls and ceilings under the drywall and on the warm side of the insulation. It is used to retard the movement of water vapor into walls and prevent condensation within them. Normally, polyethylene plastic sheeting is used.
Vent — A pipe or duct allowing the flow of air and gases to the outside. In a plumbing system, the vent is necessary to allow sewer gases to escape to the exterior.
Vermiculite — A mineral closely related to mica, with the faculty of expanding on heating to form lightweight material with insulation quality. Used as bulk insulation and also as aggregate in insulating and acoustical plaster and in insulating concrete floors.
Water closet — A toilet.
Weather stripping — Narrow sections of thin metal or other material installed to prevent the infiltration of air and moisture around windows and doors.
Weep holes — Small holes in exterior wall cladding systems that allow moisture to escape and air pressure equalization in the cavity space drained by the weep hole.
Wythe — (rhymes with “tithe” or “scythe”) A vertical layer of masonry that is one masonry unit thick.
Zone — The section of a building that is served by one heating or cooling loop because it has noticeably distinct heating or cooling needs. Also, the section of property that will be watered from a lawn sprinkler system.
Zone valve — A device, usually placed near the heater or cooler, which controls the flow of water or steam to parts of the building; it is controlled by a zone thermostat.
There are so many home maintenance and repair items that are important; it can be confusing trying to establish which are the most critical. To simplify things, we have compiled a short list of our favorites. These are by no means all-inclusive, nor do they replace any of the information in a home inspection report. They should, however, help you get started on the right foot. Remember, any items marked as priority or safety issues on your home inspection report need immediate attention.
- Install smoke detectors and carbon monoxide detectors as required, according to manufacturer’s recommendations. Know the requirements in your area.
- Make any electrical improvements recommended in the home inspection report.
- Remove any wood/soil contact to prevent rot and insect damage.
- Change the locks on all doors. Use a dead bolt for better security and to minimize insurance costs.
- Correct trip hazards such as broken or uneven walks and driveways, loose or torn carpet or uneven flooring.
- Correct unsafe stairways and landings. (Railings missing, loose, too low, et cetera.)
- Have all chimneys inspected before operating any of these appliances.
- Locate and mark the shut-offs for the heating, electrical and plumbing systems.
- Label the circuits in electrical panels.
- If there is a septic system, have the tank pumped and inspected. If the house is on a private water supply (well), set up a regular testing procedure for checking water quality.
Regular Maintenance Items
- Clean the gutters in the spring and fall.
- Check for damaged roofing and flashing materials twice a year.
- Cut back trees and shrubs from the house walls, roof and air conditioning system as needed.
- Clean the tracks on horizontal sliding windows annually, and ensure the drain holes are clear.
- Test ground fault circuit interrupters, carbon monoxide detectors and smoke detectors using the test button, monthly.
- Service furnace or boiler yearly.
- Check furnace filters, humidifiers and electronic air cleaners monthly.
- Check the bathtub and shower caulking monthly and improve promptly as needed.
- If you are in a climate where freezing occurs, shut off outdoor water faucets in the fall.
- Check reversing mechanism on garage door opener monthly.
- Check attics for evidence of leaks and condensation and make sure vents are not obstructed, at least twice a year. (Provide access into all attics and crawl spaces.)
"This house isn't going anywhere." Or is it!?
Serious structural problems in houses are not very common, but when they occur they are never cheap to fix. Some can’t be fixed at all. This report won’t turn you into a home inspector, but it will give you some of the common indicators.
Uneven floors are typical, particularly in older homes. Here is a trick to help distinguish between a typical home with character and a structural problem. It’s not unusual for an older home to have the floor sag in the middle. On the other hand, if the floor slopes toward an outside wall, there is a good chance that the house has a significant structural problem.
While no house is perfect, this is one area where you should be very careful. Take a look at the house from across the street. If the house appears to be leaning one way or the other, there may be a structural problem. It may help to line up a front corner of the house with the back corner of an adjacent house just for reference. The corners should be parallel. Stepping back from the house to take a look is always a good idea. It is easy to miss something major by standing too close to it! If there is a lean that is detectable by eye, don’t take any chances. Get it checked out.
Horizontal Foundation Cracks are Bad
It is not uncommon to find cracks in the foundation. This goes for new houses as well as old ones. While there is a great deal of engineering that goes into “reading” these cracks, there is one rule that you should never forget. “Horizontal cracks are a problem”. Of course not all vertical cracks are acceptable, but they are generally not as serious as a horizontal crack.
Shrinkage cracks in a new house: Most new foundations will develop small vertical cracks. These cracks are a result of the concrete shrinking as it cures. These cracks are about 1 /8 inch wide or less. They don’t affect the structure. The only concern is leakage. If you see small cracks in a new foundation, don’t panic. In fact, in a new home, some builders will pre-crack the foundation and fill the crack with flexible material.
Few things are more misunderstood than plaster cracks on the inside of the house.
The following crack types are not generally related to structural movement -
- a small crack (less than 1/4 inch) that follows the corner of the room where two walls meet
- small cracks that extend up from the upper corner of a door opening
The following cracks may be related to structural movement –
- large cracks (larger than 1/4 inch in width)
- cracks that run diagonally across the wall
- cracks on the interior finish that are in the same vicinity as cracks on the exterior of the house.
Truss uplift is a phenomenon common in homes built with roof trusses as opposed to rafters.
If a house suffers from truss uplift, the top floor ceilings literally lift off the interior walls in the winter. They drop back down in the summer. Needless to say, this is a tad disconcerting to the homeowner. At first glance, one might assume that the floors have settled. Actually the ceiling has gone up - sometimes creating a gap of as much as two inches where interior walls meet the ceilings.
What is a Truss?
Trusses are prefabricated structural assemblies which hold up the roof and the top floor ceilings. Trusses tend to be a stronger, lighter and less expensive approach to roof framing. Trusses are strong because they make use of the most efficient geometric shape we know of - the triangle. Trusses are a series of triangles fastened together with gusset plates. The outside members of a truss are called chords while the inner pieces are known as webs.
Why Truss Uplift?
Houses have changed over the years. Attics of newer houses have lots of insulation and ventilation. They also have roof trusses instead of rafters and ceiling joists. The bottom chord of a truss is buried below a deep blanket of insulation. Even on the coldest days the bottom chord is nice and warm. The top chords however, are above the insulation and get very cold in a well ventilated attic.
While the bottom chord is warm and is drying out, the top chords are doing just the opposite. The cold winter air has very high relative humidity. The top chords absorb moisture from the air causing them to elongate. With the top chords growing and the bottom chord shrinking, the truss arches up in the middle causing the ceilings to lift off the walls. In the summer, the cycle reverses itself.
What Is The Problem?
No problem really - from a structural point of view. But cosmetically it's another story. No one has yet solved the problem, but some builders mask it by securing the ceiling drywall to the top of the walls and not to the trusses for a distance of 18 inches away from the walls. The drywall flexes and stays fastened to the walls while the trusses lift above it.
Others use a decorative molding where the walls meet the ceilings. They fasten the moldings to the ceilings but not to the walls. As the ceilings move up, the moldings go with them hiding the gap.
One little tip to remember. If you're redecorating, always do it in the winter when the ceiling is at its highest point. Otherwise you'll have a stripe around the room below the molding next winter!
Let's start by differentiating between a home improvement and a home repair. A home improvement, as the name implies, means improving something. It is usually a renovation to create more space, changing the layout of the house, improving energy efficiency, or to making aesthetic changes.
This report will deal with the simpler topic of home repair – basically replacing things that are worn out or fixing things that are broken. Here are some very basic rules to follow.
1. Know what you want done
If you are replacing a worn out furnace, for example, do some research to find out whether you want a mid-efficiency furnace or a high-efficiency furnace. If you are repairing a roof with a leaking valley flashing, determine whether you want the valley flashing replaced or just patched to last a few years until the whole roof needs re-flashing.
If you know what you want done, you can compare apples to apples when reviewing quotations. Otherwise it would be very hard to compare various quotes if every contractor has a different repair strategy.
Be prepared to stick to your guns. Many contractors will tell you that the job is much bigger, much harder, or it must be done his way (because if you don't, it will be “dangerous”, or much more expensive the next time.)
As home inspectors, we are often faced with contractor opinions that differ drastically from the recommendations in our reports. In many of these cases, the contractor is proposing unnecessary work.
2. Find at least 3 experienced, reputable contractors who are capable of doing the work
This may sound easier than it is. While it is best to rely on personal referrals from people you trust, these referrals must be taken with a grain of salt. Former customers of contractors are not usually in a position to comment on the quality of the installation of a furnace, for example.
Also be sure the type of work that you are planning to have done is similar (in size and scope) to the work done for the person providing the referral. Many contractors who are geared to do major renovations are not well suited to do minor repairs and vice versa.
3. Obtain 3 written estimates
Our experience has shown that contractor quotes can vary as much as 300% on any given job. This is sometimes due to different perceptions of what needs to be done. This can be avoided by following Step 1 carefully. However, sometimes the variance is simply the result of how busy the contractor is.
4. Get three references from each contractor
Better than three references is a list of the recent clients that the contractor has worked for. That way you get to choose who you would like to select as a reference. Follow up with these references bearing in mind the comments in Step 2.
While you are at it, ensure that the contractor has appropriate licenses and insurance.
5. Choose the contractor
Don't necessarily base your choice on price alone. Look carefully at what has been included in the estimates. Select the contractor with the best reputation, provided that the price for the job is fair. Avoid paying cash. The benefit of a cash deal is typically far greater for the contractor than it is for the homeowner.
6. Have both parties sign a contract
The contract should include a complete description of the work. It should also include details as to who is responsible for obtaining permits (if there is any doubt regarding the necessity of a permit, contact your local building department).
The contract should have a start date and a completion date. (On larger contracts, sometimes a penalty clause is included for each day the job extends beyond the completion date.)
The contract must also contain a payment schedule. The schedule should not demand very much money up front and the payment should be based on stages of completion as opposed to pre-determined dates.
Remember to hold back 10% of each payment for 45 days after the completion of the job to determine whether any liens have been placed on the property (as a result of the contractor not paying his sub-contractors).
Also, don't expect much in the way of a guarantee if you are simply asking a contractor to undertake band-aid repairs. Many contractors will not simply patch a damaged valley flashing, for example, even if they are 95% sure that the repair will work. This is because there is still a 5% chance that they will get complaints to fix a subsequent leak. In fairness, the leakage is not their fault. They just do not want the hassles. Consequently, many contractors will suggest repairs which are unnecessary (replacing the entire side of the roof, for example) to reduce the potential for complaints.
A significantly lower price can be obtained if you explain to the contractor that you expect him to do his best, but you aren't going to make him responsible for the future of the entire roof based on a $300 repair.
7. Expect delays
Any type of home repair seems to take longer than was first predicted. If the repairs involve any sort of interior demolition, expect dust.
8. Have a contingency fund
Many home repairs end up unearthing something else that requires repair. While this is very common, ask lots of questions if your contractor is proposing additional work.
We trust that the above information will help people in their dealings with contractors, realign expectations, and perhaps avoid pitfalls.
What Is It?
If you have never seen vermiculite insulation in an attic, you may have seen it in potting soil. Vermiculite is a naturally occurring mineral worldwide. When heated rapidly to high temperatures, this crystalline mineral expands into low density, accordion-like, golden brown strands.
In fact, its worm-like shape is what gives vermiculite its name. The worms are broken into rectangular chunks about the size of the eraser on the end of a pencil. In addition to being light, vermiculite chunks are also absorbent and fire retardant. These characteristics make it great as an additive, for example to potting soil. It also makes a good insulating material.
Where Was It Used?
Sold under various brand names, such as Zonolite Attic Insulation, the insulation came in big bags. Thousands of homeowners simply opened the bags and poured the vermiculite onto their attic floor and sometimes down exterior walls. It was generally not used in new construction.
When Was It Used?
Worldwide, vermiculite has been used in various industries as long ago as 1920. With the upsurge in home ownership during the baby boom, vermiculite insulation was a popular material in the 1950’s, and continued with the energy crisis into the late 1970’s. In Canada, it was one of the insulating materials allowed under the Canadian Home Insulation Program from about 1976 to the mid-1980’s. The CHIP program provided grants to homeowners to increase insulation levels, reducing energy consumption.
What Is The Problem?
The majority of the vermiculite used worldwide was from a mine in Libby, Montana, owned and operated since 1963 by W.R. Grace. The mine was closed in 1990. As well as being rich in vermiculite, this mine had the misfortune of having a deposit of tremolite, a type of asbestos. When the vermiculite was extracted, some tremolite came in with the mix.
For Canadian use, the raw product from the Libby mine was shipped to Grace subsidiary F. Hyde processing plants in Montreal, St. Thomas, Ajax and Toronto, and Grant Industries in western Canada. At these plants, it was processed and sold as Zonolite.
What Is The Risk?
Asbestos minerals tend to separate into microscopic particles that become airborne and are easily inhaled. People exposed to asbestos in the workplace have developed several types of life-threatening diseases, including lung cancer. Workers in and around the Libby mine developed serious health problems.
Like any hazards, length and intensity of exposure are major factors in the risk of asbestos-related respiratory illness. To assess the risk of asbestos exposure at a house, a sample of the vermiculite would need to be analyzed by a lab. Since most of the vermiculite used in Canada was taken from the Libby mine, the odds are quite good that there is asbestos in the vermiculite in Canadian attics.
The good news is that we don’t live in our attics. In addition, as long as it is undisturbed, neither the asbestos fibers bound up in the vermiculite chunks nor the dust will be released into the air. According to the National Institute for Occupational Safety and Health in the U.S., “Most people who get asbestos-related diseases have been exposed to high levels of asbestos for a long time.” Lastly, most of the time the air in your house flows from the house into the attic, rather than into the house from the attic.
The bottom line is, like most household products that may contain asbestos, and there are many, doing nothing is often the best approach. Naturally, the risk of exposure increases with the amount of time spent in the attic.
If the attic or walls of a house contain vermiculite insulation, leave it alone. Avoid disturbing the material. Do not sweep it or vacuum it up. Do not store belongings in the attic.
If work is planned that involves these areas, for example installing recessed lights in a room below the attic, send a sample of the vermiculite to a private lab. Send several samples, and use a lab specializing in asbestos analysis. If it is found to contain asbestos, or if you just assume it does, precautions should be taken. The safest approach would be to have the insulation in the affected areas removed by a qualified environmental contractor.
For smaller jobs it may be sufficient to isolate work areas with temporary barriers or enclosures to avoid spreading fibers, use disposable protective clothing, and use proper respiratory protection. An important note – disposable respirators or dust masks are not appropriate for asbestos. Again, it is best to consult a qualified contractor.
The words are all-too-familiar to many homeowners. It is said that more than ninety-eight percent of all houses have had, or will have, basement leakage at some point.
Identifying the Problem:
The presence of efflorescence, a whitish mineral deposit on the interior of foundation walls, indicates moisture penetration. It should be noted that the severity of the problem, or whether the problem is active, is not indicated by the amount of efflorescence. Other clues are rusty nails in baseboards, rotted wood near floor level, rusted metal feet on appliances, mould and mildew, lifted floor tiles, storage on skids, peeling paint and the presence of dehumidifiers.
Poor surface drainage is one of the main causes of basement leaks. The ground should slope away from the house a rate of one inch per foot for at least the first six feet. As a preventative measure, seal where the driveway and sidewalk meet the foundation walls. The gutter and downspout systems must also perform properly. If downspouts are ever suspected of being disconnected, broken or clogged below ground level, they should be redirected to discharge above grade at least six feet away from the house. Also, gutters should be kept clear of debris.
Localized low areas including basement stairwells, window wells, et cetera, may allow water to collect. Drains should be provided in the bottom of these. Where there are no drains, plastic dome covers over the window wells allow light into the basement while minimizing water and snow accumulation.
More Extreme Measures:
In the vast majority of cases, basement leakage is not significant from a structural point of view and can be controlled relatively inexpensively, as discussed above. However, the presence of foundation cracks, damaged perimeter drainage tiles, a high water table or underground streams may call for more extreme corrective measures. These measures are used when chronic flooding occurs.
Sealing foundation cracks can be performed several ways with the cost of repairs varying. The approach taken depends on the specific crack; however, the most successful approach is sealing from the outside (Cost $500 - $900). Urethane or epoxy injection repairs can be done from the interior on poured concrete walls only (cost $400 - $600).
Excavating, dampproofing and installing drainage tiles should be used as a last resort. Dampproofing on the exterior typically involves parging a masonry foundation wall with a one-quarter inch layer of mortar covered with a bituminous or plastic membrane which extends down to the footings.
The drainage tile laid beside the footing is covered with gravel and filter paper. These tiles can often be damaged or clogged by roots and some localized repairs may be required.
Because excavating on the exterior is expensive ($8,000 - $15,000 typically), an alternative is an interior drainage system. The cost of this approach is one-third to one-quarter the cost of exterior work. There are many cases where this proves satisfactory, although this must be judged on a case by case basis.
Where underground streams and/or a high water table are present, sump pumps are usually required.
Hantavirus Danger in Homes
by Nick Gromicko, CMI® and Kenton Shepard
Hantavirus is the name commonly applied to the pathogen that causes the rare yet potentially deadly disease known as hantavirus cardiopulmonary syndrome (HPS).
HPS is actually caused by several forms of this virus which, collectively, account for just a fraction of all hantaviruses, most of which are not a threat to humans. For the purposes of this article, "hantavirus" refers only to the forms of that virus that can cause HPS.
This virus is transmitted through rodent feces, urine and saliva, and the primary mode of human contact with hantavirus is through inhalation. Crawlspaces and vacated houses are areas where rodent infestations are likely. Inspectors should be knowledgeable about the hantavirus so they can protect themselves and their clients.
Symptoms of HPS
Although researchers are not certain as to how long the virus’ incubation period may last, it is generally believed to last up to five weeks. Symptoms of HPS will follow this period.
Early symptoms of HPS almost always include muscle aches, fever and fatigue. Sufferers may also experience nausea, chills, dizziness, diarrhea, abdominal pain and headaches. Four to 10 days after these symptoms first appear, infected persons will find it hard to breathe as their lungs begin to fill with fluid. Coughing and shortness of breath are common respiratory symptoms of the later stages of infection.
There is no known cure, vaccine or treatment that specifically targets HPS. However, if the symptoms are recognized early, patients may benefit from oxygen therapy. If the symptoms of HPS are recognized late, it is less likely that medical intervention will be helpful. The hantavirus kills roughly 30% to 40% of those who become infected.
Places Where the Hantavirus is Likely to be Encountered
InterNACHI believes that crawlspaces are the most likely locations that the hantavirus may be encountered. This is partly due to the fact that rodents are attracted to areas that are undisturbed by humans. Also, crawlspaces are generally dark places that lack ultraviolet (UV) radiation, which can rapidly inactivate the hantavirus. The virus will be less likely to be dangerous in areas of the house that receive sunlight through windows. Open windows will also allow contaminants to vent from the home.
Homes that have not been occupied for long periods of time are more likely to experience heavy rodent infestation and hantavirus contamination, among other viruses and bacteria. Foreclosures, in particular, are problem areas. Inspectors should take special precautions when entering vacated homes, or areas in homes that are not adequately ventilated or exposed to sunlight.
The hantavirus can be transmitted to humans in the following ways:
- When fresh rodent droppings and urine that contains the hantavirus are disturbed, the virus will become airborne and can be more easily transmitted to humans. The majority of transmissions occur due to inhaled aerosolized droplets that are contaminated with hantavirus.
- Touching the nose or mouth after touching anything contaminated by infected rodents can lead to contamination and human infection.
- Eating food contaminated by infected rodents can transmit the virus.
- Although extremely rare, the virus can be transmitted through a bite from an infected rodent.
The hantavirus cannot be transmitted from infected humans to other humans, or to any other non-rodent animals.
If inspectors must enter a rodent-infested area of a house, they should wear personal protective equipment. The primary mode of transmission for hantavirus is through inhalation, so a respirator is necessary. The Centers for Disease Control (CDC) states that a half-face respirator is adequate, although other sources say that a full-face respirator (covering the eyes, nose and mouth) is required. To be safe, it is a good idea to wear goggles to prevent contaminated dust from coming into contact with the eyes if only a half-face respirator is being used.
The following are specific instructions from the CDC concerning appropriate respirators for hantavirus exposure:
Wear either a half-face, tight-seal, negative-pressure respirator, or a positive-pressure, powered air-purifying respirator (PAPR) equipped with N-100 or P-100 filters (formerly designated as high-efficiency particulate air filters [HEPA]). Negative-pressure respirators are not protective if facial hair interferes with the face-piece to face seal because a proper fit cannot be assured.
Rodents that Carry Hantavirus
Four species of mice and rats have been confirmed as carriers of the hantavirus. The CDC offers the following information to identify them:
1) The deer mouse is a deceptively cute animal, with big eyes and big ears. Its head and body are normally about 2 to 3 inches long, and the tail adds another 2 to 3 inches in length. You may see it in a variety of colors, from gray to reddish-brown, depending on its age. The underbelly is always white, and the tail has sharply defined white sides. The deer mouse is found almost everywhere in North America. Usually, the deer mouse likes woodlands, but also turns up in desert areas.
2) The cotton rat, which you'll find in the southeastern United States
(and way down into Central and South America), has a bigger body than the
deer mouse—the head and body are about 5 to 7 inches, and another 3 to 4
inches for the tail. The hair is longer and coarser, of a grayish-brown color,
even grayish-black. The cotton rat prefers overgrown areas with shrubs and tall
3) The rice rat is slightly smaller than the cotton rat, having a head and body 5 to 6 inches long, plus a very long, 4- to 7-inch tail. Rice rats sport short, soft, grayish-brown fur on top, and gray or tawny underbellies. Their feet are whitish. As you might expect from the name, this rat likes marshy areas and is semiaquatic. It's found in the southeastern United States and in Central America.
4) The white-footed mouse is hard to distinguish from the deer mouse. The head and body together are about 4 inches long. Note that its tail is normally shorter than its body (about 2 to 4 inches long). Topside, its fur ranges from pale brown to reddish-brown, while its underside and feet are white. The white-footed mouse is found throughout southern New England, the Mid-Atlantic and southern states, the midwestern and western states, and Mexico. It prefers wooded and brushy areas, although sometimes it will live in more open ground.
Although the virus can appear anywhere in the United States, it is more prevalent West of the Mississippi. Males and Caucasians are also somewhat more likely to contract HPS than females and other races, although it is likely that this occurrence is due to factors that are not gender- or ethnicity-specific, but are probably more attributable to occupational exposure and the higher frequency of Caucasians in the western United States.
It is possible that the virus can be carried by other species of rodents that have yet to be identified.
In summary, hantavirus should be taken seriously by every inspector because this virus is encountered in homes more than in any other location. The disease that it causes, HPS, has no cure, and very few people know enough about it to protect themselves from infection.
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