The crawl space has an integral role towards a home’s overall value as well as the living space above. Most homeowners in Corryton 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.
The Best Clean Crawl Space In Corryton TN
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.
Crawlspace Vapor Barrier Installation
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.
What to Do About Basement Waterproofing Before It's Too Late
Installing a crawlspace vapor barrier is not rocket science. It is not physically difficult. Whether installing a quality vapor barrier in a vented crawlspace or doing a complete crawlspace encapsulation, it only takes a little time, a little patience and a willingness to crawl around on your hands and knees for a couple of days.
Where to Buy a Crawlspace Vapor Barrier
There are many places to purchase a crawlspace vapor barrier. An on-line search will provide contact information many retailers. And the products they offer vary from inexpensive clear plastic to woven and coated fabrics much like swimming pool liners. The inexpensive liners can also be purchased from many hardware stores and home centers.
What Vapor Barriers Are Available
The inexpensive vapor barriers will do the job but it's been our experience that they tear easily, don't stay in place, and become brittle and crack after four to five years. But they are inexpensive.
The alternative is to spend a couple times more initially and purchase a product with a twenty five year warranty. The reinforced or woven products require no more time to install than the inexpensive shorter-lived products.
The real question is whether an installer wants to spend a couple of days crawling around in a damp crawlspace every four or five years, or wants to spend a little more initially and have an installation that is maintenance-free and will last for decades. Personally, it makes more sense to me to do it right the first time and be done with it.
Installing the Vapor Barrier
Whether doing a full crawlspace encapsulation or simply installing a vapor barrier in a vented crawl space, the installation of all products have a lot in common.
First, the floor needs to be completely covered, with all seams overlapped 6" to 12" and sealed with tape. While duct tape is a wonderful product with countless uses, it does not do a good job sealing the seams of a vapor barrier. A quality, water-proof vinyl tape designed specifically for sealing the seams is recommended.
Wrapping the Crawlspace Piers
Second, the floor material needs to be sealed around all the foundation supports. Whether steel posts or concrete block piers, it is necessary to prevent the migration of water vapor from around the foundation supports. This is usually done by wrapping the piers - sealing the piers with the vapor barrier 6" to 12" up from the floor. This provides a sealed pier to which the floor material can be sealed to using seam tape.
Wrapping the piers can be a little problematic. No safe, nonflammable, nontoxic construction adhesive is effective with the available materials except for a newly developed, patented proprietary wall and pier liner. The vapor barrier is typically applied to the piers using a combination of tape, mastic, caulk, and mechanical fasteners. The mechanical fasteners require that holes be drilled into the piers using a masonry bit and hammer drill. This adds exponentially to the installation labor.
The patented wall and pier liner can be applied to most any surface using a low VOC and nontoxic construction adhesive. Being low VOC and nontoxic, it is nonflammable and safe to use in the confined area of a crawlspace. It can be safely installed in a fraction of the time. It is the only material of its kind and can be ordered from it manufacturer.
Sealing the Crawlspace Walls
Finally, regardless of whether you're installing a vapor barrier in a vented crawlspace or doing a full encapsulation, it is necessary to seal the floor material to the crawlspace walls. Most experts agree that this is a vital step for a well installed barrier or encapsulation.
If installing a vapor barrier, the floor material should be sealed to the wall 6" to 12" above the outside grade. Like wrapping the piers, most companies recommend the tape-caulk-mechanical fastener combination. The mechanical fasteners should be placed every two to three feet long the perimeter of the crawlspace. If taking this approach, be sure to use a respirator as concrete dust can cause severe respiratory problems.
If doing a full encapsulation, the entire wall, a minimum of three inches down from the sill plate to allow for a pest control inspection, should be sealed. Enough floor material can be purchased to extend up the walls or, the method we've found easiest, the wall is covered and sealed with a wall liner and the floor material is sealed to the wall liner using seam tape. Regardless of which method you use, the vapor barrier must be securely attached and sealed to the wall.
The manufacturer of the pier wrap also makes a patented wall liner that attaches to and seals the wall in one simple step. It reduces installation time by several hours. Like the pier wrap, it is available from the manufacturer.
Crawl Space Masters Specializes In Crawl Space Encapsulation in Corryton TN.