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Tips To Insulate Your Home's Crawlspace

by April Carlson

If you live in a home with a crawlspace under any of its floors, it is a good idea to check the condition or existence of your crawlspace insulation. A crawlspace without proper insulation can create a cold and wet environment under your home, especially in the winter. Here are three tips to help you insulate your home's crawlspace and eliminate these problems.

Insulate Your Crawlspace Walls and Ceiling

If your home was built before 1990, it was most likely built without energy conservation building codes and without wall insulation in the crawlspace. Your crawlspace may also have no insulation on its ceiling, providing no floor insulation to the rooms above it and creating cold floors in the winter. If you discover this condition in your home, it is best to insulate the walls and ceiling in your crawlspace to remedy the problem.

Before you can install wall insulation on the crawlspace walls, you need to seal over any wall vents to the outside. In the past, walls vents were installed on home crawlspaces to help vent moisture to the outside. Unfortunately, they allowed more moisture to come into the crawlspace and collect there. You can seal off wall vents from the exterior, using a vent cover, which you can find at most home improvement stores. Or, you can also attach a piece of plywood over the exterior of your vent, sealing its edges with caulking.

Use the Right Type of Insulation

The U.S. Department of Energy recommends to install insulation with an R-value of at least nine in your floors. Also, because crawlspaces are prone to moisture, leading to mold and mildew, it is best to install a waterproof insulation. The best type of waterproof insulation for your crawlspace walls and ceiling, especially if you live in a region that has cold winters, is closed-cell spray foam or a rigid insulation board. 

You should avoid installing fiberglass and open cellulose insulation, as they act like a sponge in the presence of water. Then, once this type of insulation becomes wet, it not only becomes a breeding ground for mold and mildew, but the moisture makes the insulation ineffective. The air pockets in insulation are what gives insulation its ability to work properly, and it stops working when the air pockets become full of water. 

Insulate Your Crawlspace Floor

In existing, older homes, many crawlspaces were not finished with a concrete floor when the home was built. In this situation, the dirt floor of your crawl space needs to be insulated. 

First, remove any items stored in your crawlspace and level out the dirt floor, using a shovel and garden rake. If there are any puddles of standing water, fill these in with dirt to eliminate the collection area. Then, you may need to correct any exterior drainage issues on the outside of your home. Install downspout extenders from your roof gutters to deposit rainwater five to ten feet away from your home's foundation. Also, grade the soil so it slopes away from your home's foundation at least six inches for every ten feet of length.

Now you can spread a layer of six millimeter-thick plastic vapor barrier sheeting over the dirt floor all the way to each of the home's foundation walls. This inexpensive solution will act as a vapor barrier to keep the moisture in the soil from entering the air of your crawlspace. Make sure you overlap any seams of the plastic sheeting by one foot, then attach and seal the seams with tape. Last, tape the sheeting to the wall insulation.

If your crawlspace already has a concrete floor, install a floor vapor barrier sheeting across the concrete to seal the floor off and keep moisture from collecting in the space. If you plan to use the crawlspace for storage, be sure to install sheeting durable enough to hold up under foot traffic.

Use these tips to insulate your home's crawlspace. For more information, contact insulation contractors near you.