BSP-040: READ THIS: Before You Design, Build or Renovate

Carbon monoxide (CO) is a major health threat in homes. If fuel-burning appliances do not operate properly, they can produce carbon monoxide. However, CO poisoning is preventable. If combustion appliances are installed in homes, occupants should be educated about the health effects and symptoms of CO poisoning, and CO monitors should be installed in the home.

When something is burned it produces combustion by-products — particularly carbon monoxide and soot — that are unhealthy.  Even “clean” burning flames produce large quantities of water vapor, nitrogen oxides, sulfur oxides and carbon dioxide, all of which can lead to problems for people. Combustion by-products should not be found in the indoor air of a healthy home.

Combustion Appliances

Gas cook tops and gas ovens produce combustion by-products.  These appliances can be large sources of carbon monoxide. Gas cook tops and gas ovens should only be used in combination with exhaust ventilation.  Even with exhaust ventilation, some individuals with asthma and other respiratory diseases can be adversely affected. Electric ranges and ovens combined with exhaust ventilation may be the only option for these individuals. All cook tops and ovens should be installed with range fans that are exhausted to the exterior. In addition, contractors should testnew gas appliances for carbon monoxide during installation and prior to use by the occupants.

Gas furnace, gas boiler and gas water heater vent systems should not communicate with occupied spaces.  They should always be sealed-combustion or power-vented devices (see Figure 43).

Fireplaces must be vented to the exterior. Ventless gas fireplaces should never be installed. Large exhaust fans (clothes dryer, kitchen range hood) can backdraft fireplaces and wood stoves orinduce spillage of smoke and soot into the house. Operating large exhaust fans should be avoided during fireplace and wood stove use.  Fireplaces and other combustion appliances that are not direct-vent sealed combustion should be performance tested annually to ensure the products ofcombustion are exhausted from the home.

Leaky or disconnected ducts in forced heating and cooling systems can also lead to sufficiently large negative pressures to backdraft and spill fireplaces, wood stoves and other combustion appliances. Using building cavities as returns such as planned floor joists should be avoided since they are impossible to seal airtight.

Garages

Ideally, garages should not be connected to a healthy home.  Discrete, separate garages constructed away from homes are preferred. If garages are connected to a home, they should be ventilated to the exterior with a passive vent stack (a “chimney” to the outside — 6 inch duct). Air-handling devices such as furnaces or air conditioners should never be located in garages.  Nor should forced air ductwork.  Weatherstrip the door between the garage and the home and air seal the common wall.

When ductwork passes through a chase or a floor above a garage or adjacent to an exterior wall bordering a garage, it is important that the ductwork be sealed airtight against the migration of pollutants from the garage to inside the home.

Dust

Stop the dust at the door.  Vacuum and filter the rest away. And make it easy to clean.

Over two-thirds of dust in houses originates outdoors, and is tracked in on feet.  House dust is known to contain many hazardous materials, and it is an asthma trigger.

Entry Control

Pave exterior walks.  Use exterior grate track off, interior carpet mat and hard surface floors. Design entries so that there is room to remove and store coats, shoes and boots. A three part track-off approach uses:

1. Permeable, rugged outdoor mat that collects gritty materials (or a grate over a collection hole);
2. Rugged indoor mats that collect grit and water; and
3. Hard-surface, easily mopped floors to collect very fine particles left by drying footprints.

Lead Dust Control

Homes built before 1978 may contain lead-based paint. Renovation jobs that cut, saw, demolishor sand paint may create lead hazards. Lead may damage the nervous system causing learning andbehavior problems. To minimize the risk of creating dust, follow the steps described in the Lead Paint Safety Field Guide, which can be obtained from www.hud.gov/offices/lead. This web site also contains information about the Lead-Based Paint Disclosure and Lead-Safe Housing regulations.

Cleanable Surfaces

Whenever possible, replace carpets with smooth flooring, which is easy to clean and less likely toretain dust.  Use window treatments such as blinds or shades that can be easily wiped.  Use hard surfaces rather than textiles.  Use semi-gloss latex paints instead of flat or matte finishes because such surfaces are easier to clean using mild soaps.

Filtration

Construct a tight building enclosure to keep out outside dust and provide filtration.  Filters should be MERV 6 – 8 (35 percent or better ASHRAE dust spot efficiency).

Pests

Infestations of cockroaches, dust mites, mice and rats can all cause allergic reactions.  Even after the pests are gone, their skin, hair and feces can remain and can trigger allergic reactions.

Making a home pest-resistant produces a healthier home in two ways:  it reduces exposure to allergens and asthma triggers released by the pests, and it can reduce the amount of pesticides used by the occupants.

Design and construct the building so it’s easy for people to keep pests from colonizing. Take thefollowing steps:

• Make it hard for pests to get in by sealing the walls, ceilings, roofs and foundations.
• If they do get in, make it hard for pests to move around unseen by sealing passages through interior floors, walls and ceilings and kick spaces.
• Make it hard for pests to find water by keeping liquid water out, making plumbing easy to inspect and repair and insulating plumbing pipes to keep them warm (above dewpoint temperatures).
• Make it hard for pests to find food using tight food storage, keeping paper and wood products away from potential moisture sources and using pest-resistant materials.
• Make directed use of low-toxicity pesticides in locations that are heavily infested with problem pests.

To Know the Critter Is to Control The Critter

To actually do the things on the list, know the pest. The simplest, safest and most elegant controlsare those that work with the pest’s natural urges. Pests that get eaten a lot don’t like open spaces.Give them open spaces, with no closed-in kick spaces, such as strips around buildings free ofshrubs and organic mulch. Seal around pipes and wires to keep them out of walls.

Keeping Them Out

Keep pests out by changing the surrounding landscape and by blocking entries and passages. Reduce food and water availability.

Keep bushes and trees at least 3 feet from homes. Bushes and trees near a home provide food, a living place and sheltered passage for pests such as rats, mice, bats, birds, roaches and ants.

Seal utility openings and joints between materials. Use corrosion-proof materials such as copper or stainless steel mesh.  Rodents can chew through many materials and squeeze through tiny openings.

Reducing Food and Water

Provide places to store food that are dry and ventilated. Provide a place to store trash and to facilitate recycling.

Design and construct the home to be dry and to dry if and when it gets wet. Do not install carpet in areas prone to get wet: bathrooms, laundry rooms, kitchens, entryways and basements.

In the Northeast, dust mites do not generally colonize buildings because buildings are too dry formuch of the year. They colonize bedding, stuffed animals and favorite chairs because we humidify these things with our bodies. Control is by washing these items in hot water (greater than 130° F), which kills the mites and washes away allergens.

Pesticides

In the design and construction of new buildings, pesticides have a very limited and targeted role to play. In a neighborhood infested with a difficult species like roaches or termites, use a limitedamount of low toxicity pesticide in targeted locations. In high-risk termite areas, exclusion and inspection detailing — plus a combination of treated wooden materials and soil treatment — is useful. For roaches, dusting with boric acid in areas that would be hard to treat later is an effective, low risk strategy. For example, dust with boric acid inside the kick space beneath sink, then seal the kick space as completely as possible.

To assess risk factors associated with a pesticide, look at:

• Registration, classification, use and mode of action
• Specificity, effectiveness and repellency
• Toxicity to humans
• Cautions on label
• Toxicity in the environment
• Resistant populations

Look especially for products like insect growth hormone regulators, which are species-specific, effective and have low toxicity for the applicators, occupants and the environment.

Don’t spray pesticides; apply them directly to surfaces to be treated.