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.
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.
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.
A Closed, Sealed Crawlspace - What a Really Bad Idea
There are advantages and disadvantages in having a crawl space under your home. Advantages, perhaps, a slightly elevated home may be more attractive than a home on a slab. Plus, you can make repairs and modifications to plumbing, heating, and electrical services.
Disadvantages, a crawl space is an area that is never cleaned. Under the vapor barrier the humidity is always 100% so mold and bacteria are always present. Termiticides, other chemicals, even rodent droppings may be present, and odors and gases that emanate will migrate into the home's living space unless proper ventilation is installed. Whether on a slab or elevated, if radon is present, good ventilation is required.
There are several technologies on the market in regard to moisture control. One is encapsulation, sealing the crawlspace. Though this might lower humidity, it's costly and there is no dilution or replacement of stagnant, poor quality air. Again, if radon is present, ventilation is required.
Another technology is to install a dehumidifier in the crawl space. This can lower humidity, but again will not dilute or replace the stagnant air. Another point to think about is that the dehumidifier will be costly to operate. More importantly, using a dehumidifier requires you to close tightly the crawl space. Thus, the home's living space air quality is going to be lowered because the crawl space air is not diluted and replaced with fresh outdoor air.
Some systems use a dehumidifier control (dehumidistat) to operate a crawl space vent fan. This sounds like it's going in the right direction. However, the technology isn't quite right. Here's why. Suppose the outdoor air is getting worse (wetter). Though the dehumidistat control is in the crawl space, it will quickly recognize this wetter air condition and begin ventilation, even though ventilating is going to make crawl space wetter. Another problem with a dehumidistat control is that most of them are not made for the difficult environment of a crawl space, so their warranties are short, 30 days to 1 year maximum for the dehumidistat.
There is another system that uses special technology different from all the others mentioned above. This special technology makes a comparison of the actual moisture content of both the air inside the crawlspace and the outdoor air. The result is that it pauses and does not ventilate when bringing in outdoor air is going to make the space wetter. Then, as the outdoor air is getting drier and is able to improve the moisture and air quality in the crawlspace, then this ventilator moves a lot of air which dilutes and replaces stagnant air, ultimately improving your home's living space air quality.
This system, called the Smartvent, is made in the USA, is used from Florida to Alaska... San Diego to Nova Scotia.
This system is a proven system, and it is the only system to have undergone a year long test where crawl space humidity averaged 46%. Besides the unique technology this system employs, it also has the longest warranty of all ventilators, five years.
Crawl Space Encapsulation Systems DIY
The crawl space has an integral role towards a home's overall value as well as the living space above. Most homeowners don't think twice about their crawl space unless they have to make repairs to plumbing, heating ducts or house wiring. While often thought of as no more than a storage area, it also has a tremendous impact on the overall indoor air quality of the entire home.
By default, the air quality of a crawl space is typically poor. Mold, mildew, radon gas and poor energy efficiency all create several problems. The air that circulates within it eventually makes its way up through the living space. Scientific studies show that up to 50% of living space air originates from the lowest level of the home. With homeowners more concerned about their home's indoor air quality, the encapsulating of crawl spaces has become a popular solution for such problems.
A damp crawl space creates a safe harbor for harmful molds, in addition to dust mites, termites and other bugs that can infest the home. The presence of excessive moisture will also create a serious problem with the probability for the wooden structure of a home to deteriorate. Crawl space vents pose a further problem. While believed to be a solution to moisture problems, they unfortunately make the problem worse. As it turns out, the vents allow cold air and moisture in, which rises into the living area and therefore decreases the heating efficiency of the entire home.
Another all-too-common problem associated with crawl spaces is radon gas. Though it cannot be seen, smelled or tasted, radon is a radioactive gas that can contribute to poor health, including cancer. Radon gas makes its way through the earth, into the crawl space and the home's living space. According to the U.S.E.P.A., radon gas is the number one leading cause of lung cancer in non-smokers.
Ignoring these various conditions is not recommended for both long-term health and energy usage. Fully encapsulating a crawl space - by both sealing and insulating - is a fully efficient measure in addressing such problems. It makes sense to maintain and improve the lower level area in order to maximize healthy living conditions and home resale value.
While there are several systems for encapsulatiing, a zero perm liner system that also insulates and reflects heat provides the most benefits. With a proper floor and wall liner, the area will not only be well insulated, but will seal out moisture, bug infestation and radon gas. Other components to look for in a system include a radon gas-dispersing drain fabric, a radon gas ventilation pipe and a ceiling heat shield.
A complete system with all of the above components will allow any soil gases - including radon gas - that naturally occur under the liner system, to wick through the drain fabric and escape out through the ventilation pipe. While improved indoor air quality is the primary benefit of a sealed and insulated crawl space, the homeowner will also appreciate a bright, clean, and dry storage area; the ridding of musty smells; less energy usage; and tax credits. Contractors encapsulating crawl spaces will have more to offer to their clients when they can assure the peace of mind with improved indoor air quality.