How To Insulate Concrete Basement Walls

If your basement walls need insulation, you want to ensure you do things correctly. Which insulation products can be used in basements? Can you do this yourself, or will you need to hire a professional?

South Central Services has insulated hundreds of new and existing homes with spray foam. There are several different ways to insulate concrete basement walls. Which method is best for you will depend on your budget and expectations.

By the end of this article, you will know:

• Why finishing your basement changes how your walls are insulated
• Which insulations are used for concrete basement walls
• Which insulation is best for your budget and expectations

Don't have time to read right now? Check out everything you need to know at a glance.

First, How Will You Use Your Basement?

Are you planning to transform your basement into a living space? You may want to make a game area or entertainment space. The basement may become the ensuite for anyone who visits your home. Many homes in Mercersburg, Fayetteville, and Greencastle have finished basements.

Or, you may not plan on finishing your basement. Remodeling may be out of budget, or you’d rather use the area as storage space. Plenty of homes in our service area have unfinished basements, too.

Finished and unfinished basements are insulated differently. Unfinished basement walls require less work to insulate. You may also choose to insulate your basement ceiling instead of your walls.

Which Insulations Can Be Used On Concrete Basement Walls?

Once you’ve determined that wall insulation is the path you’re taking, you have to consider your insulation options. There are three main insulation choices for concrete basement walls: fiberglass batts, fiberglass blankets, and closed cell spray foam.

Let’s examine each of these options in more detail.

Fiberglass Batts Are A Budget Insulation Option

Batt insulation is classically known as cost-saving insulation. Compared to other products like spray foam, batt insulation is a more affordable investment.

Fiberglass batts are the budget option when finishing a basement. Batt insulation is a common choice by homebuilders and DIY homeowners alike.

Since batt insulation is the budget option, it offers less performance. While you save money upfront, batt does not create an airtight seal or form an impressive thermal barrier. Using batt insulation in the basement also involves the risk of condensation, which can, in turn, lead to mold.

Concrete walls are porous, so cold air and vapor can move through them. Without an airtight seal, any air between the wall and the insulation risks condensation. Batt insulation is prone to issues with gaps and cracks, inviting airflow. Insulating a concrete wall using batt insulation without gaps or cracks would be challenging.

Faced Fiberglass Blankets Are A Better Insulation Option

Fiberglass blankets are a better choice if you still want to save money but want better performance than batt.

Faced fiberglass blankets can be installed DIY or by a professional.

Like batts, insulation blankets are less expensive than spray foam. Blankets also fail to create an airtight seal. However, blankets take up a larger surface area than batts, meaning there are fewer gaps and cracks.

Faced fiberglass blankets can also be used for both finished and unfinished basements. There can still be condensation risks if air gets trapped between the blanket and the wall. However, the risk is lower than when using fiberglass batt insulation.

Closed Cell Spray Foam Is The Best Insulation Option

If you are less concerned about investment cost and more concerned with performance, closed cell spray foam is the solution. While spray foam has a higher price tag than fiberglass insulation, it also offers the best insulating performance.

Since spray foam is spray-applied, it can create a seamless airtight seal. No gaps or cracks when working with spray foam. Closed cell spray foam can also create a vapor barrier, helping to mitigate condensation concerns.

Whether you want a finished or unfinished basement, closed cell spray foam insulation can be used. However, spray foam insulation is not a DIY product.

If you want spray foam insulation, you should hire a qualified professional. DIY spray foam kits are available for sale, but these kits don’t save money and require investing in separately sold personal protective equipment (PPE).

How To Insulate Your Basement Walls With These Products

Let’s look at the step-by-step processes to insulate with these products.

How To Insulate Basement Walls With Fiberglass Batts

You may be wondering how you’d insulate your concrete walls with batt insulation. Concrete walls aren’t like wood-framed walls with cavities to fill with insulation. If you place a batt of insulation against the wall, will it stick?

No, batt insulation will not stick to the concrete. This is why fiberglass batts are only an option for finished basements.

When a basement is finished, a wood-frame wall is constructed in front of the concrete wall. This wall should extend from the floor to the floor joists in the basement ceiling. There should also be an inch gap between the frame and the concrete.

Once the wood-frame wall has been constructed, it can be filled with fiberglass batt insulation. For best results, size the batt insulation to fit the wall cavities precisely, preventing gaps in your insulation.

How To Insulate Basement Walls With Faced Fiberglass Blankets

Blanket insulation is an option for both finished and unfinished basements. In either case, it is installed directly against the concrete walls.

Faced fiberglass blankets take up significantly more surface area than fiberglass batt. Blankets of insulation can adhere to a basement wall using a mechanical fastening system like concrete nails.

If you do intend to finish your basement, you’ll still need to construct a wood-frame wall. The insulation blanket will exist as a layer between the wood-frame and the concrete. This wood-frame wall will allow you to install drywall to finish the basement.

No wood-frame wall is necessary if you aren’t planning to finish the basement. Just install and fasten the insulation blankets directly against the wall.

Be sure to install the blankets flush against the wall to prevent any air or condensation from forming between the blanket and the wall.

How To Insulate Basement Walls With Closed Cell Spray Foam

An unfinished basement can have a layer of closed cell spray foam applied directly to the concrete wall. Since drywall does not need to be hung, there is no need for a wood-frame wall.

For a finished basement, closed cell spray foam is applied to a wood-frame wall. This wood-frame wall should extend from the floor to the floor joists in the basement ceiling. There should be a 1 inch gap between the wood wall and the concrete walls. Then, closed cell spray foam is applied to the new wall.

The inch gap eliminates the wicking of moisture from the concrete wall.

The Bottom Line About Concrete Basement Wall Insulation

There are different methods and products available for concrete basement walls. If you have room in your budget, closed cell spray foam insulation is the best option available. Closed cell creates an airtight seal to stop infiltration. Concrete is porous, so without an airtight seal, cold and moisture can invade your home.

If spray foam is out of budget, there are other insulation options: fiberglass batts and fiberglass blankets. Fiberglass cannot create an airtight seal, so it offers lower performance. There is also the risk of condensation from the porous concrete. If you opt for fiberglass, we recommend fiberglass blankets for their relatively better performance and lower condensation risk.

If you don’t plan on finishing your basement, you could also consider basement ceiling insulation. With a smaller surface area, ceiling insulation may be more affordable.

Now that you understand how concrete basement walls can be insulated, your next step is to:

• Compare insulation options for your basement ceiling
• Estimate the cost of insulating your basement walls with closed cell spray foam