Choosing the right insulation is one of the smartest, most cost-effective upgrades you can make to a New York or New Jersey home, often trimming energy bills by 20% or more. Below we compare the three most common options — spray foam, fiberglass, and cellulose — with honest building-science facts so you can decide what truly fits your home and your budget.
Start With R-Value and Our Climate
R-value measures how well a material resists heat flow — the higher the number, the better the insulating power per inch. Westchester, Rockland, and Bergen County all sit in a cold-winter climate zone, so the U.S. Department of Energy recommends roughly R-49 to R-60 for attics here. Walls, floors, and crawl spaces have their own targets. Two things matter just as much as R-value, though: air sealing (stopping the drafts that carry heat out of your home) and correct installation. The best material installed poorly will underperform a modest material installed well.
The Three Main Types Compared
Spray Foam
Spray foam expands to fill gaps and seals air leaks as it insulates, which is why it delivers the highest performance per inch. It comes in two forms:
- Closed-cell: about R-6 to R-7 per inch, and it acts as both an air barrier and a vapor barrier. It is rigid, adds structural strength, and resists moisture — ideal for rim joists, crawl spaces, and tight cavities.
- Open-cell: about R-3.5 to R-3.8 per inch, softer and more affordable, excellent at air sealing and dampening sound, best kept to interior applications where moisture is not a concern.
Fiberglass
Fiberglass is the familiar option, available as pre-cut batts or blown-in loose fill:
- Batts: about R-3 to R-4 per inch, budget-friendly and well suited to open, standard-framed walls and attics.
- Blown-in: fills irregular spaces and tops up attic floors evenly.
Fiberglass does not stop air movement on its own, so pairing it with dedicated air sealing is important to reach its rated performance.
Cellulose
Cellulose is made largely from recycled paper treated for fire and pest resistance, blown in as loose fill at roughly R-3.2 to R-3.8 per inch. Its density lets it pack tightly around wires, pipes, and framing, which helps slow air movement better than loose fiberglass. It is a strong, eco-friendly choice for attics and existing wall cavities.
One more option worth knowing: mineral wool (about R-3 to R-4.2 per inch) is fire-resistant, water-repellent, and excellent for soundproofing.
What Actually Drives the Cost
We never quote a real project by the square foot sight unseen, because honest pricing depends on your specific home. The biggest cost factors are:
- Material type: closed-cell spray foam costs more per inch than fiberglass or cellulose, but reaches your R-value target in less thickness.
- Square footage and thickness: how much area you are covering and the R-value you are aiming for.
- Accessibility: an open attic is straightforward; finished walls, tight crawl spaces, and hard-to-reach cavities take more labor.
- Removal of old insulation: wet, moldy, or rodent-damaged material has to come out first.
- Air sealing and prep: sealing gaps and adding baffles or ventilation where needed.
The only accurate number is one built around your house — which is exactly what a free estimate provides.
Rebates and Incentives
Both New York and New Jersey offer utility and state-level energy programs that can reduce the cost of insulation and weatherization for qualifying homeowners. These incentives change from year to year, and eligibility often depends on the results of a home energy assessment. Rather than chase a program name that may already be outdated, the surest path is a free energy audit — it identifies exactly what your home qualifies for right now, along with where you are losing the most energy.
Frequently Asked Questions
Which insulation is best for my attic?
It depends on the space and your goals. Many NY and NJ attics do well with blown-in cellulose or fiberglass to reach R-49 to R-60 affordably, while spray foam shines when you want to seal the attic and control moisture. An audit tells us which fits your home.
Is spray foam worth the higher price?
Often, yes — it insulates and air-seals in one step and reaches its target R-value in less thickness, which is valuable in tight spaces. In open attics, though, cellulose or fiberglass can deliver excellent results for less.
Can you add new insulation over old?
Sometimes. If the existing material is dry and in good shape, we can often top it up. If it is wet, compressed, or damaged, removal comes first — which we assess during your audit.
How much can I really save?
Many of our customers see energy savings of 20% or more, though your exact result depends on your home's current condition, the areas treated, and how well it is air-sealed.
The Home Insulators has been helping families across Westchester and Rockland County, NY and Bergen County, NJ stay comfortable and lower their bills since 2015. If you would like a clear, no-pressure recommendation built around your home, we would be glad to help with a free energy audit. Call us today at 914-233-3084 to schedule — we will show you where your home is losing energy and the smartest way to fix it.