Your attic is where most homes lose the most energy, so choosing the right insulation up there is one of the smartest comfort and cost decisions you can make. The best choice depends on how your attic is built, your goals for comfort, and how each material handles both heat and air movement.
Start With R-Value — and Air Sealing
Insulation is rated by R-value, which measures resistance to heat flow: the higher the number, the better the material slows heat from moving in and out of your home. But R-value only tells part of the story. Even a thick layer underperforms when air leaks freely through gaps around recessed lights, plumbing chases, top plates, and the attic hatch.
That is why we treat air sealing and weatherization as the first step, not an afterthought. Sealing those leaks before adding or upgrading insulation is often what turns a drafty, hard-to-heat house into a comfortable one — and it is a big reason many homeowners see energy savings of 20% or more.
Comparing the Common Attic Materials
Every material has a place. Here is how the options we install typically compare:
- Closed-cell spray foam — about R-6 to R-7 per inch, the highest of the common options. It also acts as an air barrier and vapor retarder, resists moisture, and adds rigidity, making it well suited to conditioned attics and tight spaces.
- Open-cell spray foam — roughly R-3.9 to R-4.2 per inch. Softer and more affordable than closed-cell, it seals air well and expands to fill irregular framing cavities.
- Blown-in cellulose — about R-3.2 to R-3.8 per inch. Made largely from recycled paper, it settles into an even blanket across an attic floor and fills around obstructions.
- Fiberglass batt — roughly R-3 to R-4 per inch. A cost-effective, familiar option that performs well between evenly spaced joists and framing.
- Mineral wool — about R-3 to R-4.2 per inch, with strong fire resistance and sound-dampening qualities.
- Rigid board — a high-performance panel used at the roof deck or over framing, where continuous, gap-free coverage matters most.
Vented Attic or Conditioned Attic?
The right material also depends on your overall strategy. In a traditional vented attic, insulation goes on the attic floor and the space above stays cold — blown-in cellulose and fiberglass batt are common, budget-friendly picks here. In a conditioned (sealed) attic, spray foam is applied to the underside of the roof deck to bring the entire space inside your home's thermal envelope. That approach is especially valuable when ductwork, an air handler, or storage lives in the attic, since it keeps that equipment in conditioned air.
There is no single "best" insulation — only the best fit for how your home is built and how you live in it. Matching material to attic type is where real, lasting savings come from.
Not sure which approach fits your home? The Home Insulators is a family-owned company that has served Westchester and Rockland County, NY, and Bergen County, NJ, since 2015. Call us at 914-825-6824 to schedule your free energy audit — we will assess your attic, explain your options in plain language, and show you where the biggest savings are hiding.