The attic can be a junkyard that may just contain a painting by Andrew Wyeth beneath all the junk. The attic can be a game room where you don’t have to listen to your kids talking about Zelda, Pikachu or Lara Croft. The attic can be a home office that keeps your work and domestic situations separate but equal. The Perfectly Cromulent Guide to Habitable Attics attempts to let you in on some of the most important information you need to know about habitable attics.
The window area in a habitable attic must be sized so that it is at least 8% of the floor area. Half the glazed area of glazed windows must be openable unless mechanical ventilation is supplied. Those using their habitable attics for sleeping need to have at least one exterior door or a window through which escape is humanly possible. There must be at least 70 square feet of living space with a horizontal dimension of at least seven feet. All attics except those converted into a kitchen must have a ceiling height of at least 7.5 feet covering half the total area.
Insulating a habitable attic is trickier than insulating a non-habitable attic. Attics with a floor will usually be served best with loose-fill insulation that is blown in. Another way to go is to remove the floor before habitation takes place and use standard insulation batts. Loose fill insulation gives you the choice between cellulose and fiberglass. Fiberglass will settle over time and that can significantly decrease the efficiency of your insulation. On the other hand, you must make sure that moisture is kept away from cellulose insulation or otherwise you’ll have a goop on your hands and feet and knees and bottom.
A vapor barrier condenses and collects moisture in the air when warm moist air goes up for battle against cold air from the outdoors. Don’t think you can double your protection by using two vapor barriers; condensation will merely be trapped between the two water vapor barriers in your habitable attic.
Forget about using pull-down stairs or a trap door for access into habitable attics. You must provide a stairway that is between 2 and 6 feet wide between two handrails or one handrail and the wall. Look to making use of a closet space for installation of a stairway and keep in mind that circular staircases make the smallest footprint, but can be heck to deal with when lugging a mattress, work desk or large screen TV up to your habitable attic.
Radiant barriers are a layer of aluminum foil utilized to block radiant heat transfer from the hot roof to the insulation in the attic. Under the sheathing method is the simplest and most affordable means of achieving this if you are building a new home. Attaching the foil to bottom edges of the rafters is the easiest method for existing homes because you can merely staple the material to the bottom side of rafters.
The cubic-foot-per-minute (CFM) rating of your habitable attic can be calculated by multiplying the attic’s square footage by .08. Knowing the CFM rating will guide you in picking an attic fan. The best place to install an attic fan is in a gable-ended wall or the roof. Keep in mind that a darker color roof means getting a bigger fan because of the heat that is absorbed.
Encyclopedia of Home Improvement by Michael W. Litchfield
The Visual Handbook of Building and Remodeling by Charlie Wing
Creative Homeowner Guide to Home Repair and Improvement
Home Improvement 1-2-3 by the editors at Lowe’s.
Ortho’s Home Improvement Encyclopedia