Blown-In Insulation Chattanooga, TN

Cellulose or Blown Fiberglass?

Cellulose is denser, settles into irregular framing and resists air movement better, which suits the older attics around North Chattanooga and the historic districts. Blown fiberglass is lighter and will not add meaningful load to a weak ceiling. Both are installed over the attic floor, so both depend on the air sealing underneath them being done first.

Why Blown-In Underperforms

Three reasons, in order of how often we find them. The material was installed shallow. The attic was never air sealed, so conditioned air moves straight through the fibres. Or the depth was right on day one and the material has settled since. We measure what is actually there before quoting anything. Call (423) 799-3836 or request a written estimate below.

Settling Is Normal, and It Is Priced In Properly 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 you an attic that will be under specification within a couple of seasons. This is also why an attic insulated years ago can measure well 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 is leaking at recessed lights, top plates, plumbing penetrations and the attic hatch, conditioned air moves straight through the fibres regardless of how deep they are. Sealing those paths before the material goes down is what makes the depth meaningful. Blowing new insulation over an unsealed ceiling is the most common way money gets spent on an attic without the house changing.

Cellulose, Fiberglass and the Honest Trade-Offs

Cellulose is denser, made largely from recycled paper, treated for fire resistance, and it resists air movement better than fiberglass does. It is heavier, so a weak or damaged ceiling is a reason to think twice. Blown fiberglass is lighter, does not absorb water the way cellulose can, and handles damp conditions with less risk, but it is more easily disturbed by air movement in the attic. Neither is simply better. The attic, the ceiling structure and the moisture picture decide it.

When Blown-In Is the Wrong Answer

If ductwork or an air handler sits in the attic, material on the floor leaves that equipment in unconditioned space and foam at the roof line is usually the better spend. If the attic is partly finished or used for storage, a floor fill gets compressed and stops working. If the existing material is damp, contaminated or rodent-damaged, nothing should go on top of it until it has been removed. We will say so in each of those cases rather than quoting the easier job.