Do You Need To Vent An Attic With Exterior Insulation

Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall.

Do you need to vent an attic with exterior insulation.

When the attic becomes part of the home to be heated and cooled open wall gable vents and roof vents are no longer feasible but the underside of the roof the sheathing and rafters can still get. Complete coverage of the attic floor along with sealing air leaks will ensure you get the best performance from your insulation. If the atmospheric combustion appliances start off in a vented attic the building code doesn t require those vents because the appliances are already connected to the outside and should get plenty of air. The traditional remedy to this wetting is to slow the influx of moisture laden air into the cavity by using an interior vapor retarder and by ventilating the roof cavity to the exterior in order to facilitate the carry off of moisture i e.

Install low gable vents located above the top level of the attic ceiling insulation. Insulation is used in an attic for cross ventilation to minimize potential for moisture accumulation and condensation to help energy savings and moisture control. Whether the home is old or new however anyone considering spray foam insulation would be wise to ask this question. Focus on the other ventilation you have in the attic.

Use eye brow vents that are on the top of the sloping roof surface near the soffit eave area. Your attic should have a certain amount of insulation in it and the recommended level of insulation for your attic is dependent on where you live. Correct that mistake so that humid exhaust air doesn t get trapped in your insulation and ruin it. Traditionally insulation materials that are placed inside of an attic will require air circulation within the attic space to assist in drying excess moisture in this indoor space.

On the other the florida solar energy center university of central florida found that attics with nominal natural ventilation and r 19 ceiling insulation do not need powered vent fans as it turns out because the insulation slows heat from moving down into the living space homes with well insulated attics don t see a significant. Direct all exhaust fans and vents to the exterior. Though it s against building code to vent any kind of exhaust to an attic space many home builders have gotten away with this shortcut. To completely cover your attic floor with insulation out to the eaves you need to install rafter vents also called insulation baffles.

First things first you need to go up into your attic inspect the condition of the insulation and calculate the current level of insulation. If you are installing a new roof consider a drip edge vent. 1 300 ventilation ratio recommended.