Does My Crawl Space Need a Vapor Barrier?

At first impression you may think that the layer of flooring and insulation between you and the crawl space is enough. But unfortunately oftentimes this is not the case.

A vapor barrier, also known as a moisture barrier, is actually the minimum amount of protection you should have in your crawl space. Read on to learn why your crawl space needs a vapor barrier.


A vapor barrier is a plastic liner that covers the ground of your crawl space.  Its purpose is to block vapors and moisture in the soil from getting into your crawl space.  

Your house is made of materials that are porous, so the air in your crawl space gets into your home. Additionally, the air that your HVAC unit circulates is pulled -at least in part- from the crawl space. 

Porous materials also let moisture into your home. Damp air allows mold to grow, forces your HVAC system to work harder, contributes to the decay of your wooden flooring structure, and draws the interest of damaging insects.


When you install or replace the vapor barrier in your crawl space, you’ll start to notice a significant improvement in air quality.  The air in your home should become less humid, odors should dissipate, and your HVAC bill may even lower.  

But if this doesn’t happen, or if you find signs of a developing problem, you will probably have more questions.  Here are the most likely issues:

  • Water in your crawl space: if you have more than just dampness in your crawl space, a vapor barrier may not be sufficient.  It’s only meant to stop moisture, not water.  If you have puddles of water under your home when it rains, you will need crawl space waterproofing.  As rainwater collects in your crawl space, it will cause the vapor barrier to float around and render it ineffective. 
  • Dehumidifier Needed? If you install a vapor barrier, but the air still feels clammy, it may be time for a dehumidifier. 
  • If you find mold, please do not try to remove it yourself.  For your safety, please have it evaluated by a professional, first.  We explain how mold removal and remediation is done, provide pricing, and describe options on this page


You will want to find an experienced local company, and request a quote.  Most contractors and waterproofing companies provide free estimates; make sure they provide the quote in writing, and clarify how long the pricing is valid.  

If you live in Charlotte or the surrounding states, contact Fresh Air Companies.  We specialize in waterproofing and provide free estimates.  Our quotes are valid for a year after issue, and we offer the best warranties in the business.  We will schedule an appointment for you with one of our experienced project managers; they will evaluate your home and recommend the best course of action for you, to keep your home strong and healthy for years to come.

Just had Fresh Air Tech address and resolve a chronic moisture problem in our crawlspace. I'm very pleased with the entire process. Company owner Jay is the opposite of the pushy salesmen we spoke with at other outfits. And my final invoice was less than we agreed to, because the Fresh Air crew found a way to solve one of my issues with less labor and therefore a reduced price. Happy to recommend these guys.
Frank Alexander
Frank Alexander
16:48 23 Oct 23
Knowledge based company with excellent customer service, efficient response and work quality. Loved each tech I worked with, they put human in the definition of being human. Can't stand scripted robotic responses and you won't find it here.
Makhi Mitchell
Makhi Mitchell
00:55 18 Nov 19
Amazing work. Bought a house built in the 60s that had never had ducts cleaned. Before and after pictures blew me away. Crew was so professional. Recommend Highly!
Renee Shumaker
Renee Shumaker
02:32 15 Jul 18
Este lugar me da buenos opciones..
Florencio Solano
Florencio Solano
22:26 17 Aug 17
I recently discovered a mild mold problem in my crawlspace and begin my search for a company to remediate. Fresh Air Tech. seemed to have the best treatment plan for my situation and was the most competitive when it came down to the price. I had the mold removed/sprayed with prevention chemicals, crawlspace cleaned with a new vapor barrier and a dehumidifier installed. I didn't know what to expect never having to deal with this before but I can ensure you these guys do not cut corners and did an excellent job. The cleaning crew (3 guys) arrived about 8AM and were under the house until about 4:45PM cleaning and sanding taking a quick 30 minute lunch break around noon. They returned the next day to install the vapor barrier and to finish cleaning up. The dehumidifier also comes with a monitor that displays the temp and moisture level down in the crawlspace which i thought was pretty cool. Excellent job, thanks again team.
Gary Young
Gary Young
03:16 14 Aug 17
Great company - thanks Neil & team for a job well done!
Carl Zimmerman
Carl Zimmerman
15:31 26 Jun 15
Mike, your page is looking Great!
Geary Morris
Geary Morris
15:10 31 Oct 13

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Fresh Air Technologies provides Charlotte area clients a FREE 11-point Attic & Crawl Space Inspection Report! Please contact us for a free air quality estimate and free air quality inspection services.

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