Compressing Insulation In Attic

Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces.

Compressing insulation in attic.

What happens to the r value when fiber glass building insulation is compressed into a space that is narrower than the thickness advertised on the label. Pull up and dispose of any material that s compressed water stained or moldy it s useless. When you compress fiber glass batt insulation the r value per inch goes up but the overall r value goes down because you have less inches or thickness of insulation. Rigid panels of insulation are commonly made from polystyrene or polyurethane.

Compressing a thicker fiberglass batt into a standard stud space reduces the insulation s r value. In most communities local lumberyards stock fiberglass insulation that meets local building codes. Then use the numbers in the chart at right to estimate its r value. By compressing batt insulation you will actually lose some r value.

Insulation expands once unpackaged so leave it wrapped until you are ready to use it. When compressed to less than its labeled thickness glass fi ber insulation will experience a reduction in r value. The north american insulation manufacturers association naima has a little two page document about compressing fiberglass insulation pdf. The facts about compressing fiber glass insulation q.

An example would be compressing r 19 insulation typically 6 thick into a 2x4 stud cavity that is 3 deep. If you know you aren t going to convert the attic in the future that leads you one direction compressing the insulation is fine maybe you don t care so much about head height and can add some more thickness to improve the insulation etc and if you know that an attic conversion is viable and that you are likely to want to pursue that in. Grab a tape measure and a flashlight to see what kind of insulation you already have in the attic and how deep it is. Foam board can be used on an attic hatch but wouldn t be used to insulate the entire space.

Also bear in mind that if you compress insulation in order to make it fit the product loses much of its r.