Basement Insulation: A DIY Guide

Properly insulating your basement can provide tremendous financial benefits. If you are using your basement as a recreational area or primarily for storage, having insulation in the basement can add up to huge energy savings. Applying insulation to your basement walls can save you up to $350 per year in some parts of the country, that’s according to the US Department of Energy. This is especially applicable to homes that experience the majority of heat loss to the basement as a result of a very good seal in the upstairs windows and doors of the house.

When it comes to basement insulation controlling moisture is the key. It’s important to know that concrete can be full of moisture. This means that many types of insulation are not suitable for basements, as they are vulnerable to mold and mildew.

In order to successfully install insulation in the basement, you will need to control the moisture that already exists within your foundation. You will need to use a vapor barrier to prevent that moisture from coming out of the foundation into the finished framing where it can lead to mold. This can be easily accomplished with closed-cell foams, either spray-on foam or foam board insulation products. 

Spray foam is the best choice, as it provides a complete seal, giving you a better vapor barrier. A good spray foam installation can be expensive, so if the cost is prohibitory, foam board is going to be your best bet. If you plan to do the job yourself, we’ve outlined some steps below. 

Getting Ready to Insulate Your Basement 

Moisture is always the biggest concern when it comes to basement insulation. You can use plastic or duct tape to do a simple test to make sure there is not too much excess moisture seeping through the walls. Adhere a piece of plastic sheeting to a bare concrete wall with duct tape completely around the edge. Wait two days and check for the presence of condensation. If you find any you know that water is seeping into your basement. 

You will also want to make sure the tie rods are sealed properly. These are the rebar pieces used to hold down the foundation during the pouring process. Use a masonry hammer to tap the rods into the foundation until they are below the level of the floor. After that, you’ll want to use some hydraulic cement to seal off the holes. 

Be sure to only use a little at a time as this type of cement tends to set quickly.  The consistency should remind you of peanut butter when it is mixed properly. Next, spray down the tie rod holes with water. This will prevent all the concrete from sucking the moisture out of your fresh cement. Finally, use a margin trowel to force the fresh cement down into the tie rod holes packing it tightly.

Installing the Insulation

  1. You will want to use polystyrene foam board as your insulation material. Once your cement is dry you can use an adhesive to press the panels to the wall. Solvents can dissolve foam board insulation, so make sure you choose and adhesives which don’t have any.
  2. After you have set your foam board insulation panels you will need to create a wooden grid for your dry wall. Measure 3 inches from the floor and the ceiling of the room mark those measurments, then mark 5 horizontal lines across your foam board that are equal distance from each other. Now you have a guide for creating your grid.
  3. Next you’ll need a hammer drill, a 3/16 inch masonry bit. You’ll want to use 1×3 spruce board to create your grid. Hold your 1×3 boards up to your marks and drill clean through into the concrete wall. Fasten the boards using 4 inch spring spikes.

4. After you have secured your horizontal boards, screw in the vertical boards using drywall screws. Putting the vertical boards on top of the horizontal ones will leave a nice gap for any electrical wiring that needs to be installed in the future.

5. Finally, install your drywall! It is recommended that you use a variety that is resistant to moisture for down in the basement.