Doors and Windows
Windows are among the most complex building components in a house. In addition to the important architectural contribution they make, windows have far-reaching energy consequences. Their number, total area, and orientation to the sun will affect the home’s lighting/ventilation and consequently determine the natural temperature of the house.
Low-e glazing. A low-e coating is a thin, nearly invisible metallic coating on glass that lowers the emissivity of the glass. The effect of the coating is to lower the window’s U-factor, improving its performance as a thermal insulator. Low-e windows make sense in every U.S. climate, and the cost of upgrading a window to low-e glazing is a cost-effective, energy-saving investment.
The one thing that inspectors never fail to check is the required emergency-egress window from a sleeping room. At least one window in each bedroom must be of sufficient size to permit the occupants to escape a fire and also to allow a fully outfitted firefighter to enter.
An egress window must have an opening that will satisfy all four International Residential Code (IRC) criteria:
- 1. Minimum width of opening: 20 inches
- 2. Minimum height of opening: 24 inches
- 3. Minimum net clear opening: 5.7 square feet (5.0 square feet for ground floor).
- 4. Maximum sill height above floor: 44 inches
Even the most energy-efficient windows and doors must be installed properly, by professionals, and according to manufacturing recommendations.
Improper installation will reduce energy performance and create energy leaks that result in higher energy bills, and may even cause moisture damage to structure, interior applications such as drywall and flooring, as well as damage to insulation materials and finally deterioration of exterior applications such as stucco or sidings.
The following additional guidelines should help the homeowner in the process of selecting a knowledgeable and experienced installer as well as to verify proper installation during the project.
By any means, it is not a recipe for a DIY installation for an inexperienced individual.
1. The rough opening in the framing should be 1/4-inch to 1/2 inch larger each way then the actual size of the window. This gap will allow perfect leveling of the window inside the wood frame (that is not always possible to level), and also allow for wood expansion in the summer.
2. Use weather resistive paper recommended by the manufacturer around the opening. The paper should be thoroughly glued to the surface rather than stapled.
3. Use type and amount of screws recommended by the manufacturer to fasten the window to the wall. Many manufacturers recommend zinc screws and do not allow screws in the corners of the windows.
4. To perform correctly, windows must also be properly air sealed during installation. To air seal the window, caulk the backsides of the window mounting flanges (top and sides only) to the weather-resistive barrier during installation. The mounting flange (nailing fin) is an integral part of most window frames that laps over the conventional stud construction. Nails are driven through it to secure the frame in place. Also, from inside the house, seal the gap between the window frame and rough opening using backer rod and caulk or non-expanding latex-based spray foams that will not pinch jambs or void window warranties. Backer rod is a closed-cell foam or rope caulk that is pressed into cracks or gaps with a screwdriver or putty knife. Insulation stuffed into this crack does not stop air flow.