As you plan your insulation project, keep in mind that it's also important to use vapor barriers and ventilation to maintain a healthy balance of air and moisture movement throughout your home.
Vapor barriers
During cold weather, water vapor from the warm inside air travels through unsealed holes and cracks, and condenses on cooler surfaces, including exterior walls, the underside of the roof and within insulation.
This condensation can rot wood framing, blister paint, ruin insulation and damage the roof. Vapor barriers installed between insulation and interior surfaces can help prevent this problem.
You can purchase batt or blanket insulation with an attached vapor barrier, usually made of coated kraft paper or foil-backed paper.
When using unfaced batts or blankets, or loose-fill or foam insulation, you can add four- or six-mil thick polyethylene sheeting.
If you're installing insulation yourself, remember these guidelines when using a vapor barrier: - Always place the vapor barrier towards the warm side of the insulated area - facing downward on the attic floor or to the interior side of the wall.
- When adding a second layer of insulation to an attic, do NOT add a second vapor barrier - this can trap moisture inside the first layer. Use loose-fill or unfaced batts or blankets; if only faced batts are available, cut facing every few inches to allow air to pass through.
- If the vapor barrier tears during installation, tape it tightly.
- If you have a crawlspace, add polyethylene vapor barrier on the floor of the area to reduce condensation from ground moisture.
Ventilation
It may seem like attic vents defeat the purpose of insulation, but they're a vital part of keeping fresh air circulating through your home.
An unventilated attic can trap heat during the summer, raising the indoor temperature by several degrees and putting a strain on your air conditioner. During the winter, warmer air trapped in the attic can cause ice dams than can lead to serious roof damage.
Attic vents can be positioned in several ways. New homes built in the Midwest usually have a combination of continuous ridge and soffit vents.
Never cover attic vents with insulation. If your home has no attic vents, be sure to add several before installing new or additional insulation - your contractor or retailer can advise you on what's best for your situation.
For the best indoor air quality – and even greater energy savings – you can invest in a heat recovery ventilator. This device will provide continuous circulation to ensure your home has healthy air. |
