Basic Waterproofing for Basements

by Nick Gromico and Ethan Ward

Water Damage Concerns

Basements are typically the area of a structure most at risk for water damage because they are located below grade and surrounded by soil.  Soil releases water it has absorbed during rain or when snow melts, and the water can end up in the basement through leaks or cracks.  Water can even migrate through solid concrete walls via capillary action, which is a phenomenon whereby liquid spontaneously rises in a narrow space, such as a thin tube, or via porous materials.  Wet basements can cause problems that include peeling paint, toxic mold contamination, building rot, foundation collapse, and termite damage.  Even interior air quality can be affected if naturally occurring gasses released by the soil are being transmitted into the basement.

Properly waterproofing a basement will lessen the risk of damage caused by moisture or water.  Homeowners will want to be aware of what they can do to keep their basements dry and safe from damage.  Inspectors can also benefit from being aware of these basic strategies for preventing leaks and floods.

Prevent water entry by diverting it away from the foundation.

Preventing water from entering the basement by ensuring it is diverted away from the foundation is of primary concern.  Poor roof drainage and surface runoff due to gutter defects and improper site grading may be the most common causes of wet basements.  Addressing these issues will go a long way toward ensuring that water does not penetrate the basement.

Here are some measures to divert water away from the foundation:

• Install and maintain gutters and downspouts so that they route all rainwater and snow melt far enough away from the foundation of the building to ensure that pooling does not occur near the walls of the structure.  At least 10 feet from the building is best, and at the point where water leaves the downspout, it should be able to flow freely away from the foundation instead of back toward it, and should not be collecting in pools.
• The finish grade should be sloped away from the building for 10 to 15 feet.  Low spots that may lead to water pooling should be evened out to prevent the possibility of standing water near the foundation.
• Shallow ditches called swales should be used in conditions where one or more sides of the building face an upward slope.  A swale should slope away from the building for 10 to 15 feet, at which point it can empty into another swale that directs water around to the downhill-side of the building, leading it away from the foundation.

 

Repair all cracks and holes.

If leaks or seepage is occurring in the basement’s interior, water and moisture are most likely entering through small cracks or holes.  The cracks or holes could be the result of several things.  Poor workmanship during the original build may be making itself apparent in the form of cracks or holes.  Water pressure from the outside may be building up, forcing water through walls.  The house may have settled, causing cracks in the floor or walls.  Repairing all cracks and small holes will help prevent leaks and floods.

Here are some steps to take if you suspect that water is entering the basement through cracks or holes:

• Identify areas where water may be entering through cracks or holes by checking for moisture, leaking or discoloration.  Every square inch of the basement should be examined, especially in cases where leaking or flooding has not been obvious, but moisture buildup is readily apparent.
• A mixture of epoxy and latex cement can be used to fill small hairline cracks and holes.  This is a waterproof formula that can help ensure that moisture and water do not penetrate basement walls.  It is effective primarily for very small cracks and holes.
• Any cracks larger than about 1/8-inch should be filled with mortar made from one part cement and two parts fine sand, with just enough water to make a fairly stiff mortar.  It should be pressed firmly into all parts of the larger cracks and holes to be sure that no air bubbles or pockets remain.  As long as water is not being forced through basement walls due to outside pressure, the application of mortar with a standard trowel will be sufficient if special care is taken to fill all cracks completely.
• If water is being forced through by outside pressure, a slightly different method of patching with mortar can be used.  Surface areas of walls or floors with cracks should first be chiseled out a bit at the mouth of the crack and all along its length.  Using a chipping chisel and hammer or a cold chisel, cut a dovetail groove along the mouth of each crack to be filled, and then apply the mortar thoroughly.  The dovetail groove, once filled, should be strong enough to resist the force of pressure that was pushing water through the crack.

Apply sodium-silicate sealant to the walls and floor.

Once all runoff has been thoroughly diverted away from the foundation, and all cracks and holes have been repaired and no leaking is occurring, a waterproof sealant can be applied as a final measure.

Sodium silicate is a water-based mixture that will actually penetrate the substrate by up to 4 inches.  Concrete, concrete block and masonry have lime as a natural component of their composition, which reacts with the sodium silicate to produce a solid, crystalline structure which fills in all the microscopic cracks, holes and pores of the substrate.  No water vapor or gas will be able penetrate via capillary action because the concrete and masonry have now become harder and denser from the sodium silicate.

Here are some steps and tips for its application:

• Special care should be taken when applying sodium silicate.  It is an alkaline substance and, as such, can burn skin and eyes if it comes into contact with them.  Inhalation can also cause irritation to the respiratory tract.

  

• Sodium silicate must be applied only to bare concrete, concrete block or masonry that has been cleaned thoroughly and is free of any dirt, oil, adhesives, paint and grease.  This will ensure that it penetrates the substrate properly and fills in all microscopic cracks.  It can be applied using a garden sprayer, roller or brush to a surface that has first been lightly dampened with a mop or brush.  Apply two to three coats to the concrete, waiting 10 to 20 minutes between each application.  Concrete block and masonry will take three to four coats, with the same 10 to 20 minutes between applications.  Any excess should then be wiped away.  Sodium silicate should not be over-applied or it will not be completely absorbed by the substrate, leaving a white residue.
• Paint can then be applied without fear of water vapor getting trapped between the paint and the wall, which could eventually cause blistering and peeling.  Adhesives for tile or floor covering can also be used more effectively, once the substrate has been sealed.

Diverting water away from foundations so that it does not collect outside basement walls and floors is a key element in preventing flooding and water damage.  Ensuring that any water that does end up near basement exteriors cannot enter through holes or cracks is also important, and sealing with a waterproof compound will help prevent water vapor or gas from penetrating, as well.  By following these procedures, the risk of water-related issues in basement interiors can be greatly reduced, protecting the building from damage such as foundation rotting, mold growth, and peeling paint, as well as improving the interior air quality by blocking the transmission of gasses from the soil outside.

Ungrounded Electrical Receptacles

by Nick Gromicko and Rob London

Grounding of electrical receptacles (which some laypeople refer to as outlets) is an important safety feature that has been required in new construction since 1962, as it minimizes the risk of electric shock and protects electrical equipment from damage. Modern, grounded 120-volt receptacles in the United States have a small, round ground slot centered below two vertical hot and neutral slots, and it provides an alternate path for electricity that may stray from an appliance. Older homes often have ungrounded, two-slot receptacles that are outdated and potentially dangerous. Homeowners sometimes attempt to perform the following dangerous modifications to ungrounded receptacles:

• the use of an adapter, also known as a “cheater plug.” Adapters permit the ungrounded operation of appliances that are designed for grounded operation. These are a cheaper alternative to replacing ungrounded receptacles, but are less safe than properly grounding the connected appliance;
• replacing a two-slot receptacle with a three-slot receptacle without re-wiring the electrical system so that a path to ground is provided to the receptacle. While this measure may serve as a seemingly proper receptacle for three-pronged appliances, this “upgrade” is potentially more dangerous than the use of an adapter because the receptacle will appear to be grounded and future owners might never be aware that their system is not grounded. If a building still uses knob-and-tube wiring, it is likely than any three-slot receptacles are ungrounded. To be sure, InterNACHI inspectors may test suspicious receptacles for grounding; and
• removal of the ground pin from an appliance. This common procedure not only prevents grounding but also bypasses the appliance’s polarizing feature, since a de-pinned plug can be inserted into the receptacle upside-down.

While homeowners may be made aware of the limitations of ungrounded electrical receptacles, upgrades are not necessarily required. Many small electrical appliances, such as alarm clocks and coffee makers, are two-pronged and are thus unaffected by a lack of grounding in the building’s electrical system.

Upgrading the system will bring it closer to modern safety standards, however, and this may be accomplished in the following ways:

• Install three-slot receptacles and wire them so that they’re correctly grounded.
• Install ground-fault circuit interrupters (GFCIs). These can be installed upstream or at the receptacle itself. GFCIs are an accepted replacement because they will protect against electric shocks even in the absence of grounding, but they may not protect the powered appliance. Also, GFCI-protected ungrounded receptacles may not work effectively with surge protectors. Ungrounded GFCI-protected receptacles should be identified with labels that come with the new receptacles that state:  “No Equipment Ground.”
• Replace three-slot receptacles with two-slot receptacles. Two-slot receptacles correctly represent that the system is ungrounded, lessening the chance that they will be used improperly.

Homeowners and non-qualified professionals should never attempt to modify a building’s electrical components. Misguided attempts to ground receptacles to a metallic water line or ground rod may be dangerous. InterNACHI inspectors may recommend that a qualified electrician evaluate electrical receptacles and wiring.

In summary, adjustments should be made by qualified electricians — not homeowners — to an electrical system to upgrade ungrounded receptacles to meet modern safety standards and the requirements of today’s typical household appliances.

Wood-Burning Stoves

by Nick Gromicko and Rob London

A wood-burning stove (also known as a wood stove) is a heating appliance made from iron or steel that is capable of burning wood fuel. Unlike standard fireplaces, wood stoves are typically contained entirely within the living space, rather than inset in the wall.

Wood stoves come in many different sizes, each suited for a different purpose:

• Small stoves are suitable in single rooms, seasonal cottages or small, energy efficient homes. These models can also be used for zone heating in large homes where supplemental heating is needed.
• Medium-size stoves are appropriate for heating small houses or mid-size homes that are intended to be energy-efficient and as inexpensive as possible to maintain.
• Large stoves are used in larger homes or older homes that leak air and are located in colder climate zones.

To ensure safe and efficient use of wood-burning stoves, inspectors can pass along the following tips to their clients:

Never:

• burn coal. Coal burns significantly hotter than wood, posing a fire hazard;
• burn materials that will emit toxic chemicals, such as wood that has been pressure-treated or painted, colored paper, gift wrap, plastic, plywood, particleboard, or questionable wood from furniture;
• burn wet wood. Generally speaking, it takes six months for cut, stored wood to dry out and be ready for use in wood-burning stoves;
• burn combustible liquids, such as kerosene, gasoline, alcohol or lighter fluid;
• let small children play near a lit wood-burning stove. Unlike standard fireplaces, the sides of which are mostly inaccessible, all sides of wood stoves are exposed and capable of burning flesh or clothing; or
• let the fire burn while the fire screen or door is open.

Always:

• use a grate to hold the logs so that they remain secured in the stove and the air can circulate adequately to keep the fire burning hot;
• keep the damper open while the stove is lit;
• dispose of ashes outdoors in a water-filled, metal container;
• check smoke alarms to make sure they are working properly; and
• periodically remove the stovepipe between the stove and the chimney so that it can be inspected for creosote. Homeowners may want to hire a professional to perform this service.

Efficiency and Air Pollutants

While federal and state governments crack down on vehicle and industrial emissions, they do relatively little to limit the harmful air pollution emitted from wood stoves. The problem is so bad that, in many areas, such as Chico, Caifornia (pictured at right), the smoke from wood stoves is the largest single contributor to that city’s air pollution.  Smoke from wood stoves can cause a variety of health ailments, from asthma to cancer.

To mitigate these concerns, the EPA sets requirements for wood-stove emissions based on the design of the stove: 4.1 grams of smoke per hour (g/h) for catalytic stoves, and 7.5 g/h for non-catalytic stoves. Some state laws further restrict airborne particulates, and many new models emit as little as 1 g/h. These two approaches — catalytic and non-catalytic combustion — are described briefly as follows:

• In catalytic stoves, the smoky exhaust passes through a coated, ceramic honeycomb that ignites particulates and smoke gasses. Catalysts degrade over time and must eventually be replaced, but they can last up to six seasons if the stove is used properly. Inadequate maintenance and the use of inappropriate fuel result in an early expiration of the catalyst. These stoves are typically more expensive than non-catalytic models, and they require more maintenance, although these challenges pay off through heightened efficiency.
• Non-catalytic stoves lack a catalyst but have three characteristics that assist complete, clean combustion:  pre-heated combustion air introduced from above the fuel; firebox insulation; and a large baffle to create hotter, longer air flow in the firebox. The baffle will eventually need to be replaced as it deteriorates from combustion heat.

The following indicators hint that the fire in a wood-burning stove suffers from oxygen deprivation and incomplete combustion, which will increase the emission of particulates into the air:

• It emits dark, smelly smoke. An efficient stove will produce little smoke.
• There is a smoky odor in the house.
• There is soot on the furniture.
• The stove is burning at less than 300º F. A flue pipe-mounted thermometer should read between 300º F and 400º F.
• The flames are dull and steady, rather than bright and lively.

To ensure efficiency, practice the following techniques:

• Purchase a wood-burning stove listed by Underwriters Laboratories. Stoves tested by UL and other laboratories burn cleanly and efficiently.
• Burn only dry wood. Wood that has a moisture content (MC) of less than 20% burns hotter and cleaner than freshly cut wood, which may contain half of its weight in water.
• Burn hardwoods, such as oak, hickory and ash once the fire has started. Softwoods, such as pine, ignite quicker and are excellent fire starters.
• Make sure the stove is properly sized for the space. Stoves that are too large for their area burn inefficiently.
• Burn smaller wood rather than larger pieces. Smaller pieces of wood have a large surface area, which allows them to burn hotter and cleaner.

In summary, wood-burning stoves, if properly designed and used appropriately for the space, are efficient, clean ways to heat a home.

Aluminum Wiring

by Nick Gromicko, Rob London and Kenton Shepard

Between approximately 1965 and 1973, single-strand aluminum wiring was sometimes substituted for copper branch-circuit wiring in residential electrical systems due to the sudden escalating price of copper. After a decade of use by homeowners and electricians, inherent weaknesses were discovered in the metal that lead to its disuse as a branch wiring material. Although properly maintained aluminum wiring is acceptable, aluminum will generally become defective faster than copper due to certain qualities inherent in the metal. Neglected connections in outlets, switches and light fixtures containing aluminum wiring become increasingly dangerous over time. Poor connections cause wiring to overheat, creating a potential fire hazard. In addition, the presence of single-strand aluminum wiring may void a home’s insurance policies. Inspectors may instruct their clients to talk with their insurance agents about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy language.

Facts and Figures

• On April, 28, 1974, two people were killed in a house fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet.
• According to the Consumer Product Safety Commission (CPSC), “Homes wired with aluminum wire manufactured before 1972 [‘old technology’ aluminum wire] are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than is a home wired with copper.”

Aluminum as a Metal

Aluminum possesses certain qualities that, compared with copper, make it an undesirable material as an electrical conductor. These qualities all lead to loose connections, where fire hazards become likely. These qualities are as follows:

• higher electrical resistance. Aluminum has a high resistance to electrical current flow, which means that, given the same amperage, aluminum conductors must be of a larger diameter than would be required by copper conductors.
• less ductile. Aluminum will fatigue and break down more readily when subjected to bending and other forms of abuse than copper, which is more ductile. Fatigue will cause the wire to break down internally and will increasingly resist electrical current, leading to a buildup of excessive heat.
• galvanic corrosion.  In the presence of moisture, aluminum will undergo galvanic corrosion when it comes into contact with certain dissimilar metals.
• oxidation. Exposure to oxygen in the air causes deterioration to the outer surface of the wire. This process is called oxidation. Aluminum wire is more easily oxidized than copper wire, and the compound formed by this process – aluminum oxide – is less conductive than copper oxide. As time passes, oxidation can deteriorate connections and present a fire hazard.
• greater malleability. Aluminum is soft and malleable, meaning it is highly sensitive to compression. After a screw has been over-tightened on aluminum wiring, for instance, the wire will continue to deform or “flow” even after the tightening has ceased. This deformation will create a loose connection and increase electrical resistance in that location.
• greater thermal expansion and contraction. Even more than copper, aluminum expands and contracts with changes in temperature. Over time, this process will cause connections between the wire and the device to degrade. For this reason, aluminum wires should never be inserted into the “stab,” “bayonet” or “push-in” type terminations found on the back of many light switches and outlets.
• excessive vibration. Electrical current vibrates as it passes through wiring. This vibration is more extreme in aluminum than it is in copper, and, as time passes, it can cause connections to loosen.

Identifying Aluminum Wiring

• Aluminum wires are the color of aluminum and are easily discernible from copper and other metals.
• Since the early 1970s, wiring-device binding terminals for use with aluminum wire have been marked CO/ALR, which stands for “copper/aluminum revised.”
• Look for the word “aluminum” or the initials “AL” on the plastic wire jacket. Where wiring is visible, such as in the attic or electrical panel, inspectors can look for printed or embossed letters on the plastic wire jacket. Aluminum wire may have the word “aluminum,” or a specific brand name, such as “Kaiser Aluminum,” marked on the wire jacket. Where labels are hard to read, a light can be shined along the length of the wire.
• When was the house built? Homes built or expanded between 1965 and 1973 are more likely to have aluminum wiring than houses built before or after those years.

Options for Correction

Aluminum wiring should be evaluated by a qualified electrician who is experienced in evaluating and correcting aluminum wiring problems. Not all licensed electricians are properly trained to deal with defective aluminum wiring. The CPSC recommends the following two methods for correction for aluminum wiring:

• Rewire the home with copper wire. While this is the most effective method, rewiring is expensive and impractical, in most cases.
• Use copalum crimps. The crimp connector repair consists of attaching a piece of copper wire to the existing aluminum wire branch circuit with a specially designed metal sleeve and powered crimping tool. This special connector can be properly installed only with the matching AMP tool. An insulating sleeve is placed around the crimp connector to complete the repair. Although effective, they are expensive (typically around $50 per outlet, switch or light fixture).

Although not recommended by the CPSC as methods of permanent repair for defective aluminum wiring, the following methods may be considered:

• application of anti-oxidant paste. This method can be used for wires that are multi-stranded or wires that are too large to be effectively crimped.
• pigtailing. This method involves attaching a short piece of copper wire to the aluminum wire with a twist-on connector. the copper wire is connected to the switch, wall outlet or other termination device. This method is only effective if the connections between the aluminum wires and the copper pigtails are extremely reliable. Pigtailing with some types of connectors, even though Underwriters Laboratories might presently list them for the application, can lead to increasing the hazard. Also, beware that pigtailing will increase the number of connections, all of which must be maintained. Aluminum Wiring Repair (AWR), Inc., of Aurora, Colorado, advises that pigtailing can be useful as a temporary repair or in isolated applications, such as the installation of a ceiling fan.
• CO/ALR connections. According to the CPSC, these devices cannot be used for all parts of the wiring system, such as ceiling-mounted light fixtures or permanently wired appliances and, as such, CO/ALR connections cannot constitute a complete repair. Also, according to AWR, these connections often loosen over time.
• alumiconn. Although AWR believes this method may be an effective temporary fix, they are wary that it has little history, and that they are larger than copper crimps and are often incorrectly applied.
• Replace certain failure-prone types of devices and connections with others that are more compatible with aluminum wire.
• Remove the ignitable materials from the vicinity of the connections.

In summary, aluminum wiring can be a fire hazard due to inherent qualities of the metal. Inspectors should be capable of identifying this type of wiring.

Protect Your Property From Water Damage

Water may be essential to life, but, as a destructive force, water can diminish the value of your home or building. Homes as well as commercial buildings can suffer water damage that results in increased maintenance costs, a decrease in the value of the property, lowered productivity, and potential liability associated with a decline in indoor air quality. The best way to protect against this potential loss is to ensure that the building components which enclose the structure, known as the building envelope, are water-resistant. Also, you will want to ensure that manufacturing processes, if present, do not allow excess water to accumulate. Finally, make sure that the plumbing and ventilation systems, which can be quite complicated in buildings, operate efficiently and are well-maintained. This article provides some basic steps for identifying and eliminating potentially damaging excess moisture.

Identify and Repair All Leaks and Cracks

The following are common building-related sources of water intrusion:

• windows and doors: Check for leaks around your windows, storefront systems and doors.
• roof: Improper drainage systems and roof sloping reduce roof life and become a primary source of moisture intrusion. Leaks are also common around vents for exhaust or plumbing, rooftop air-conditioning units, or other specialized equipment.
• foundation and exterior walls: Seal any cracks and holes in exterior walls, joints and foundations. These often develop as a naturally occurring byproduct of differential soil settlement.
• plumbing: Check for leaking plumbing fixtures, dripping pipes (including fire sprinkler systems), clogged drains (both interior and exterior), defective water drainage systems and damaged manufacturing equipment.
• ventilation, heating and air conditioning (HVAC) systems: Numerous types, some very sophisticated, are a crucial component to maintaining a healthy, comfortable work environment. They are comprised of a number of components (including chilled water piping and condensation drains) that can directly contribute to excessive moisture in the work environment. In addition, in humid climates, one of the functions of the system is to reduce the ambient air moisture level (relative humidity) throughout the building. An improperly operating HVAC system will not perform this function.

Prevent Water Intrusion Through Good Inspection and Maintenance Programs

Hire a qualified InterNACHI inspector to perform an inspection of the following elements of your building to ensure that they remain in good condition:

• flashings and sealants: Flashing, which is typically a thin metal strip found around doors, windows and roofs, are designed to prevent water intrusion in spaces where two building materials come together. Sealants and caulking are specifically applied to prevent moisture intrusion at building joints. Both must be maintained and in good condition.
• vents: All vents should have appropriate hoods, exhaust to the exterior, and be in good working order.
• Review the use of manufacturing equipment that may include water for processing or cooling. Ensure wastewater drains adequately away, with no spillage. Check for condensation around hot or cold materials or heat-transfer equipment.
• HVAC systems are much more complicated in commercial buildings. Check for leakage in supply and return water lines, pumps, air handlers and other components. Drain lines should be clean and clear of obstructions. Ductwork should be insulated to prevent condensation on exterior surfaces.
• humidity: Except in specialized facilities, the relative humidity in your building should be between 30% and 50%. Condensation on windows, wet stains on walls and ceilings, and musty smells are signs that relative humidity may be high. If you are concerned about the humidity level in your building, consult with a mechanical engineer, contractor or air-conditioning repair company to determine if your HVAC system is properly sized and in good working order. A mechanical engineer should be consulted when renovations to interior spaces take place.
• moist areas: Regularly clean off, then dry all surfaces where moisture frequently collects.
• expansion joints: Expansion joints are materials between bricks, pipes and other building materials that absorb movement. If expansion joints are not in good condition, water intrusion can occur.

Protection From Water Damage

• interior finish materials: Replace drywall, plaster, carpet and stained or water-damaged ceiling tiles. These are not only good evidence of a moisture intrusion problem, but can lead to deterioration of the work environment, if they remain over time.
• exterior walls: Exterior walls are generally comprised of a number of materials combined into a wall assembly. When properly designed and constructed, the assembly is the first line of defense between water and the interior of your building. It is essential that they be maintained properly (including regular refinishing and/or resealing with the correct materials).
• storage areas: Storage areas should be kept clean.  Allow air to circulate to prevent potential moisture accumulation.

Act Quickly if  Water Intrusion Occurs

Label shut-off valves so that the water supply can be easily closed in the event of a plumbing leak. If water intrusion does occur, you can minimize the damage by addressing the problem quickly and thoroughly. Immediately remove standing water and all moist materials, and consult with a building professional. Should your building become damaged by a catastrophic event, such as fire, flood or storm, take appropriate action to prevent further water damage, once it is safe to do so. This may include boarding up damaged windows, covering a damaged roof with plastic sheeting, and/or removing wet materials and supplies. Fast action on your part will help minimize the time and expense for repairs, resulting in a faster recovery.



Vermiculite

by Nick Gromicko and Rob London

Vermiculite is a naturally occurring mineral composed of shiny flakes that resemble mica. When heated rapidly to a high temperature, this crystalline mineral expands into low-density, accordion-like strands. In this form, vermiculite is a lightweight, odorless and fire-resistant material that has been used in numerous applications, such as insulation for attics and walls.

Asbestos Contamination

Vermiculite forms over millions of years due to weathering of the mineral biotite. Unfortunately, biotite deposits are often in close proximity to deposits of diopside, which transform into asbestos due to the same weathering processes that create vermiculite. Asbestos can be easily inhaled because it tends to separate into microscopic particles that become airborne. Exposure to asbestos can result in lung cancer, mesothelioma, inflammation of the chest cavity, and a scarring disease of the lungs known as asbestosis. The risk of contracting these diseases generally increases with the duration and intensity of exposure to asbestos, and smokers may face an even greater risk of lung cancer.

The largest and oldest vermiculite mine in the United States was started in the 1920s near Libby, Montana. Although it was known that the vermiculite there was contaminated with tremolite, a highly toxic form of asbestos, the mine continued to operate until stiffer environmental controls finally forced it to close in 1990. Sadly, by this time, the damage had already been done; the asbestos-infused insulator had been installed in tens of millions of homes in the United States alone. As over 70% of all vermiculite sold in the U.S. from 1919 to 1990 originated from the Libby mine, it is safe to assume that all vermiculite insulation found in buildings is toxic.

Identification

Vermiculite insulation is a pebble-like or rectangular, chunky product about the size of a pencil eraser, and usually gray-brown or silver-gold in color. Inspectors should be on guard for empty bags in the attic that bear the name Zonolite®, as this was the commercial name for vermiculite mined in the notorious Libby mine.

What should be done about asbestos found in homes?

Inspectors should advise their clients to never disturb vermiculite or any asbestos insulation. These products must be airborne to cause a health risk through inhalation, which most likely happens when they are removed or handled. The following are some additional tips that inspectors can pass on to clients with vermiculite issues:

• Consider that contractors may track vermiculite into the house if they have to enter the attic.
• Dispose of waste and debris contaminated with asbestos in tight containers.
• Do not allow children to play in an attic.
• Do not launder clothing exposed to vermiculite with family clothing.
• Do not overreact. According to the National Institute for Occupational Safety and Health (OSHA), asbestos-related illnesses are usually the result of high levels of exposure for long periods of time. Left undisturbed in the attic, asbestos is generally not a life-threatening situation. Furthermore, air generally flows into the attic from the house, and not the other way around.
• Do not use the attic as a storage area.
• Hire a professional asbestos contractor before remodeling or renovating if these processes may disturb the vermiculite.
• Never use compressed air for cleaning around vermiculite. Avoid dry-sweeping, vacuuming, shoveling, or other dry clean-up methods. Wet methods are best.
• Seal cracks and holes in attics, such as around light fixtures and ceiling fans, where insulation may pass through.
• Use proper respiratory protection. Disposable respirators or dust masks are not appropriate for avoiding asbestos exposure.

In summary, vermiculite is a potentially hazardous mineral used as an insulator in buildings, but its dangers can be mitigated with some simple precautions.