How To Vent An Old Attic

Begin by making sure your existing system works photos 1 and 3 plugging major air leaks into the attic photo 2 and correcting any other of the common causes of poor attic venting.

How to vent an old attic.

For this reason the square footage of vent space at the base of the roof and at the peak. If you don t currently have gable vents then it would be a good idea to install this vent. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. A 30 x 40 ft.

Then aim for about 1 sq. Hot air exhaust vents located at the peak of the roof allow hot air to escape. Next bore a 3 4 or 1 in dia. That said air resistance and interference such as vent grates reduces the area of true ventilation.

Fit the vent in the hole and nail it to the soffit with. In of vent opening per 150 sq. Cut the two parallel lines with a portable circular saw. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.

It must also circulate. For proper ventilation it isn t enough for air to simply get into your attic. You can also contact your local municipality to check on building code in your area. Draw an outline for it on the soffit and cut the hole with a reciprocating saw.

Most building codes require a ratio of 1 150 ventilation space to attic floor space. If those steps don t solve the problem add more soffit vents following the techniques we show in photos 4 17. The building code lets you reduce that by half under some conditions but more roof ventilation is usually better. The idea is that wind goes into one gable vent and then pushes the air out of the attic and through the secondary gable vent on the other side of the attic.

Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation. In other words the entire vent opening doesn t count as vented space. Attic for example has an area of 1 200 sq. First determine your attic area by multiplying the length by the width.