Blown-In Attic Insulation in Birmingham, AL

Blown-in attic insulation is loose cellulose or fiberglass blown across the attic floor with a machine. On a house where the attic holds no ducts or equipment, and the roof is in good shape, it is usually the most cost-effective way to cut heat gain through the ceiling. Many Birmingham attics we see have only a few inches of old fill, settled and patchy, or batts with gaps between them. Adding depth over a sealed attic floor fixes that for far less than foaming the roof deck.

Seal first, then blow

Loose fill slows heat, but air moves right through it. If the ceiling below is full of gaps, hot attic air and humid outdoor air leak into the house around light fixtures, plumbing stacks, the attic hatch and the tops of interior walls. So the first step is always sealing those gaps with foam, caulk and fire-rated materials. Alabama's amended code, as Alabama Power summarizes it, requires recessed lights in the thermal envelope to be sealed and rated at no more than 2.0 cfm of air leakage, and attic hatch covers to reach at least R-19. We bring older houses up to that standard as part of the job.

How deep is deep enough

Alabama's amended 2015 energy code, as Alabama Power summarizes it, calls for R-30 in ceilings for new homes. The Department of Energy recommends more for existing Zone 3 houses: R-49 to R-60 for an attic with no insulation, and R-38 to R-49 added where 3 to 4 inches are already in place. HomeGuide lists blown fiberglass at about R-2.2 to R-2.9 per inch and cellulose at about R-3.1 to R-3.8 per inch, so reaching R-38 takes roughly 10 to 17 inches depending on the material. We mark the attic with depth rulers so you can see what you paid for.

Cellulose or fiberglass

Cellulose is made mostly from recycled paper treated for fire resistance. It is dense, packs around obstructions well and has a slightly higher R-value per inch. Fiberglass is lighter, does not absorb water as readily and does not settle as much over time. Both work in a Birmingham attic. We explain the difference and let you choose, or recommend one based on your attic.

Ventilation and baffles

A vented attic needs air to flow in at the soffits and out at the ridge or roof vents. When new insulation goes in, we install baffles at the eaves so the loose fill does not block the soffit vents. We also check that bath and kitchen fans vent outdoors, not into the attic, because humid air dumped into an attic in a humid climate causes trouble.

Ducts in the attic

If ductwork runs across the attic floor, burying it in loose fill can help, but only if the ducts are sealed and insulated first, since humid attic air can condense on cold supply ducts. Where ducts and the air handler dominate the attic, we will also price attic encapsulation so you can compare.

Ask for a look at your attic, and we will measure the existing depth and write up what it would take to bring it up. Get a free estimate