Blown-In Insulation in Richmond, VA

Blown-in insulation is loose fiberglass or cellulose fed through a hose by a machine. It covers joists, fills around wiring and blocking, and builds up to a uniform depth, which batts struggle to do in a cluttered attic. For a typical vented attic floor in Richmond, it is usually the least expensive way to reach the R-49 to R-60 range the Department of Energy recommends for this climate zone.

Fiberglass or cellulose

Both work, and the differences are practical:

• Fiberglass: about R-2.2 to R-2.9 per inch according to HomeGuide, so it takes more depth. It does not absorb much water and does not settle as much. It is light, which matters over older plaster ceilings.
• Cellulose: about R-3.1 to R-3.8 per inch. It is made largely from recycled paper treated with fire retardant, is denser and does a better job of slowing air movement through the insulation itself. It settles more over time, so it is installed a little deeper to allow for that.

We will recommend one for your attic and tell you why, but either is a sound choice when it is installed to the right depth.

Depth matters more than the label

The Department of Energy notes that loose-fill R-value does not rise in direct proportion to thickness, because the material compresses under its own weight. Each product has a coverage chart that lists the installed depth, settled depth and number of bags needed per square foot for each R-value. We work from that chart, count bags, and leave depth rulers in the attic so you can see the result.

Seal first, then blow

Blown-in insulation slows heat but lets air pass. In an attic floor full of open top plates, wire holes and light housings, warm humid summer air and conditioned house air keep moving through it. We seal those gaps before insulating, set baffles at the eaves to keep soffit vents open, and keep insulation away from flues and fixtures that need clearance.

In closed walls

Blown insulation also goes into existing walls through small holes, either from inside or from outside under the siding. That is covered on our wall insulation page, but the material is the same: dense-packed cellulose or fiberglass at a higher density than attic loose fill so it does not settle and leave a gap at the top.

When blown-in is not the answer

If the attic holds ducts or an air handler, a wet or contaminated layer of old insulation, or rooms with sloped ceilings, blown-in on the floor may not be the best fit. We will tell you when spray foam or removal should come first.