Free Technical Information for Building Inspectors, Contractors and Consumers. Code and Manufacturer's Information Resource
Venting Your Home
Why Ventilate? More than any other part of your house, the roof is subject to extremely high heat, both on and under the roof deck. In the summer, on a clear 90°F day, the sun can heat the roof shingles to 170°F. Left unvented, heat can build up to as high as 140°F inside the attic, temperatures which can damage shingles. Eventually this uncontrolled hot air can penetrate the home's living space, warming the area below and causing increased demands on air conditioners and increased utility costs. A properly ventilated attic enables this extreme heat to escape outside. The result: Lower air conditioning costs in the Summer. In the winter, moisture from the house condenses in the attic and settles in the insulation. When wet, insulation loses its effectiveness (sometimes dropping to as little as one-third its original R-value) and allows valuable heat to escape through the attic. Even worse, soaked insulation can cultivate mold or mildew, as well as stain or crumble ceilings. A properly ventilated attic provides an exhaust system, and moisture can escape. The result: Better insulation performance and lower heating costs in the Winter. An additional danger during the winter months is the formation of ice dams. Properly vented roofs help prevent the formation of ice dams. The result: Less damage to the interior of the house and longer lasting roofs. Of all the reasons to ventilate an attic, however, the most important is to | ||
FOUNDATION VENTS: In homes with crawl spaces and dirt floors, most moisture enters the Check your foundation vents regularly to ensure they open and close What’s the Code Say? Crawl Space Vents: The under-floor space between the bottom of the floor joists The minimum net area of ventilation openings shall not be less than 1 square foot EXCEPTION # 2: The total area of ventilation openings may be reduced by 1/1500 of the The minimum net area of ventilation openings shall not be less than 1 square foot The finished grade of under-floor surface may be located at the bottom of the footings; The external wind baffle on the ridge vent causes wind to blow What’s the Code Say?
ROOF VENTILATION: Ventilation required. Enclosed attics and enclosed rafter spaces formed where ceilings separate space by ventilating openings protected against the entrance of rain or snow. Minimum area. The total net free ventilating area shall not be less than 1/150 of the area that at least 50 percent and not more than 80 percent of the required ventilating area is Vent and insulation clearance. Where eave or cornice vents are installed, insulation shall between the insulation and the roof sheathing and at the location of the vent. | ||
POWER VENTS:
If moisture is a problem in your attic, consider adding a ventilator with For safety, the motor should have an overload protection to shut the fan | ||
Power attic vents with two-speed controls WIND TURBINES: Turbines come in two sizes: 12" and 14". The latter provides almost 30 | ||
WHOLE-HOUSE FANS: There are two basic whole-house fan designs: direct-drive and belt-drive. For small to medium-size houses, a direct-drive fan is the choice. The | ||
|
