Blown in Cellulose insulation settles and as it settles the “R” value changes. Cellulose insulation manufacturers measure the “R” value on settled material. If you have 15” of cellulose blown, the “R” value needs to be measured, not for the 15”, but the settled total which may be only 10 or 12”. Moisture degrades the insulating value of Cellulose and can cause the cellulose to compact more. Also In order to have the maximum insulating value, the paper is ground up into a very fine powder that can easily float around the air. This powder, containing residues from the original papermaking process, the different inks used each time it was recycled and the added chemical compounds, is easily inhaled.

Only Spray Polyurethane Foam does not change.

  • SPF does not settle, its rigidity actually adds to the strength of the building
  • SPF “R” value remains constant for the life of the building
  • SPF blocks air infiltration — a leading cause of heat/cooling loss
  • SPF is inert, it does not add dust or chemicals into the air

Source: Green Insulation Technologies

Foam insulation—perfect for Michigan's weather