Compressing Insulation In Attic

Compressing a thicker fiberglass batt into a standard stud space reduces the insulation s r value.

Compressing insulation in attic.

Open insulation packages carefully and only as you need them. 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. Proper attic insulation is the best way to prevent heat loss in the winter and retain cool air in the summer. Commonly used for diy projects they work well in open spaces like attic floors.

Determine the type of insulation needed for your attic. Compressing insulation reduces its r value. So it s time to pay close attention to what s happening up there. Around electrical boxes notch rather than compress the batt then tuck the cutout behind the box.

The north american insulation manufacturers association naima has a little two page document about compressing fiberglass insulation pdf. We used batt insulation for our project. Compressing r 19 insulation typically 6 thick into a 2x4 stud cavity that is 3 deep. Compressing the material changes the r value.

Here s what they say. 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. To help prevent frozen pipes insulate only on the cold side. 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.

Insulation expands once unpackaged so leave it wrapped until you are ready to use it. Also bear in mind that if you compress insulation in order to make it fit the product loses much of its r. In most communities local lumberyards stock fiberglass insulation that meets local building codes.