Home Ventilation Help!

Ventilation

During the past few years, many homeowners have become increasingly aware of the energy savings afforded by properly venting their attics. On hot summer days, the temperature inside an attic can reach well over 120 degrees, putting additional strain on the cooling system. In the winter, the energy loss can result in colder rooms and/ or higher heating bills.

The use of soffit vents and ridge vents to ventilate the attic has been well advertised. In addition to the energy savings, a properly ventilated attic can also help protect your paint. Without proper ventilation, hot moist air can be trapped inside an attic. Moisture build up in fascia boards, soffits, and siding can contribute to mildew growth. In addition, the moisture accumulation can force paint off of a wood surface as it attempts to escape.

Exterior sources of moisture (e.g. rain or sprinklers) can be controlled by caulking, painting or otherwise sealing exposed areas (It is important to regularly inspect all caulk for signs of failure.) Controlling exterior sources of moisture is crucial for preventing wood rot, premature paint failure and other damage. Interior sources are much more difficult to control and are potentially much more damaging. Moisture generated within the home-from cooking, bathing, washing, etc.--must be provided a path to escape. (It is estimated that the average family of four generates 2.5 gallons of water vapor everyday.)

Such moisture will seek the path of least resistance. If venting is insufficient, the moisture will migrate through walls and ceilings. As the moisture reaches the exterior of the house, it can become trapped between the paint film and the substrate, resulting in premature paint failure.

As the moisture reaches the surface of the wood, it can force the paint film away from its substrate, resulting in bubbling, cracking and peeling. This is most apparent on soffits, fascia, and siding.

Passive systems, such as those utilizing soffit and ridge vents, are the most common and energy-efficient. Such systems rely on air pressure to draw cooler air through the soffit vent as warmer air rises and escapes through the ridge vent.

Experts recommend approximately 1 square inch of venting per square foot of attic floor space. This venting should be evenly divided between intake and exhaust.

Older homes frequently have insufficient venting. A variety of soffit vents can be easily installed in most homes, and can reduce both energy consumption and maintenance expenses. While adequate ventilation is most often discussed in relation to its beneficial effects on roofing materials and energy costs, proper ventilation can also help extend the life of paint.

Types of Vents

Soffit vents-- These are placed in the soffit (overhang). They can be continuous, or consist of round or rectangular vents.

Ridge vents-- These are placed at the peak(s) of the roof.

Powered vents-- These are installed near the peak of the roof and are driven by electrical power.

Turbines-- These are installed near the roof peak. Wind causes the turbine to spin, creating a negative pressure which draws air out of the attic.

Gable louvers-- These are usually installed in the upper areas of gables. They allow cross ventilation of the attic and roof decking.

Drip edge vents-- These are installed at the edge of the roof. They are used in situations that prevent installing adequate soffit vents.