Improving Attic Ventilation Without Soffits

The open area of a vent is sometimes listed on the roof air vent as nfva net free vent area.

Improving attic ventilation without soffits.

If not measure the size yourself. With old homes it can be very difficult to properly ventilate the attic for a variety of reasons. The building code lets you reduce that by half under some conditions but more roof ventilation is usually better. This creates a natural air flow by drawing in the air from outside pushing it up and out through the vent at the top of the house.

Roof eave venting on roofs with no overhang or soffit how to correct improper or inadequate attic or under roof ventilation in buildings detecting and correcting attic condensation and preventing ice dam leaks in buildings how to correct improper or inadequate attic or under roof ventilation in buildings. Screw holes through both flanges. Next lay the strip vent down on a flat wood surface such as a plywood sheet or long 2 x 4 and drill 1 8 in dia. Roof vents will provide about half of the vent area and soffit vents the other half.

One common problem is caused by ice buildup along the edges of a roof. If i had an older home without soffits i would strongly consider just completely air sealing the attic and adding foam insulation totally removing the need for ventilation. The use of vented soffits along with non vented soffits helps prevent ice dams from forming along your roofline. Even without soffit venting it is important to provide an air gap at the soffit level to help keep the roof deck dry.

These ice dams form when warm attic air melts the snow on the roof and the water refreezes along the colder edge of the roof. Space the holes 12 to 14 in. The most common way to add ventilation to an attic is by installing air intakes in the soffits and putting an outlet at the gable of the house. Without proper airflow warm air can be trapped within the attic and cause ice dams to form along the roof line as snow and ice on the roof is melted from the warm air and then refreezes on the colder roof edge.

Step 5 attach the vent to the soffit photo by merle henkenius. With the help of an assistant raise the vent up to the soffit and center it over the cutout slot. Attic ventilation fans are a type of attic fan that cools attics by pushing hot air outside while pulling in cooler air from soffit and gable vents. For more information on ventilation and moisture control read this article i wrote on proper attic ventilation it s my position that you should have a proper ventilation system in your attic and that you should always take the time to air seal the floor of the attic.

The total venting space should equal 1 150 of the floor. Authoritative expert building diagnostic and repair advice toxic black mold and.