The crawl space has an integral role towards a home’s overall value as well as the living space above. Most homeowners in Norcross Hills Chattanooga 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 Norcross Hills 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 Insulation and Its Benefits
There are three basic types of foundations in use today in the construction of a home.
A slab foundation is a foundation built directly on the soil with no basement or crawl space. Slab foundations are common in areas where soil conditions are not suitable for a basement, and are the most common foundation found in warmer areas such as Florida, Arizona, California and Texas, or anywhere where the depth between the soil and stable underlying rock is very shallow. Slabs are the quickest and cheapest foundation because they require less labor, skill and materials cost. They consist of a concrete slab that is typically 6 to 8 inches thick. Embedded within the slab is a grid of supporting ribbed metal rods known as "rebar." Even in locations where basements are prevalent, slab foundations are typically laid to serve as the base for structures like garages, pole barns, and sheds. Slabs are the least expensive of the three main foundation types but provide no storage or utility space, as the home actually sits directly on a large platform of solid concrete. Slabs have the disadvantage of being difficult and expensive to repair when they settle and crack, and plumbing lines that protrude from the soil upward through the concrete can also be expensive to repair. In areas where the underlying soil is thick or prone to excessive expansion and contraction, cables are embedded which can be tightened to provide better horizontal support and minimize the width of cracks.
Crawl Space (Pier and Beam) Foundations
A pier and beam foundation consists of either vertical wood or concrete columns (piers) that support beams or floor joists above the ground. The areas between the soil and the bottom of the house floor is known as the crawl space. These foundations are built either at ground level or over a shallow excavation that varies in depth, but is commonly about 36 to 40 inches deep. The best crawl space foundations have a load-bearing concrete perimeter wall and concrete or steel piers, both having footings below the freeze line of the soil, along with a good barrier over the soil to keep moisture under control. Less expensive versions have no load-bearing perimeter walls, piers with shallow footings, and no moisture barrier at all over the soil. Crawl spaces that enclosed by a wall or by skirting must have vents on every side to allow air to circulate and help keep the soil dry under the home. These vents must be configured to prevent the entry of rodents and snakes. Crawl space foundations are most often used in areas where there is heavy clay content in the soil that can severely damage (crack) slab foundations, or in waterfront or flood prone building sites where the necessary floor height to prevent water penetration of the living space must be higher than a slab can normally provide. The primary advantages of crawl space foundations are that plumbing lines are readily accessible for repairs, and foundation settlement problems are easier and less expensive to correct than with slab foundations. A primary disadvantage occurs when these foundations are not properly maintained or are constructed without adequate ventilation, allowing water or pests to cause damage. Crawl space foundations without adequate insulation applied to the bottom of the house floor can be very energy inefficient in a cold climate.
A basement is a type of foundation which includes an accessible space between the soil and the bottom of the first floor of a home. This foundation provides living space below the home, below the ground elevation. It is basically a slab foundation with walls and a floor. Basements are most often built in cold weather climates such as the Northeast, Midwest and Rocky Mountains, and in places where the cost of excavation is not prohibitive. Basements start with a hole approximately 8 feet deep, however, some homeowners will opt for a 9 or 10 foot deep basement wall to increase height and volume of useable space. The floor and walls are built, then the house itself is built over that. Basement foundations have the advantage of providing useful space for utilities, mechanicals systems, and storage not available in the previous two types of foundations. The primary disadvantage of basements is that because they are mostly below ground level, they are vulnerable to leakage, mold formation, and flooding. Basements in wet climates must always have a working drain and pump in the floor to combat flooding.
Crawl Space Encapsulation Systems DIY
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 Norcross Hills TN.