Spray Foam Insulation in Davenport, IA

Spray foam insulation goes on as a liquid, expands into every crack and cures in place, so it insulates and seals air in a single pass. In Davenport, where Wikipedia's climate section lists an average of about 30.7 inches of snow a year and a record low of -29F, that seal matters as much as the R-value. Foam does its best work where cold air and moisture meet the house: rim joists, basement walls, kneewalls, cathedral ceilings and steel buildings. We spray two kinds, and picking between them is the first decision on every job.

Closed cell vs open cell

Closed-cell foam cures hard and dense. HomeGuide rates it at R-5 to R-7 per inch, and at typical thickness it slows water vapor and does not absorb water. It also stiffens the surface it is sprayed on. Open-cell foam is softer and expands much more, at R-3.5 to R-3.7 per inch. It seals air well and quiets sound, but vapor can pass through it, so in Climate Zone 5 it needs a vapor retarder on the warm side or an assembly that can dry.

In the Quad Cities, that steers closed-cell toward the cold, damp places: rim joists, foundation walls, crawl spaces, roof decks over vaulted ceilings and the steel in shops and pole barns. Open-cell fits interior walls, floors between heated rooms, and some attic rooflines where moisture is handled.

Thickness and the code target

Iowa's residential code table lists R-20, or R-13 plus R-5 continuous, for wood-frame walls in Zone 5 and R-49 for ceilings. Closed-cell foam reaches high R-values in a few inches, which matters in a 2x4 wall or a shallow roof bay. In a roof with no attic, it is hard to reach a high R-value with batts and still leave a vent channel, and that is a common reason to use closed-cell against the deck. We size the thickness to the target and write both numbers on the quote.

The rim joist: our most common foam job

The rim joist is the band of wood that sits on top of the foundation and carries the floor framing. In most Quad Cities basements it is bare wood or has a little fiberglass stuffed against it, and it leaks cold air all the way around the house. Two to three inches of closed-cell foam seals and insulates it in one step. If you are finishing a basement, this is the time to do it, before framing and drywall go up.

Older houses

Davenport's pre-war houses, and the ones across the river in Moline and Rock Island, often have open cavities that run between floors and act like chimneys for warm air. Foam is a practical way to close those at the top and bottom. We also foam kneewalls and the attic floor behind them in story-and-a-half homes, cantilevered floors and the floors of rooms over garages.

When foam is the wrong call

Foam does not fix a leak. If a roof, window or plumbing leak is wetting the framing, it has to be repaired first or the foam will hide the damage. Foam should not go over knob-and-tube wiring or vermiculite that may contain asbestos until those are dealt with. And on a wide-open attic floor, sealing the gaps and blowing loose fill on top usually costs less. We tell you which parts of the house are worth foaming and which are not.

Curing and getting back in

We cover floors and belongings, mask windows and outlets, and set up ventilation before we spray. HomeGuide advises staying out for 24 hours or more while foam cures. Foam also needs the surface and the material within a working temperature range, so for cold attics and unheated buildings in winter we add heat or wait for a better day. Once cured, foam does not settle or sag. Get a free estimate