Does An Attic Need A Co

Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator.

Does an attic need a co.

Ideally there should also be plenty of soffit intake space their calculations recommend 336 net square inches of open soffit. In particularly cold climates you might go up to r 60. Your attic may presently have a fixed ladder a pull down ladder or no ladder at all. There are many types to choose from including blown in cellulose batt such as fiberglass mineral wool or cotton.

After confirming that your attic is air sealed you need to select insulation. However many building code officials have accepted unvented attics on a case by case basis when presented with compelling evidence such as hygrothermal modeling of proposed assemblies that the assembly will function properly. Ft of attic space for example 20 x 50 to be effective. Calculate or enter the square footage of the attic or area to be vented.

Your home s r value score will guide you toward the type of insulation you need. According to the home ventilating institute hvi powered attic ventilators need to move a minimum of 700 cubic feet per minute cfm for 1 000 sq. Whole house fans need windows and doors open and attic fans need lots of soffit vents to suck cooler outdoor air up into the hot attic. In other words the entire vent opening doesn t count as vented space.

Without this open space the fans will not move much air. That said air resistance and interference such as vent grates reduces the area of true ventilation. What your attic probably does not have is a set of code compliant stairs. To convert your attic to living space you cannot provide access via a ladder.

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. Ibc requires ventilation in attics and crawl spaces and does not address the unvented attic concept.