The crawl space has an integral role towards a home’s overall value as well as the living space above. Most homeowners in Edgewood Knoxville 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.
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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 encapsulating, 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 gasses – 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.
Addressing Moisture, Mold and Radon Gas in Basements and Crawl Spaces With Application of a Deep-Pen
If you get three general contractors together and the topic of discussion turns crawlspaces and moisture control, you will probably hear six opinions. Even the experts seem to have different and often conflicting opinions about what tack is the best to take.
There has been much research on crawlspace encapsulation during the past decade. The US Environmental Protection Agency, the US Department of Energy, the ZEBRAlliance at Oak Ridge National Laboratories, and a non-profit research organization called Advanced Energy have all done excellent and groundbreaking research in the area of crawlspace encapsulation. Their research findings were instrumental in the last revision of the International Building Code. They all agree in a few, very important areas.
When considering your home, think of it as a single system. Your HVAC system, insulation, windows, attic, living space, and crawl space all work together. All of these building components need to be optimized and balanced to achieve maximum comfort, performance and energy efficiency. Your crawlspace is an important part of this system.
Your house is like a giant chimney. By natural convection, air is drawn in through crawlspace vents and air leaks. Because warm air rises, the outside air is drawn through the living space (along with mold spores, odors, and moisture) and exhausted through the attic. In the summer, your crawlspace is naturally cooler than the ambient outside temperature. So when the warm, humid outside air reaches the cooler crawlspace surface areas, the moisture condenses on framing, plumbing, wiring, insulation and especially HVAC ductwork and "sweats", just like an iced tea glass sweats on your kitchen table in the summer. In the southeast it is not unheard of for crawlspace humidity to approach 100% and actually rain inside the crawlspace.
The moisture in your crawlspace creates an ideal environment for wood destroying organisms, mold, and mildew. It can saturate and destroy the effectiveness of your insulation and promote wood rot. And because of the chimney effect, the humid crawlspace air, full of mold and mildew spores, eventually finds its way into your living space creating an unhealthy environment and causing your air conditioning to work overtime to dehumidify the air. Just a vapor barrier might help a bit, but most of the moisture is coming from outside, not your dirt, crawlspace floor.
So, the alternative to a vented crawlspace is an encapsulated (sealed) crawlspace. Crawlspace encapsulation involves sealing all outside vents, installing a high-performance vapor retarder on all exposed wall and floor surfaces at or below grade, insulating the walls and rim joist, and conditioning the air.
The prevailing research claims that by insulating the walls and rim joist, it is unnecessary to insulate the floor. However, if the existing floor insulation is in good condition, leave it in place. We generally recommend a rigid foam board insulation that is fire-retardant, low VOC, and offers an R-13 value or greater. It cuts easily and can be used for sealing existing crawlspace vents too. The sill plate should be caulked and paper-faced fiberglass insulation is used to insulate the rim joist.
The building codes in most areas require the air in an encapsulated crawlspace to be conditioned. That generally means adding a dehumidifier or using the existing HVAC system to condition the air. The EPA and the Department of Energy recommend using the existing HVAC system at a rate of one cubic foot per minute of conditioned air per fifty square feet of crawlspace area. A qualified HVAC contractor can add one or two 4" or 6" vents to a system for a nominal cost. The vents are usually equipped with a butterfly valve that can be adjusted to get the desired air flow.
We prefer using this method since the installation of the vents is generally less expensive than a crawlspace dehumidifier. And since running a dehumidifier is about the same as running a small refrigerator, the cost of conditioning the air with an HVAC system is generally less than running a dehumidifier. Remember that you're not trying to heat and cool your crawlspace; you're just adding a small amount of conditioned air. A relative humidity target of 60% or lower is a good place to start.
When comparing high performance vapor barriers, look at puncture and tear resistance. Other than being absolutely water tight, a high performance vapor barrier should also be flexible, fire resistant, low VOC, and lightweight. There is a world of difference between the 6 mil vapor barrier material sold in most hardware stores and a high performance specialty product. Most reputable suppliers will provide samples.
In addition to dramatically increasing indoor air quality and protecting the structure of your home, several research studies from Advanced Energy indicate that crawlspace encapsulation can actually lower energy usage. These studies were done in several parts of the country with varying climates.
Crawl Space Insulation and Its Benefits
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 lock out 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 crawlspace 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.
5.) Look for the right contractor - many of the contractors who specialize in this repair are also in the basement waterproofing business. These contractors, over other general contractors, are preferred because they'll have access to more robust and dependable solutions. They also have the proper training and experience to pull the project off with little effort on your part.
Encapsulating a crawl space will limit moisture and humidity in your cellar and help lower your energy costs. Limiting moisture will help to ensure that any insulation in your floor boards will be working at their peak while keeping the cost of running any air conditioning units to a bare minimum.
Crawl Space Masters Specializes In Crawl Space Encapsulation in Edgewood TN.