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December 8, 2006
This pamphlet is designed for members of the residential construction and remodeling industries, as well as owners and managers who work in affordable housing. It presents building guidance for both new construction and rehabilitation, as well as practices that can be used by property maintenance personnel.
The Building Connection
Housing and Asthma
Asthma is a serious disease that affects millions of Americans, particularly children. Asthma is also increasing at an alarming rate. Many air contaminants are found at higher levels indoors than outdoors. Among them are the most common asthma triggers: particles from molds, dust, mites, mice, rats, roaches and pets.
Indoor air contains other contaminants such as carbon monoxide, volatile organic compounds (chemicals released from materials), nitrogen dioxide, sulfur dioxide, radon and other particles that can also affect individuals.
Some indoor air contaminants come from outside (e.g. ozone, sulfur dioxide, carbon monoxide, pollens and other particles) and can also affect individuals.
How a unit is turned over and maintained has significant effects on the control of asthma triggers and other indoor and outdoor contaminants.
The Seven Steps to a Healthy Home
There are seven steps to a healthy home. A healthy home is:
- Well Ventilated
- Combustion Product Free
- Pest Free
- Toxic Chemical Free
Dry and Clean
Water, clutter and dust permit or encourage the growth of mold, insects, rodents and mites. Keeping a home dry controls mold and pests.
Ventilation provides a mechanism to remove contaminants.
Combustion Product Free
Combustion products such as carbon monoxide should not be present in a healthy home.
Toxic Chemical Free
Toxic cleaning compounds, pesticides, oil- or alkyd-based paints and solvents can lead to poor indoor air quality. Many of the containers these products are stored in slowly release the chemicals into the indoor air.
Pests lead to allergic reactions and pests lead to pesticides. Food and water lead to pests.
Uncomfortable homes can make people take action that makes a home unhealthy. A lack of comfort can lead to a lack of ventilation and over-humidification. If people are cold they won’t ventilate their home. If people can’t afford to heat their home they won’t ventilate their home. In the summertime, some people need to keep their windows closed because of outdoor pollutants such as pollen. If people are hot they’ll open their windows. If they open their windows they can’t filter the air. If they can’t filter the air they can’t keep out the pollen. If people are dry they’ll humidify. When they humidify they over-humidify. When they over-humidify they get mold.
It is important to determine the existing condition of the unit. What works, what doesn’t? Are there any leaking pipes? Are there any rain leakage issues? How about ground water? Are there any life-safety issues? Are there surfaces painted with lead-based paints? Is there asbestos?
Categorize the identified problems according to the seven steps:
- Well Ventilated
- Combustion Product Free
- Pest Free
- Toxic Chemical Free
Within each category prioritize the identified problems:
- Things that absolutely must be done because of life safety concerns or serious durability concerns;
- Things that should be done, but might not be done because they can’t be done for program reasons (money, time, etc.);
- Things that are a good idea, but we might not get around to this time.
Do the things that absolutely must be done, and then as many of the others as you can do within program limitations.
Water is a precondition for mold, insects, rodents, dust mites and is arguably the most important factor in the design and construction of a healthy home. Water is also the most important factor affecting the durability of a home and the most important factor affecting maintenance costs.
Control Water = Control
The three most important sources of water requiring control are:
- Ground Water
- Plumbing Leaks
Make sure the roof doesn’t leak. If it does fix it. Make sure that the windows and doors don’t leak. If they do fix them. Remember in all of the fix strategies that caulking and sealants are temporary and should not be used unless there are no other options. Using flashings and drainage pans are the preferred methods of rain control.
Keep ground water out of foundations. If the basement leaks fix it. The fundamental principles of ground water control are to keep rainwater away from the foundation wall perimeter and to drain groundwater with sub-grade perimeter drains before it gets to the foundation wall. Make sure that the ground slopes away from the foundation. Make sure that gutters drain away from the foundation. Make sure that gutters and downspouts are clean and connected.
Plumbing leaks need to be fixed. Check clothes washers and hot water heaters. Make sure there are shut off valves. The rubber hose connections to clothes washers are prone to failure. Check them carefully and replace them frequently. Better still, replace with metal reinforced hoses.
If there is a clothes dryer, vent it to the outside.
Make sure that the bathroom and kitchen fans work. If there are no bathroom or kitchen fans see if you can get some installed.
Basements are often damp. Make sure that there is nothing in a damp basement that can decay. Get rid of all cellulose based materials (paper, cardboard boxes, gypsum board, wood). Remove all the wood that you can that touches below grade walls and floors. Make sure that subsequent tenants don’t store anything in a damp basement. Provide alternative storage areas whenever possible. One trick to reduce evaporation into a basement that often works is painting the floor with a latex based concrete floor paint (not an epoxy). You want a paint that breathes a little – not a paint that is a perfect barrier because it will blister.
If you have a crawlspace make sure that the crawlspace has a complete continuous polyethylene ground cover.
If you have a damp basement install a dehumidifier. Don’t open basement windows in the summertime to try to dry it out, the basement will only get wetter. Outside air in the summertime is humid and the water in the air will condense on cold basement walls.
It’s important that attics are well ventilated. Make sure that there are attic vents at both the soffit and ridge. And make sure the vents are not blocked with insulation.
And finally get rid of any and all wallpaper. Wallpaper keeps walls from drying if they get wet; vinyl wallpaper is even worse. Paint walls, don’t use wallpaper.
On the outside make sure that all wood siding is painted. Especially the bottom edges of trim. Replace any rotted trim with backprimed trim – with all ends and field cuts sealed.
Absolutely, no installed carpet in areas prone to get wet: bathrooms, laundry rooms, kitchens, entryways and damp basements.
Before you turn over a unit, thoroughly clean the unit, especially areas that are hard to reach.
Over two thirds of dust in homes originates outdoors, and is tracked in on feet. House dust is known to contain many hazardous materials including pesticides and lead. House dust contains many asthma triggers.
It is important to stop the dust at the door. A three part track-off approach is recommended:
- Permeable, rugged outdoor mat that collects gritty materials; a grate over a collection hole is an alternative approach
- Rugged indoor mat that collects grit and water; and
- A hard surface, easily mopped floor to collect very fine particles left by drying foot prints.
Whenever possible, replace carpets with washable flooring. Use window treatments such as blinds or shades that can be easily wiped. Use hard surfaces rather than textiles. Use semi-gloss paints instead of flat or matte finishes. Such surfaces are easier to clean using mild soaps.
Change the furnace filter regularly . Filters should be rated at MERV 6-8 (35 percent or better dust spot efficiency).
Indoor humidity and airborne contaminants are both controlled by ventilation. There are two kinds of ventilation: spot ventilation and dilution ventilation. Both are necessary in a healthy home. Spot ventilation deals with point sources of contamination such as bathrooms and kitchens. Dilution ventilation deals with low level contamination throughout the home.
Every home requires exhaust to the outside from bathrooms and from kitchens. In kitchens, recirculating fans should be avoided because they can become breeding grounds for biologicals, a major source of odors, and in all cases allow grease vapors to coat surfaces throughout the home, plus they don’t remove moisture.
All bathrooms require exhaust fans ducted to the outside – even bathrooms with operable windows. No exceptions. When fans are replaced, use low sone fans (less than 3 sones) because they are quiet and more durable.
Dilution ventilation can be provided three ways: exhaust, supply or balanced. In all cases it should be continuous and fan powered.
To reduce formaldehyde emissions (an irritant and asthma trigger) from particleboard surfaces, reduce the amount of particleboard. Use wire shelving in closets. Wire shelving is easy to clean and permits air circulation. With kitchen and bathroom cabinets constructed from particleboard, seal the exposed particleboard surfaces with 100 percent acrylic paint. . .
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