You may not know this, but under your crawl space large amounts of water is constantly rising up near the surface and evaporating. This water vapor then proceeds to rise up through the floor and right into the crawl space. The vapor has two negative effects. First off, it brings odors into your house. Secondly, and more importantly, the water vapor will start to collect, which leads to moisture seeping into support beams, insulation, etc. This leads to mold and can even cause structural damage. To combat this water vapor, a lot of people outfit their crawl space with a moisture barrier (also known as a vapor barrier), which is the most effective way to protect your crawl spaces from moisture damage. While it is generally better to let a licensed professional install them, if you choose to install the moisture barrier yourself, here are a few important tips that you will want to keep in mind.
Make sure the floor is completely clear
Before you go to lay down the material for the moisture barrier, take the time to make sure the floor of the crawl space is smooth and that there aren’t any sharp objects laying around. Make sure to be thorough when checking, because any sharp objects left on the floor could rip through the barrier, making it less effective.
Use the right kind of tape
When installing your moisture barrier, you are going to have to seal the seams with tape. But, although you might be tempted to just use regular duct tape, you shouldn’t. Regular duct tape doesn’t have the strength too reliably hold the moisture barrier together. So, you should use specialty tape, like seam tape, to make sure that your barrier actually works.
Crawl Space Moisture Barrier: Use stakes to hold the plastic down
If you want to keep the plastic the ground firmly in place, try using fabric pegs to help keep the plastic from moving around too much when people are moving around on top of it. I know this sounds counterintuitive, but the holes created by the fabric pegs are too small to actually reduce the effectiveness of the moisture barrier. And as an added bonus, if for some reason water ever gets on top of the barrier (for example, say because a pipe is leaking), the water can actually drain through the small holes created by the fabric pegs.
Plan everything out first
With a job as complex as this, you want to make sure everything is meticulously planned out in advance. For example, accurately measure your crawl space, and get as much information as you possibly can. Likewise, avoid cutting in the actual crawl space; instead you should measure everything out, and then cut everything outside the crawl space. Finally, avoid buying any materials until you have everything planned out and have done research on the best type of materials to use in your crawl space. This isn’t the type of job you take up on a whim, it requires serious planning beforehand.