Compressing Attic Insulation

Grab a tape measure and a flashlight to see what kind of insulation you already have in the attic and how deep it is.

Compressing attic insulation.

Then use the numbers in the chart at right to estimate its r value. An example would be compressing r 19 insulation typically 6 thick into a 2x4 stud cavity that is 3 deep. The chart below indicates the compressed r value of standard building insulation products when installed in framing cavities with a depth that is less than the labeled thickness of the insulation. Compressing a thicker fiberglass batt into a standard stud space reduces the insulation s r value.

Pull up and dispose of any material that s compressed water stained or moldy it s useless. Open insulation packages carefully and only as you need them. In most communities local lumberyards stock fiberglass insulation that meets local building codes. The north american insulation manufacturers association naima has a little two page document about compressing fiberglass insulation pdf.

If you live in an area where frozen pipes are a concern make sure the insulation protects the pipes from cold air. 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. When compressed to less than its labeled thickness glass fi ber insulation will experience a reduction in r value. 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.

Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. Compressing the material changes the r value. 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. The facts about compressing fiber glass insulation q.

Here s what they say. 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.