Prices, Promotions, styles, and availability may vary. Our local stores do not honor online pricing. Prices and availability of products and services are subject to change without notice. Errors will be corrected where discovered, and Lowe's reserves the right to revoke any stated offer and to correct any errors, inaccuracies or omissions including after an order has been submitted.

Spray Foam vs. Fiberglass Insulation: A Buyer's Guide

Lowe's Editorial Team

By Lowe's Editorial Team
Published July 24, 2024

The right insulation and its proper installation can impact the health as well as longevity of certain aspects of your home. Popular insulators include spray foam and fiberglass. Learn the difference between spray foam insulation and fiberglass here.

Spray Foam or Fiberglass Insulation: What to Choose?

While both these insulation types have their advantages, assess the pros and cons of each product to understand which one is the best one for your home.

What is Spray Foam Insulation?

Spray foam is a complex material that is made from two liquid chemicals, typically, isocyanate and polyol resins. Once sprayed, the foam rapidly expands on the surface. This mixture hardens to fill the gaps and cracks. When dried, the foam creates an effective air and vapor barrier, making it difficult for the heat energy and sound to pass through it.  

Its applications include walls, attic surfaces and under floors. Spray foam insulation comes in two types, namely, closed cell and open cell. Closed cell has cells pressed together so no air or moisture gets in, making it a perfect choice for roofing, crawl spaces and basements. ​Open cell has cells left open for flexibility and softness. This is ideal for use in attics, walls and ceilings. However, it is breathable and can absorb moisture unless properly protected by vapor barriers. 

What is Fiberglass Insulation?

Fiberglass insulation is made from tiny, fiber-like glass threads. It’s made by heating glass at high temperatures, making it melt and then spun into fibers. These glass fibers are further compressed to make rolls, batts, boards and blankets. Its applications include floors, ceilings, ducts, attics, walls and piping. 

Spray Foam vs. Fiberglass Insulation: A Direct Comparison

Both fiberglass insulation and spray foam offer their own unique benefits. Let’s compare the two and find what’s right for you.

Water Resistance

Spray Foam

Spray foam water insulation can prevent water permeation. It creates a protective barrier which can remain water-resistant even during floods. 

Fiberglass

Fiberglass insulation is not water- or moisture-resistant. It can retain water and cause potential damage or deteriorate the structure’s integrity. 

R-Value

The R-value is a measure of the thickness and density of an insulation. It demonstrates how well the insulation can resist the heat flow in and out of the space. The higher the R-value of an insulation material, the better the climate control and energy efficiency of your home.

Spray Foam

Open-cell spray foam can have a 3.5-per-inch R-value. Closed cell one can often exceed up to 7.0 per inch R-value. This showcases how well a spray foam insulation can resist heat flow in and out of your home. 

Fiberglass

Fiberglass insulation provides insulation with an R-value of about 3.2 per inch. Its R-value can decrease over time. It may also need a replacement in 10 years. 

Installation

Spray Foam

Spray foam installation is super easy. Simply spray, and the foam will expand up to 100 times its original size. This expansion ensures better coverage. 

Fiberglass

Fiberglass batts come in various lengths and widths. It requires measuring and cutting batts. In attics, you'll typically unroll the insulation perpendicular to the joists, covering the entire area. This is to ensure they fit tightly in place.  

Check out our blog for a detailed explanation of how to install home insulation.

Cost

Spray Foam

Spray foam insulation can have more upfront costs, but the decreased heating and cooling bills in the long run make it worth the investment. 

Fiberglass

Fiberglass insulation is relatively less expensive as compared to spray foam. 

Durability

Spray Foam

Spray foam insulation lasts much longer. It can stay for about 80 to 100 years. It promises continual performance with minimal possibility of damage. 

Fiberglass

Fiberglass can sag or deteriorate with time. It might need inspection and maybe an upgrade after a while. However, if the conditions in space of installation are well-maintained, fiberglass can also last long. 

Related Tags: