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Crawl Space Insulation Guide: How To Install Rigid Foam Board On Crawl Space Walls

One of the best things you can do to your home is to install rigid foam insulation in the crawl spaces. The advantages of doing so are many. First, the crawl space stays dry, discouraging rot and mold growth. In addition, floors above the crawl will feel warmer to your bare feet during winter, making your overall indoor space more comfortable. As if thats not enough, crawl space insulation will leave more money in your pocket, by saving energy and lowering your cooling and heating bills. The only downside is that it involves a lot of crawling around below the house, but this is a small price to pay to enjoy all these benefits. Heres a step-by-step guide on how to install rigid foam board on your crawl space walls.

Things Youll Need

Rigid foam insulation Tape measure Expanding foam insulation Heavy-duty scissors Construction adhesive Utility knife Caulk gun Plastic sheeting (6-mil) Straightedge

Crawl Space Insulation: Steps To Insulate The Walls

Measure the height and width of every wall in the crawl, and multiply the results to determine its square footage. Allow for errors by adding 10% to each result. Order the right amount and choice of rigid foam insulation by using these numbers.

Next, measure the length and width of your crawl space itself. Determine its square footage and add 10%. Add these numbers to the wall footage above and use it to find out the right amount of vapor barrier.

Hold one end of the sheeting against the crawl walls far end, and spread it along the length of the wall, ensuring that you pull it past the end of the wall by at least 2-3 feet. Using a pair of scissors to cut the sheeting and measure it. Do the same for the remaining walls.

Run down generous amounts of adhesive on every wall. Position the plastic sheeting immediately on one wall, ensuring that it extends to the walls on the other end, and trails over the floor. Press the sheeting in place by running your hand over it. Do the same for the remaining walls.

Make sure you smoothen out the excess plastic at the ends prior to layering the next material on top of the wall. This is very important because it ensures that the installation is moisture- and air-tight.

Using a utility knife and straightedge, cut each of the rigid foam boards to fit the height of each crawl space wall. Cut the insulation board to fit any remaining gap at the end of each wall.

Cut the rigid foam into small pieces to fit around the walls perimeter, and in between the joists, and then glue and install them. Next, spray expanding foam insulation to seal any small gaps and hold the insulation in place.

Spread the remaining vapor barrier across the floor of the crawl space. Overlap the rows as you see fit and extend the plastic by at least one foot over the preceding piece. Lastly, run up the plastic one foot up the exterior walls, then glue and hold to create a strong bond.

Follow this detailed guide to install rigid foam board properly on your crawl space walls, and make your home more energy-efficient and comfortable to live in.

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