Spray Foam Insulation on Long Island

In the right spot, absolutely. In the wrong spot it is an expensive way to buy R-value you could have had for a third of the price. Foam earns its cost where you need insulation and an air barrier in the same pass and there is no depth to work with: rim joists, cathedral ceilings, the back of knee walls, overhangs, crawl space walls. On an open attic floor with plenty of headroom, blown-in gets you more R-value across more square footage for less money. We will tell you which situation your house is in, including when the answer is that you do not need foam.

Closed cell where you need the vapor control, the higher R-value per inch, or the structural stiffness: rim joists, crawl space walls, roof decks, anywhere against masonry or exposed to moisture. Open cell where you have depth to fill and want the assembly to stay vapor permeable, like interior wall cavities or a vented cathedral bay. Closed cell is roughly R-6.5 per inch against open cell's R-3.7, but it also costs meaningfully more, so filling a deep cavity with closed cell is usually money spent on performance you cannot use.

Roughly $3 to $7 per square foot installed, driven by whether it is open or closed cell and how thick it goes. That is a wide range because foam is almost always priced by board foot, meaning square footage times inches of thickness, so the depth the assembly needs matters as much as the area. We measure the assembly and quote the actual board footage rather than working off a rule of thumb.

Yes. The PSEG Long Island Home Performance program lists insulation by location, attic, wall, floor, band joist, and basement crawl space, and does not specify a material. Spray foam counts as insulation the same as blown-in against the same caps, up to $2,500 at market rate. Worth knowing though: because the rebate is a fixed dollar amount rather than a percentage, a more expensive material covers less of your total project. On a big open attic that difference is significant.

Once it is cured, yes. During installation and while curing it needs the house unoccupied and properly ventilated, and the crew works in supplied-air respirators. Cure time depends on the product and conditions, usually 24 hours before reoccupancy for most residential jobs. Any installer who tells you that you can stay in the house during a foam job is cutting a corner you do not want cut.

It can, when the wrong type goes in the wrong assembly. Open cell foam on the underside of a roof deck in our climate can let moisture through to the sheathing where it has nowhere to dry, and that is a real failure mode we have seen. This is why the assembly matters more than the product. Getting it wrong is expensive to undo, which is a good part of why we assess before specifying rather than defaulting to foam everywhere.

We assess the house, specify the assembly, run the rebate paperwork, and supervise the job. The foam itself is installed by a rig and crew who do it every day. That is deliberate. Foam is unforgiving of inexperience and we would rather put a specialist on it than learn on your rim joist.