Start with the job, not the company
Before you call anyone, write down what you want insulated (attic roof deck, attic floor, walls, crawl space, rim joists, a metal shop or barn) and what problem you are trying to solve: a hot upstairs, high cooling bills, condensation on metal, or noise. A good installer will ask about all of this; a weak one will just ask for the square footage.
Princeton is in Collin County, which the energy code places in climate zone 3A (warm and humid). Here the long cooling season and attic ductwork usually drive the design, so the right contractor should talk about where the air barrier goes, what happens to the attic vents and how your HVAC equipment fits into the plan.
Open-cell vs. closed-cell foam at a glance
Most Princeton homes use one or both. Ask each contractor which they recommend for each area and why.
| Open-cell foam | Closed-cell foam | |
|---|---|---|
| Density and feel | Soft, light and spongy | Rigid and dense |
| Insulation per inch | Lower, so it is sprayed thicker | Higher, so thinner layers reach the target |
| Moisture | Lets water vapor pass; not for areas that get wet | Acts as a vapor retarder and resists water |
| Typical Princeton uses | Attic roof decks, interior walls, sound control | Metal buildings, crawl spaces, rim joists, exterior walls |
| Relative price | Usually the more budget-friendly choice | Usually costs more for the same area |
Pricing depends on your home, so we never post one-size-fits-all numbers. Ask for a free quote that lists foam type, thickness and area.
Code and safety items Princeton homeowners should ask about
Fire protection: under the International Residential Code (section R316), foam plastic insulation generally has to be separated from living space by an approved thermal barrier such as half-inch drywall. In attics and crawl spaces that are entered only for service, the code allows an ignition barrier or a specifically tested assembly instead. Ask which approach the contractor will use in your attic and ask for the product's evaluation report showing it is approved for that use.
Re-entry time: the U.S. EPA advises that occupants and other trades leave the home during spraying and not return until the foam has cured and the space has been ventilated and cleaned. Re-entry time depends on the product, so ask the contractor for the manufacturer's guidance for your exact product before you book a date.
Permits and HOAs: insulation work tied to a remodel, an addition or HVAC changes can involve a permit, and some Princeton neighborhoods have HOA rules for exterior work and contractor access. Ask who pulls any permit and who schedules inspections, and get that in writing.
Questions to ask every spray foam contractor
- Which foam (brand and product) will you use in each area, and how thick will it be?
- What R-value will I have when you are done, and how will you show me the thickness?
- Will the attic be vented or unvented afterward, and what happens to the existing vents?
- Which thermal or ignition barrier does my attic need, and is it included?
- How long must my family and pets stay out, and what ventilation will you run?
- Is removing old insulation and debris included, or is it a separate line item?
- Can you show proof of general liability insurance and workers' compensation coverage?
- Who on the crew is trained on this product, and who supervises the job?
- What warranty covers the work, and what does the manufacturer warrant?
Red flags
- A quote that does not name the foam type, thickness or area, or that is only a single lump sum.
- No mention of a thermal or ignition barrier, or a claim that "foam never needs one."
- No plan for ventilation and re-entry, or pressure to stay home during spraying.
- A guaranteed amount of savings on your energy bills, which no installer can promise.
- Pressure to sign the same day, or a large payment demanded before materials arrive.
- Reluctance to provide proof of insurance or references from nearby jobs.
Get your free, exact quote
We don't post prices because every project is different. Tell us about yours and a local pro will give you an exact number, free and with no obligation.
Get my free, exact quote Or call (469) 812-8909
Sources checked 2026-10-30: EPA: vacate and safe re-entry time for spray polyurethane foam; American Chemistry Council: Know the Code, spray foam in attics and crawl spaces; IRC Table N1101.7 climate zones by county (UpCodes).