What Crawl Space Encapsulation Is, and What It Is Not

Crawl space encapsulation is a system that isolates your crawl space from the rest of the world so that environment can be controlled. The goal is to improve the air quality inside your home. It is not a sheet of plastic on the ground, it is not a vapor barrier, and it is not waterproofing.

I bring that up first because about half the homeowners I meet tell me their crawl space is already encapsulated. Then I get under there and find a cut up trash bag on the dirt.

What a real encapsulation actually includes

Four parts, and all four matter.

• A quality woven vapor barrier along all the walls and the piers.

• An even thicker woven vapor barrier along the entire floor.

• An Aprilaire dehumidifier, properly sized for your home, to condition that environment.

• Two dehumidistat fans, which blow dirty or smelly air out and help circulate the dry air from your dehumidifier to the extremities of the crawl space.

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Take the dehumidifier out of that list and you no longer have an encapsulation. You have a very expensive liner. The dehumidifier is what actually lowers the relative humidity, and lowering the humidity is what makes the space no longer conducive for mold, mildew or pests.

It is not a vapor barrier

A vapor barrier is code minimum. It is the least you are allowed to have.

It does not isolate the environment, so nobody can control it. It does not regulate relative humidity. And on its own it does not improve the air quality in your home. It is a floor covering, not a system.

If somebody laid plastic on your dirt and called it encapsulation, you paid for a floor covering.

It is not waterproofing

This one catches even other contractors, so do not feel bad if it caught you.

When we install an encapsulation, for all intents and purposes we are building a Ziploc bag underneath your house. But nobody manufactured a custom Ziploc bag shaped to fit your home. So we bend, cut, form and piece together multiple sections of vapor barrier to fit around your foundation, your piers and your obstacles.

Those seams and small gaps can let bulk water in. An encapsulation helps with water, and it solves humidity, but it does not eliminate groundwater and should never be sold to you as waterproofing.

If bulk water is coming into your crawl space, you need a waterproofing system. That means an internal French drain that redirects the water out or carries it to a sump pump where it can be pumped out. That is a different job with a different purpose.

It does not lower humidity by itself

Worth saying plainly because it follows from the first point. The barrier isolates. The dehumidifier controls. An encapsulation without a properly sized dehumidifier does not deliver the thing you bought it for.

How to check what you actually have

Ask yourself three questions.

• Is there a barrier on the walls and the piers, or only on the ground?

• Is there a dehumidifier down there, and is it a real unit rather than a small one from a big box store?

• Does the whole thing look flat, smooth and tidy, or does it look like somebody threw plastic around?

  
  

We pride ourselves on making every crawl space as flat, as smooth and as pretty as possible. Partly so you are not scared to get in there. Mostly so you know we cared while we were doing the work.

If you are not sure what you have under your house, call me at 910 580 1836. I will get under there and show you photos of exactly what is down there.