The crawl space has an integral role towards a home’s overall value as well as the living space above. Most homeowners in Bluegrass 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 Bluegrass 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.
Crawl Space Vapor Barrier Basics
For many homeowners, the first thought in their mind when they consider installing a crawl space waterproofing system is, "But I don't go down there! Why on earth would I do that?"
Good question! And there's a great answer. While you probably don't think about your crawl space, and you may have never even seen your crawl space, it's part of your home. What happens to it has surprising effects the rest of your house.
Water can enter into your crawl space in three different ways: through the earth (or concrete) around your home, from a plumbing leak, or through the air entering your crawl space vents. Whether this moisture enters as humidity or as an all-out leak, a wet crawl space means a headache for you. Moisture collects in anything organic - including wood floorboards, support beams, and some types of crawl space insulation. As the wood swells and warps with moisture, there are nasty results: mold, rot, mildew, bacteria, and dust mites.
What you have beneath your house is no longer a crawl space. It's a habitat. The area is filled with humidity, mold spores, and dust mites. All too soon, mice, rats, snakes, and vermin will take up residence- living and dying in the dark, wet area beneath your home. And there's nothing more attractive to a termite colony looking for a new place to live than all that damp, rotting wood!
Ignore the monster lurking below while you can, but remember that even before your rotting floor and support beams are significantly damaged, you're already being affected. Warm air in your home exits the home through your upper levels, and crawl space air is sucked up into your home. As it's pulled up, nothing is stopping the humidity, mold spores, dust mite waste, and odors coming up with it. In the summer, your air conditioners will be working overtime to remove this humidity. During the winter months, cold air vented into the home hammer away at anything it can reach- including the water heater, hot water pipes, and heating ducts.
In a vented crawl space, insulation is a Catch-22. If you don't have crawl space insulation, then there's no line of defense keeping humid summer air and cold winter air away from your floorboards. If you do have crawl space insulation, then moisture and mold can saturate the material, weighing it down and causing it to collapse on to the floor. If it's wet or lying on the ground, what can it do for your home?
The first step to solving a crawl space moisture problem is to remove any standing water issues. Left in your home, it will add humidity to the home, encourage mold and mildew, and bring pests into the room while it stagnates. It simply has to go.
If your crawl space has pooling water at any time, a reliable cast-iron crawl space sump pump is the best option. Water can be directed to the sump pump via a drainage swale, or in some cases, a modern French drain system.
Humidity pours into your house through the crawl space vents, and the damp earth and cement around your home will soak up water like a sponge, releasing water vapor into the area. Cut this problem off at the source by sealing off all crawl space vents and installing a crawl space vapor barrier. Avoid cheap solutions- the kind of product you're looking for should be strong and durable- at least 20 mil thick. A quality crawl space vapor barrier will allow access for you and service workers without tearing your line of defense. Crawl space vapor barriers should also be flexible and resistant to punctures and tears, and a bed of gravel should be laid underneath to allow water to pass underneath.
A Closed, Sealed Crawlspace - What a Really Bad Idea
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 Masters Specializes In Crawl Space Encapsulation in Bluegrass TN.