Spray Foam Insulation in Asheville, NC

Spray foam insulation goes on as a liquid, expands into gaps and cures in place, so a single layer both insulates and stops air. In Asheville homes that matters in two seasons: winter, when heated air escapes through the attic and pulls cold air in at the crawl space, and summer, when humid air drifts in and condenses on cool surfaces. We spray two kinds of foam, and choosing between them is the first decision on every job.

Closed cell vs open cell

Closed-cell foam is dense and rigid once cured. HomeGuide lists it at R-5 to R-7 per inch. At typical thickness it slows water vapor and does not absorb water, and it stiffens the surface it bonds to. Open-cell foam is light and spongy, expands much further and lists at R-3.5 to R-3.7 per inch. It seals air and quiets sound, but vapor can move through it.

In a mixed-humid climate like Buncombe County's (Climate Zone 4A on OpenEI's county list), those traits point closed-cell toward places that touch the ground or stay damp: crawl space walls, rim joists, below-grade walls and the underside of roof decks with no room for vent channels. Open-cell suits interior walls, above-grade cavities and many unvented attic rooflines.

Where foam pays off in a mountain home

• Crawl space walls and rim joists. Closed-cell seals the band joist and the block walls in one pass and adds insulation where the house meets damp soil.
• Vaulted and cathedral ceilings. Ridge-lot houses often have rooms that follow the roofline with no attic above. Foam against the roof deck reaches a high R-value in a shallow rafter bay.
• Bonus rooms and kneewalls. Rooms tucked under steep roofs lose heat through short walls and the floor behind them. Foam closes the gaps that batts leave.
• Rooms over garages. Floors over unheated garages are a classic cold spot.
• Attic bypasses. Before blown-in goes on an attic floor, foam seals plumbing stacks, chimney chases and top plates.

What foam does not fix

Foam will not stop a leak, and it should never cover wet framing. Roof, window, plumbing and drainage problems get fixed first. It is also not the cheapest way to insulate a big open attic floor; sealing the leaks and blowing in cellulose or fiberglass usually costs less. If we see old knob-and-tube wiring or vermiculite that could hold asbestos, we stop and tell you before any foam is quoted.

Prep, curing and re-entry

Spraying is fast; prep takes longer. We cover floors and furnishings, mask openings, and set up ventilation. HomeGuide advises staying out of the house for at least 24 hours while foam cures, so plan a day away for interior work. Crawl space and garage jobs often affect the living space less, but we will talk through it for your house.