Spray Foam Insulation in Reading, PA

Spray foam insulation goes on as a liquid, expands into every gap and cures in place, so one layer stops air and slows heat. In Reading, where more than half the homes are attached and much of the housing is very old, foam earns its cost in a few specific places: the shallow roof cavities of rowhomes, stone and brick foundations with wood sills on top, rim joists, kneewalls, and open walls during a renovation. In other places, like plaster walls and open attic floors, cellulose usually does as well for less.

Closed cell vs open cell

Closed-cell foam cures hard and dense. HomeGuide lists it at R-5 to R-7 per inch, and at normal thickness it slows vapor and does not soak up water. That makes it the go-to for shallow roof cavities, where every inch counts, and for foundations and sills, where cold surfaces meet damp basement air. Open-cell foam is softer and expands more, at R-3.5 to R-3.7 per inch. It seals air and quiets sound, but vapor passes through it, so in Zone 5 it needs a vapor retarder or a design that lets moisture dry.

Rowhome roofs

Many Reading rowhomes have a flat or low-slope roof with a cavity only a few inches to a foot deep between the top-floor ceiling and the roof deck. Getting a meaningful R-value into that space without trapping moisture is hard. Closed-cell foam against the underside of the roof deck reaches a useful R-value in a few inches, seals air leaks around the roof edge and cornice, and does not need a vent channel. Access is the main challenge: through the ceiling, through the roof edge, or during a roof replacement, when the deck is open from above.

Foundations and sills

Old Reading foundations are often fieldstone or brick, with a wood sill on top and gaps all around. Closed-cell foam on the sill, rim and upper wall seals and insulates in one step. We check for dampness first and leave stone that needs to dry alone.

Open walls

During a gut renovation or addition, when stud bays are open, spray foam fills them completely. Open-cell works for many above-grade walls; closed-cell adds more R-value per inch where walls are thin.

Shared walls

Party walls between rowhomes do not lose much heat to the outside, since the neighbor's house is warm too. But gaps at the top and front and back of a party wall can leak air into the roof cavity. Foam seals those gaps.

When not to use foam

Foam should not go over live knob-and-tube wiring, untested vermiculite, wet wood or a leaking roof. It is also not the cheapest way to insulate an open attic floor. We tell you which parts of your house are worth foaming.

Curing

We cover, mask and ventilate. HomeGuide advises staying out for 24 hours or more while foam cures. In a rowhome, we also think about the neighbors and keep the work area closed off. Foam needs the surface and the material within a working temperature range, so cold spaces in winter may need added heat or a milder day. Get a free estimate