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Encapsulating a crawl space is a common way to deal with moisture or flooding. It is also an easy way to quickly get control of the air quality in the home and lockout rodents and insects. When you’re thinking about “green-ovating” your home, or simply getting control of the moisture or humidity, when you have a crawl space, you must encapsulate.

Encapsulation does a great deal for the crawlspace and for the home above.

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What the process is and what it does

The practice of encapsulating or “sealing off” a crawlspace is done to lock out moisture and cut off the connection between moisture, water and the joists of a home. By running a vapor barrier down the walls of a crawl space to completely cover the floor, you essential separate the outside from the inside of the home.

This vapor barrier will be the flexible membrane between the walls and floor and the rest of the home. A properly designed vapor barrier will limit the transfer of moisture through it while regulating the speed at which air will naturally pass through. This helps to limit and control the amount of moisture that will find its way into the air space and completely segregate liquid water and direct it to a sump location.

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5 helpful tips when having a Vapor Barrier installed in your crawlspace:

1.) Not all vapor barriers are made for this task – careful. There are many products out in the world that claim to be able to fully encapsulate a crawl space. Make sure that your vapor barrier has a low “perm” rate and that it is at least 14mil thick. If you’re planning to use the space for storage make sure that a flexible sub-flooring product is also placed on top of the vapor barrier to protect it.

2.) Cover the walls too – all too often contractors forget to also encapsulate the walls of the crawl space when installing a vapor barrier. This can still allow water and moisture into the basement and therefore render the whole project useless. Take care to make sure it’s installed properly.

3.) Don’t use sprays. – Sealants and sprays aren’t designed to be applied on the interior of the basement. They are good in many circumstances as the “first line of defense” but as the last, they can’t hold the pressure and moisture trapped in a wall.

4.) Install a sump and a dehumidifier – to totally control the moisture level in the crawl space it’s imperative that you have a sump pump and a dehumidifier installed. Moisture will still exist, although not to dangerous levels, but a sump will remove any liquid water your encapsulation traps, and the dehumidifier will deal with any residual moisture that naturally collects in the space.

5 Helpful Tips For When it is Time to Encapsulate Your Crawl Space

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Many homeowners try to cut costs and increase their home's comfort level by installing a crawl space vapor barrier. This will instantly make your home healthier for you and your family, and prevent moisture damage, mold, mildew, foul smells and odors.

Most homeowners tend to look at their crawl space as separate space from their home, but in reality, the two are one. Water vapors that surface from the ground are continuously entering, creating undesirable conditions for you, your family, and your home.

Purpose

The purpose of a crawl space vapor barrier is to stop moisture and wetness from entering and affecting the floor and walls of your basement. Moisture tends to flow from warmer to colder spaces.

Many homeowners don't realize the importance of the proper installation, in order to keep moisture and water vapors from getting in the walls and floor of your basement-- condensation can lead to expensive structural damage. Also, if you can help control the moisture and dampness, you can greatly reduce the amount of energy required to cool and heat your home.

Preparation

When considering the installation of a vapor barrier, take into consideration two spaces in your home; the crawl space and the attic. Humidity tends to build in the walls of both these areas causing mold, mildew and dry rot. This can cause severe health issues for adults and children, especially for those with asthma, breathing difficulties, and allergies. In addition, it can cause severe structural damage to your home.

Some homeowners think that because they insulate the floor joists there is no need to do any additional work, but these items do not serve the same purpose!

Tips for Installation

One of the most popular do-it-yourself vapor barrier products is polyethylene, or plastic sheeting. This plastic sheeting comes in various thicknesses; 4mm, 6mm and 10mm.

With today's technology, this product is made from a high quality material, resistant to rips and punctures. Always check the soil so there aren't any objects or materials that may damage the lining. The slightest puncture, rip or tear could compromise the entire system.

Always, make sure the space is dry before you begin any repairs. To remove the moisture, you may need a dehumidifier.

Overlap the barrier a minimum of 12 inches on the side walls. Be sure it is tight. Use furring strips and masonry nails to firmly secure the lining then caulk along the joints.

Seal all the seams with a heavy duty tape. However, it is recommended not to use tapes that are not specially designed for sealing vapor barriers. When working in the basement you will be forced to contend with pipes, make the proper cuts and seal securely with tape.

The completion of your crawl space vapor barrier will be the best investment you can make in your home.

Crawl Space Repair Without a Fan or Vent

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Crawl spaces are inherently dirty smelly places that can contain all types of unwanted odors from mold & mildew to urine & feces. Some areas of the country can even have soil underneath the home with odorless, harmful gases like radon gas. I'm a big believer that the best long-term solution to solve these problems is to encapsulate the air underneath the home with a liner system. It is a inherently impossible to keep rodents, bugs and mold out of the area underneath the home since the soil is exposed - but it is relatively simple to create a barrier between the home and crawl space the keep out all these unwanted nuisances.

I had a very nice lady write me the other day telling me about this house she had just purchased that formerly had many cats living in the crawl space and they left behind the smell of a giant litter box underneath her home. The odors were coming up through the wooden floor and creating a very fowl smell in the house. She told me she tried all different solutions: spreading baking soda, spraying an enzyme treatment originally intended for carpets & laying down new top soil - needless to say none worked. I wrote her back, apologized for her wasted time and suggested that she treat her crawl space like a wild beast that you can't defeat, only contain. She took my advise, installed a crawl space encapsulation system and the smells immediately went away.

Permeability Rating

Encapsulation systems are rated by permeability - 0.000 is the best, normal plastic is 0.01 and wood is 0.2. To stop all smells, moisture and gases look for an encapsulation liner system with a 0.000 permeability rating. A zero perm liner will also completely weatherize the crawl space and save on energy bills since the outside air won't be able to leak into the home.

Thin Liners Don't Encapsulate the Crawl Space

I can't tell you how many times I've received a call or been sent an email from a homeowner telling me how they went to Home Depot, bought a liner system as thin as a trash bag, spent an entire weekend installing it then didn't solve their problem. Cheap store bought liners are typically 6-12 mil, 0.01 permeability and even new they don't stop gases like Radon - they are also easily chewed through by bugs and rodents leaving the crawl space a year later leaking air like a sieve.

What to Look for

40 - 60 mil thickness, 0.000 permeability and antimicrobial so mildew can't grow on the liner. Encapsulation systems don't need a contractor to install (although trust me they won't tell you that). Look for the Energy Star Rated logo.