Choosing insulation can feel overwhelming when every product claims to be the best. Here are honest answers to the questions we hear most from homeowners across Westchester, Rockland, and Bergen County.
What does "R-value" really mean?
R-value measures how well a material resists heat flow — the higher the number, the slower heat escapes in winter and the slower it pushes in during summer. Because R-value is rated per inch, the total performance of a wall or attic depends on both the material and how thick it is installed. Here is roughly what each common material delivers per inch:
- Closed-cell spray foam: about R-6 to R-7 per inch, and it doubles as both an air barrier and a vapor barrier.
- Open-cell spray foam: about R-3.9 to R-4.2 per inch — lighter, more affordable, and still an effective air seal.
- Fiberglass batts: about R-3 to R-4 per inch.
- Cellulose (blown-in): about R-3.2 to R-3.8 per inch.
- Mineral wool: about R-3 to R-4.2 per inch, with strong fire and sound resistance.
Which material is right for my home?
There is no single winner — the right choice depends on the space, how the assembly is built, and your goals for comfort and budget.
- Attics and open cavities are often a great fit for blown-in cellulose or fiberglass, which flow around framing and fill irregular gaps.
- Rim joists, cathedral ceilings, and tight crawlspaces frequently call for closed-cell spray foam, which packs high R-value and blocks air and moisture in a thin layer.
- Standard walls can use fiberglass batt, mineral wool, or open-cell foam, depending on your budget and how much sound control you want.
- Foundation walls and exterior sheathing often pair well with rigid board, which helps reduce thermal bridging through the framing.
Why does air sealing matter as much as R-value?
Even the thickest insulation underperforms if air leaks around it. Gaps at top plates, recessed lights, ductwork, and rim joists let conditioned air escape and pull unconditioned air back in — which is why a home can still feel drafty despite a full attic. Pairing insulation with dedicated air sealing and weatherization is usually where the biggest comfort and efficiency gains come from. Many of our customers see energy savings of 20% or more once insulation and air sealing are addressed together rather than one in isolation.
Every house is different, and the only way to know which materials will pay off most — and where — is to look at your specific home. The Home Insulators is a family-owned company that has been helping families across Westchester, Rockland, and Bergen County since 2015, and we would be glad to walk you through your options. Call us at 914-825-6824 to schedule a free energy audit — no pressure, just clear answers about what your home actually needs.