Blown-In Insulation Hamilton

Settling Is Normal and It Is Priced In or It Is Not

Loose-fill material compacts over time. Cellulose settles more than blown fiberglass, which is why it is installed above the target depth rather than level with it, so that the settled depth is the rated depth. A contractor who fills to the finished number on day one is selling an attic that will be under specification within a couple of seasons. It is also why an attic insulated years ago can measure short today without anyone having done anything wrong at the time.

Air Sealing Comes First, Every Time

Blown-in material sits on the ceiling plane and does nothing to stop air passing through it. If the ceiling below leaks at pot lights, top plates, plumbing penetrations and the attic hatch, conditioned air moves straight through the fibres regardless of depth. Sealing those paths before the material goes down is what makes the depth meaningful, and it is the step most often skipped.

Cellulose or Blown Fiberglass Here

Cellulose is denser, made largely from recycled paper, treated for fire resistance, and resists air movement better. It also absorbs and holds water more readily, which matters in a lake-effect climate if there is any history of a roof leak. Blown fiberglass is lighter, handles damp with less risk, and adds almost no load to an old plaster ceiling — which is a real consideration in century housing.

When Blown-In Is the Wrong Answer

If the attic is partly finished or used for storage, a floor fill gets compressed and stops working. If ductwork runs up there, material on the floor leaves that equipment in unconditioned space. If the existing material is damp or contaminated, nothing should go on top of it until it has come out. We will say so in each case rather than quoting the easier job.