Compare Spray Foam vs Fiberglass Insulation Costs
Spray Foam Insulation
Spray foam is a relatively new method of insulation, at least compared to fiberglass. The polyurethane foam is sprayed into walls and ceilings, where it expands to form a seal that is air tight and, in some cases, moisture tight.
Spray foam can be used as the primary method of insulation in a new home or as supplemental insulation for a new or existing home. One of the product’s best attributes is the ability to seal off small crevices that other types of insulation can’t reach, but we’ll discuss the pros and cons in detail later on in this guide.
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Types of Spray Foam
Spray foam insulation comes in several forms: one-part formulas in aerosol cans, two-part formulas suited for use with low-pressure sprayers and two-part kits applied with high-pressure sprayers. The aerosol cans are ideal for small do-it-yourself jobs such as adding insulation around a doorway, but the two other methods of application typically require the equipment and training of a professional. Kits for low-pressure sprayers work for smaller jobs; high-pressure is better for big jobs.
No matter how it is applied, spray foam falls in to one of two categories: open cell or closed cell. Closed cell is the denser and more expensive of the two. It insulates about twice as well with an R-value of about 6 to 7 per inch, compared to 3 to 4 per inch with open cell. Closed cell is also moisture tight, while open cell is not, so it should be used in basements or other areas where insulation could come in contact with water.
How Much Does Spray Foam Insulation Cost?
The price of spray foam insulation depends on many factors: the size of the home, which areas of the home are insulated with foam, the type and quality of the foam, your geographic location and the applicator’s experience. Because costs vary so dramatically, it’s not very useful to offer an estimate of total project cost.
The price of spray foam insulation is usually discussed by the board foot, which describes a 12x12-inch space that is 1 inch thick. Open-cell foam usually goes for about $0.45 to $0.80 per board foot, while closed cell costs more like $1 to $1.50 per board foot. (All prices include material and labor.) If you can figure out how many board feet you need covered, you can get a rough estimate of cost.
By the square foot, which is how fiberglass is usually priced, costs range from about $1.30 to $3.50 per square foot of wall space. Open-cell spray foam falls on the lower end of that range, while closed-cell foam usually costs at least $1.75 per square foot.
Keep in mind that prices can be higher for hard to reach areas. Small projects are likely to cost more per board foot than large projects. And these figures are only meant to be estimates - costs vary dramatically from one region to another.
Spray Foam Pros
- Energy efficient - Spray foam insulation naturally expands after it is applied, sealing around crevices and joints where fiberglass can’t reach. Because of this, it is a more energy efficient method of insulation. Your energy bills will be lower than with fiberglass insulation if the spray foam is properly installed.
- Longer lasting - Spray foam doesn’t break down as easily as fiberglass, so it has a much longer lifespan.
- Prevents other types damage - High-quality spray foam insulation comes with the added bonus of protecting your home from pests and mold damage. Pests such as rodents will not be able to permeate the insulation, nor will water if you spring for closed-cell foam.
Spray Foam Cons
- Expensive - Perks such as increased energy efficiency and a longer lifespan come at a price. Spray foam insulation is considerably more expensive than fiberglass - sometimes triple the cost or more.
- Difficult to apply - Spray foam insulation is not advisable as a do-it-yourself project, unless you’re using the aerosol can version for a very small job. Even professionals sometimes struggle to execute spray foam correctly - the job requires precision. Pick your installer wisely, making sure he or she has adequate experience.
- Messy - Spray foam insulation can create a big mess if it seeps through holes, cracks or joints before it dries. Also, it’s fairly easy to miss your intended target in some areas and overspray others.
Fiberglass Insulation Overview
Fiberglass has been around a lot longer than spray foam, so the method of insulation is more familiar to the average consumer. Think of all the garages and attics you’ve seen filled with the pinky fluffy stuff (although the pink represents just one popular brand; fiberglass insulation is sold in lots of different colors).
Fiberglass is made of glass fibers - just as the name suggests. It is often used as a home’s primary method of insulation, as it can be difficult to add to existing homes. However, it can be added in existing homes in easy-to-access places such as attics or in a less-common form called loose-fill, which is described below.
Types of Fiberglass Insulation
Fiberglass comes in two forms: blankets (rolls or batts) and loose-fill. Blankets are best suited for new construction and easy-to-access spaces such as attics, and they must be cut to fit precisely into wall spaces and other cavities. They are far more common than loose-fill fiberglass, which is blown in.
Fiberglass batts are sold in varying densities, each with varying R-values. Standard batts typically have an R-value ranging from 3.2 to 3.8 per inch, while medium- and high-density varieties have R-values of up to 4.3 per inch.
How Much Does Fiberglass Insulation Cost?
Standard fiberglass batts cost about $0.50 to $1 per square foot of wall, including installation. The higher the density and R-value, the greater the price. Batts for the attic cost more than batts for walls, for example, because they need to be denser. Some batts with very high densities cost upwards of $1 per square foot.
Blown-in fiberglass also costs about $0.50 to $1 per square foot.
- Affordable - Fiberglass insulation costs considerably less than spray foam insulation.
- Easy to install - Do-it-yourselfers are far more likely to have success with traditional fiberglass insulation. Spray foam, because of the complexity of installation, was made available to consumers only recently.
- Familiar material - Because fiberglass is so popular and has been around so long, contractors have more experience working with the material. You probably won’t find as many local contractors who are experts in spray foam installation.
- Neater - Fiberglass insulation tends to make less of a mess.
- Not as efficient - Fiberglass has a lower “R-value” than spray foam, meaning it provides less resistance to heat flow. Thus, it is not as energy efficient.
- Settles faster - Fiberglass breaks down and settles faster, leaving you with less insulation than when it was first installed.