Frequently Asked Questions

HomeGuide's national range is $1.50 to $5.00 per square foot installed, with attics at $3,000 to $8,000 and rim joists at $2,000 to $2,500. Access, foam type, thickness and any removal change the total. We give you a written price after seeing the space, and that is the price.

The 2025 NYC Energy Conservation Code places the city in Climate Zone 4A and lists R-49 for ceilings. That applies to new work and renovations covered by the code. For an existing attic, it is a sensible target, and we write the planned R-value on the quote.

No spray foam is fireproof. Foam plastic insulation generally has to be separated from living space by a thermal barrier such as drywall, and in some attics and crawl spaces an ignition barrier coating is used instead. We plan the covering with the foam so the finished job meets code for that space.

Closed-cell foam, at R-5 to R-7 per inch according to HomeGuide, compared with R-3.5 to R-3.7 for open-cell. That is why closed-cell is used where space is tight, such as rim joists and shallow rafters. Open-cell can still reach the target R-value where the cavity is deep enough.

Often yes, once the space is dry and any damaged material is gone. Closed-cell foam absorbs very little water, but below the base flood elevation in a mapped flood zone, FEMA's rules limit which materials are acceptable. We check your situation before recommending anything.

It costs more per square foot than blown-in, it needs the household out of the space while it cures, and it is hard to remove later. It also hides whatever it covers, so leaks and wiring problems have to be dealt with first. Where loose fill does the job for less, we say so.

Yes. We work across Staten Island, North Shore, Mid-Island, East Shore and South Shore. Call (646) 461-2857 and tell us your neighborhood.

For rim joists, basement and crawl space walls, damp or flood-prone areas and shallow roof rafters, usually yes, because it holds more R-value per inch and slows vapor. In interior walls and deep above-grade cavities, open-cell often does the job for less. Where both could work, we price both.

Foam under the roof deck hides the sheathing, so a roof leak is harder to spot. It costs more than insulating the attic floor, and it brings the attic inside the conditioned space, which changes how ventilation and moisture are handled. It is worth it for cathedral ceilings or attics with ductwork, less so for a plain open attic.

HomeGuide's advice is at least 24 hours while the foam cures. For a detached garage or a crawl space sealed off from the house it may affect you less. We confirm the timing for your job.

Usually. Foam plastic generally needs a thermal barrier such as drywall between it and living space, and certain attics and crawl spaces use an ignition barrier coating instead. We include the covering in the plan.

Several national companies make spray foam systems, and installers buy them as two-part kits. What matters more for you is that the product is rated for the space and installed at the thickness written on your quote. We tell you which product we plan to use.

The NYC Energy Conservation Code lists R-49 for ceilings in Climate Zone 4A, which applies to new work and renovations. For an existing attic that is a sensible target. We write the planned R-value and depth on the quote.

The floor, in most houses, because it costs less. The roofline makes sense when the attic has ducts or equipment, is being finished, or when there is no attic above a sloped ceiling. We explain which fits your house.

Yes, along with air sealing. Most of the heat in a top floor comes from a hot attic through thin insulation and gaps. Sealing and adding depth slows that, and your air conditioner has less to fight.

Not always. Dry, clean insulation can stay under new material. Insulation that is wet, moldy, full of rodent waste or blocking the air sealing work should come out. We tell you which applies.

If the basement is heated or will be finished, insulate the walls and rim joist. If it is unheated and stays that way, insulating the ceiling can work, but pipes and ducts down there then sit in the cold. We go over both.

Sometimes. Below the base flood elevation in a mapped flood zone, only flood damage-resistant materials are allowed, and some crawl spaces must stay vented to let water pass. We check your situation before recommending anything.

No. It is not waterproofing. A leak has to be fixed from the outside or with drainage first. Closed-cell foam does keep humid indoor air off a cold wall, which stops condensation.

In most basements, yes. It is a short job, it stops drafts along the whole perimeter, and it is often the first thing we recommend below grade.

Yes. Dense-pack cellulose or injection foam goes in through small holes from outside or inside, and the holes are patched. We check wiring and blocking first.

Often, because closed-cell gets far more R-value per inch than batts and seals air at the same time. In a 2x4 wall that matters a lot. We price foam and alternatives side by side.

It helps. Dense-pack and open-cell foam both cut sound through walls and floors, though they are not a full soundproofing system.

Knob-and-tube wiring should not be buried in insulation until an electrician checks it. If we find it, we tell you before going further.

For an open attic floor, sealing the gaps and blowing in loose fill usually costs less and works well. Spray foam is better for rooflines, cathedral ceilings and tight spots. We price whichever fits, or both.

Cellulose settles slightly after install, so we blow to a depth that allows for it. Fiberglass settles less. Depth markers show what was installed.

Usually yes, if the old insulation is dry and clean. Wet, moldy or rodent-damaged insulation, or anything that looks like vermiculite, needs to be handled first.

No. Dry, clean insulation can stay and be topped up. Removal is for material that is wet, moldy, contaminated, or in the way of air sealing.

Insulation that sat in floodwater should come out, and the framing should dry before anything new goes in. Below the flood elevation, replacement materials have to be flood damage-resistant.

It should be tested for asbestos before it is touched. If it contains asbestos, a licensed abatement contractor removes it. We stop and let you know if we see it.