What Type Of Insulation Is Best For Basements?

You need insulation in your basement, but what product would be best? Does it matter what type of insulation you install in the basement?

South Central Services has insulated hundreds of new and existing homes in areas like McConnellsburg, Hagerstown, and Greencastle. Spray foam is one of several options for basement insulation products, but what type of insulation is best for your basement depends on several factors.

By the end of this article, you will understand:

• What factors influence insulation needs in basements
• Which insulations can be used in basements
• What insulation is best for your basement

How Your Basement Is Used Influences The Insulation You Need.

You may not know this, but your basement only needs insulation in one place: the ceiling or the walls. One of these two areas needs to be insulated to meet building codes.

You don’t have to insulate both your basement ceiling and walls. Depending on your insulation products, insulating both areas can actually create a headache for your HVAC system.

Generally speaking, homeowners insulate their basement ceiling when they don’t plan on finishing the basement. An effective thermal layer between your living space and your basement is enough to prevent cold infiltration from increasing energy costs. However, some homeowners finish their basements and put soundproofing insulation in the ceiling. Which insulation is best for the ceiling depends on the goal of the basement space.

Basement wall insulation can be installed for a finished or unfinished basement. If you finish your basement, the wall insulation will be installed differently. Additionally, some insulation products are only available for finished basement walls.

There is no best basement insulation. While we often recommend spray foam for its superior performance, which insulation is best for you depends on your needs and goals for the space.

Do The Surfaces In My Basement Matter For Insulation?

Basements have some type of masonry walls. Stone, concrete, and cement block are all examples. Generally, the type of insulation you can use in your basement is not affected by the kind of masonry walls.

Some basements do have more moisture concerns than others. For example, a cellar with a dirt floor has more moisture than a basement with a concrete floor. Some below-grade spaces have standing water problems, and others do not. If your basement has these moisture concerns, you need to address waterproofing measures before installing insulation.

Which Insulations Can Be Used In Basements?

The following section will cover every insulation product that can be used in a basement. We’ll address where the insulation can be installed and when it is best to use so you can determine which is best for your basement. Here’s a preview.

1. Faced fiberglass batts
2. Faced fiberglass blankets
3. Soundproofing products
4. Open cell spray foam
5. Closed cell spray foam

Let’s examine each of these insulation products in more detail.

1. Faced Fiberglass Batts

Fiberglass batts are one of the most popular and common insulation products available. Batt insulation is used in almost every area of the home, even when it shouldn’t be. Fiberglass batts are relatively inexpensive and you can install them yourself.

For basement applications, the facing of a fiberglass batt is important. These facings act as vapor barriers. While the vapor barrier will not be effective if the insulation is installed incorrectly, it is best to have a vapor barrier when dealing with the below-grade space of a basement.

Can Batts Be Used In A Finished Basement?

You can install fiberglass batts in your basement ceiling to act as a sound barrier. If you plan on finishing your basement, you’ll still need to insulate the walls. However, batt insulation works well for dampening sound transfer.

If you are finishing your basement, you can also install fiberglass batts in the walls. We do not recommend fiberglass for basement walls, but it is popular for its low investment cost and DIY capability.

Can Batts Be Used In An Unfinished Basement?

Fiberglass batt insulation is not an option for an unfinished basement wall. Fastening so many batts of insulation to a masonry wall would be tedious and difficult.

You could stuff your unfinished basement ceiling with batt insulation, but this is not the best option. While fiberglass batts effectively dampen sound transfer, they offer average performance at stopping heat transfer. You want an effective barrier between the cold, unfinished basement and your conditioned living space.

If you aren’t planning on finishing your basement, there are better insulation options than fiberglass batts.

2. Faced Fiberglass Blankets

Faced fiberglass blankets may not be as popular as DIY insulation, but they are common for basements. As a fiberglass product, blanket insulation still has a lower upfront investment cost.

Like fiberglass batts, fiberglass blankets need a vapor barrier facing when used in basement applications. The moisture of below-grade spaces makes the vapor barrier necessary.

Can Blankets Be Used In The Basement Ceiling?

Faced fiberglass blankets are not used in basement ceilings. The size of the insulation blanket is not a good fit for ceiling cavities.

Can Blankets Be Used For The Basement Walls?

Faced fiberglass blankets are an option for basement walls, whether you plan on finishing the basement or not.

For an unfinished basement, faced fiberglass blankets are fastened to the masonry wall. When these blankets are installed, it is important that there are no air pockets between the insulation and the wall.

For a finished basement, the installation process of fiberglass blankets is the same. However, a finished basement needs drywall. After installing the insulation blankets, a wood-frame wall is constructed in front of the insulation.

When on a budget, faced fiberglass blankets are the superior option for basement insulation. While other products offer better performance, blankets outperform batts.

Most of this performance difference is due to the size of the insulation blanket. Batts are smaller, leaving more room for error, gaps, cracks, and sagging. Blankets have a larger surface area, minimizing the potential for insulation gaps.

3. Soundproofing Products

If you plan on finishing the basement, you likely have specific plans for that space. For many homes in southern Pennsylvania, the finished basement is home to a game space, media room, or guest suite.

For any of those options, you will want effective soundproofing between the rest of the home and the basement. No one wants to disturb their guests after they’ve gone to bed or listen to their kids’ video game tournament echo throughout the house.

While the basement walls will still need an effective insulation product installed, the basement ceiling will need soundproofing products. Fiberglass batt insulation can dampen sound, but not like a professional soundproofing product.

Check out our friends at Soundproof Cow for more information on the best soundproofing products for basement ceilings.

4. Open Cell Spray Foam

Open cell spray foam insulation is the more affordable of the two types of spray foam. However, open cell cannot create a vapor barrier. Without a vapor barrier, open cell spray foam is only available as insulation for basement ceilings.

While open cell cannot create a vapor barrier, it can create an airtight seal. Open cell spray foam is also useful for dampening sound transfer.

Open cell spray foam in the ceiling is an option whether you need a sound barrier or a thermal barrier. However, there may be more cost-effective options than open cell.

If you have a basement space you don’t plan on finishing, we recommend open cell as an option for the basement ceiling. The ceiling insulation is crucial to form a barrier between the conditioned living space and the basement. Unlike fiberglass batt insulation, open cell spray foam creates an airtight seal. No cold air can infiltrate the ceiling and make your floors cold.

It is important to note that if you opt for spray foam insulation in your basement, you will need to find a qualified contractor to install it. Unlike fiberglass, spray foam insulation should not be done as a DIY project.

5. Closed Cell Spray Foam Insulation

Closed cell spray foam insulation may be more expensive than open cell, but it is also more versatile. When it comes to basement insulation, closed cell spray foam can go anywhere: the ceiling, the walls, even the band boards.

Closed cell spray foam creates a vapor barrier at approximately 2 inches depth. Unlike faced fiberglass insulation, the vapor barrier of closed cell spray foam is seamless.

Is Closed Cell Useful For Unfinished Basements?

Closed cell spray foam can be installed in the ceiling or on the walls of an unfinished basement.

Depending on what your basement ceiling looks like, closed cell spray foam may not be the best choice. For example, some basements have protrusions from plumbing and electrical wiring. While the spray application of spray foam does create a seamless seal, it can also enclose these protrusions. We do not recommend sealing these off.

As for the basement walls, closed cell spray foam is the simplest to have installed. Your contractor will be able to install a few inches of closed cell directly against your masonry walls. Because spray foam adheres to substrates, no fastening is necessary.

Is Closed Cell Useful For Finished Basements?

Closed cell spray foam can also be used for the walls in a finished basement. Instead of being spray-applied directly to the basement walls, the foam is installed against a wood-frame wall constructed in front of the masonry walls.

If you insulate your basement walls with closed cell and later want to finish your basement, you can. All you have to do is construct the wood-frame wall in front of the closed cell insulation that is already installed on the masonry wall.

Closed cell spray foam is our recommendation for finished basements. It provides a seamless air and vapor barrier, which faced fiberglass blankets cannot offer. Fiberglass insulations in the basement risk condensation issues, but closed cell spray foam does not.

We do not recommend closed cell spray foam in the ceiling of a finished basement. Finished basements must have wall insulation, which means ceiling insulation is unnecessary. The only time you would insulate both your walls and your ceiling is if the ceiling insulation is for sound-dampening purposes.

The Bottom Line About The Best Basement Insulations

Depending on how you plan to use your basement, you have many options for insulation. Your budget will also influence which is best for you.

If you plan on insulating your basement walls, our recommendation is closed cell spray foam. However, if spray foam is out of your budget, your next best option is faced fiberglass blankets.

If you plan on insulating your basement ceiling, our recommendation depends on the protrusions in your ceiling and how you plan to use the basement space. Fiberglass batts, open cell spray foam, and soundproofing products are all potentially best for your situation.

Now that you understand what products are available for your basement, your next step is to:

• Estimate the cost of open cell spray foam for your basement
• Estimate the cost of closed cell spray foam for your basement
• Discover how to find a qualified spray foam insulation contractor