Common Types of Insulation, and When to Use Them

Here are the most common types of insulation and when you might use them.

rigid foam insulation boardsstudiovin/Shutterstock

Gone are the days of horse hair, newspapers and straw in our walls to keep our homes comfortable. Now we have five viable types of insulation available at home centers. Here are the most common types of insulation and when you might use them.


Fiberglass insulation is the most common type of insulation found in today’s homes. It comes in batts that fit between framing members such as studs or joists. You can buy  fiberglass batt insulation to fit different sized framing members such as 2×4 and 2×6 walls or joists in your ceiling and floors. The thicker the batt the more R-value it provides. It is a very economical type of insulation and it’s easy to install with just a few tools.

Not sure what R-value is? Here’s what you need to know.

Mineral Wool

Mineral wool is very similar to fiberglass in that it comes in batts and provides similar R-value. It beats out fiberglass as a fire retarder, sound deadener, and it’s resistant to moisture. Mineral wool insulation is heavier, but it also holds its shape better, which makes it easier to install than fiberglass. This type of insulation is also a recycled product so it’s more environmentally friendly than fiberglass batts. All of the benefits of mineral wool bring it in at a more premium price, but it solves a few problems fiberglass batt does not.

Here’s why old-timey mineral wool insulation is making a comeback.

Cellulose Loose-Fill

Cellulose is a type of insulation made from recycled paper that is chemically treated so it’s more resistant to fire. Loose-fill is often referred to as blown-in insulation because it is typically installed  with a motorized blower, through a tube to fill attic spaces to achieve the appropriate R-value. You can avoid using a big, noisy machine and pour it in if you don’t have a lot of space to fill. It is also used to insulate previously uninsulated homes by boring holes in the outside walls and blowing the insulation in. This is the least expensive type of insulation and is a good option if you don’t want to tear into your walls to insulate or for insulating the floors of attic spaces.

It’s not an easy project, but here’s what you need to know to install blown-in insulation in your home.

Rigid Foam (extruded polystyrene)

This type of insulation is the pink or blue foam boards (shown here) that you see at home centers everywhere. It is often used to insulate cement block walls in basements before finishing the space or on the exterior of a home under siding and other places where it’s easier to use a rigid form of insulation.  t is more dense than other types of insulation, so you don’t need as thick a layer to achieve similar R-values. You can buy rigid foam boards in different sizes up to 2 in. thick as 4×8 sheets.

Here’s how to insulate basement rim joists with rigid foam insulation in just a couple of hours.

Polyurethane Spray Foam

Spray foam is probably the least DIY-able type of insulation and it is the most expensive. You can spray at in open cavities at the rim joist or other drafty areas of your house. It comes in a 2-part kit at home centers and it’s extremely sticky and requires you to wear a jumpsuit and respirator. It’s also available in smaller aerosol cans that are much handier and can be used to fill small gaps near vents and other places where air leaks are found.  Spray foam has the highest R-value per inch and it is also a great air and vapor barrier.

Check out our collection of 17 ways to use spray foam insulation at home.