Insulating Attic Joists

If you decide on mineral wool such as glass wool or rock wool you will need to put down a damp proof membrane.

Insulating attic joists.

In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below. When unrolled batting assumes its loft or thickness. Although it s common to talk about installing insulation on the attic floor most attics don t really have a floor. In practical terms you can choose between mineral wool or insulation boards.

Overlap the seams by about 12 inches and run the plastic up the walls at least 6 inches. If your insulation is just level with or below your floor joists i e you can easily see your joists you should add more. Fill the entire depth of the joists with insulation. In an unfinishedattic the most effective method is to add insulation between the joists of the attic floor.

Standard joist spacing for the installation of attic flooring materials is 16 inches on center oc meaning the distance from the center of one joist to the center of the next joist is 16 inches. So insulating the floor of the attic is not only the best solution but it is also the simplest and cheapest. Either batting or blown insulation works in attics. Batting comes in rolls and is sized to fit between rafters or joists.

Spread plastic sheeting over the crawlspace floor to block ground moisture from entering the area. Add new insulation if your attic has no insulation install either foil or kraft paper faced fiberglass rolls or batts in between all the attic floor joists which are also the ceiling joists of the rooms below. 1a attic access door. Check the insulation manufacturer s instructions for the necessary thickness of plastic.

No matter what kind of insulation you currently have in your attic one quick way to determine if you need more is to look across the span of your attic. Always cover the tops of the ceiling joists to make sure the insulation is deep enough to reach your target r value and. You can lay fiberglass sold in pre cut batts or rolls that you cut to size into the joist cavities or pour in loose fill insulation cellulose is the most common type although you can occasionally find glass fiber and rock wool.