The crawl space has an integral role towards a home’s overall value as well as the living space above. Most homeowners in Clarksville Tennessee 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 crawl space waterproofing In Clarksville 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 Mythbusters
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 Vapor Barriers
First, it might be quite costly (several thousands of dollars). Second, and much more importantly, the sealing of a crawlspace is likely to degrade the IAQ (Indoor Air Quality) in your living space.
Rather than sealing a crawl space and creating an IAQ problem in the home's living space, there are less expensive methods to manage crawl space humidity. In the United States, the number of those with allergies is rising about 25% per decade, and asthma cases alone have doubled in the last 20 years.
The rise in those having allergies is more common in developed countries, and it is suggested there "must be something in modern, urban life that promotes allergy". Some studies indicate a direct link to the increase in air conditioning and tighter homes. People may save a hundred dollars per year in energy, yet spend thousands on medication and life style change, so, there is no question that the home's IAQ is, by far, the overriding, single most important issue.
Proponents of sealing and not ventilating a crawl space have stated , "venting a crawl space will either add moisture to, or remove moisture from, a crawlspace depending on the moisture content of the ventilation air compared to the desired conditions of the crawl space. Venting with dry air reduces the moisture levels in the crawl space, while venting with moist air contributes moisture". In this respect, such proponents are absolutely right-on correct!
So, even though it might cost a homeowner $6000-$8000, they suggest a closed, sealed crawl space because the possibility of venting with moist air can make the crawl space wetter.
An optimum alternative that might achieve the best outcome could be to ventilate the crawl space but with a ventilation strategy that would know how much water vapor is in the outdoor air and know how much water vapor is in the crawl space air. Armed with that knowledge the ventilator will be able to make an informed decision whether or not ventilation is going to be helpful or hurtful.
It is evident a strategy like this would permit a crawl space to be ventilated, to dilute and replace stagnant air, odors and gases such as radon, yet not bring in wetter air into the crawl space. A strategy like this will be more effective than other ventilation strategies (like a timer or dehumidistat) because it is selective about not bringing in wetter outdoor air, whereas the timer or dehumidistat is not selective.
Returning to the question of sealing the crawl space and using a dehumidifier to control moisture, there is no question that sealing a crawl space and using a sizable dehumidifier will reduce humidity in the crawl space, but, if sealing the crawl space can compromise the home's IAQ, you ought to reconsider.
1. Even if you are able to seal the crawl space well, you will need a sizable dehumidifier. It will need to be set well below a mold threshold limit because other surfaces may be colder. The lower setting is needed to prevent those colder surfaces from exceeding the mold threshold in the now stagnant crawl space.
2. A dehumidifier mentioned in article requires 30 times the power of other technologies.
3. A dehumidifier will need occasional maintenance.
4. When sealing walls and piers, how do you seal completely without creating a hidden path for termites? It means, of course, you can't completely seal it.
5: The crawl space has become a stagnant area, which, of course, is never cleaned, so odors and gases will be there and they will migrate into the living space of the home.
6: Under the vapor barrier it is always 100% relative humidity, so mold and bacteria is going to grow. And the mold and bacteria spores will migrate into the home.
With the home IAQ in mind, it becomes apparent that some sort of ventilation is needed in a crawl space. The ICC code for the usual passive ventilation setup required one sqft of opening for each 150 sqft of crawl space. Further, the ICC code stated that if a vapor barrier was installed over the ground surface only 10% of the venting area was required (ICC 1804.6.3.1). This would mean that only 1 sqft of opening would be needed for a 1500sqft of crawl space. Clearly this code wasn't working, so the ventilation rate was arbitrarily increased, and, now, today some state codes recognize the strategy of comparing inside/outside water vapor.
So, with IAQ being so important, we can define our goal in a crawl space project: remove/replace stagnant crawl space air and extract moisture from the wood mass in the crawl space. This makes a case for mechanical equipment.
Dilution and replacement of crawl space air with fresh, outdoor air is easily understood, but how do you extract moisture from the wood mass in the crawl space? You must reduce the vapor pressure at the surface of the wood, and you may do this by either of two ways. One is by dehumidification, another is to blow air across the wood's surface, better yet, blow drier air across the wood's surface.
So let's get down to the quick of things. From the home's IAQ perspective you should ventilate your crawl space, but using a dehumidifier and venting would be like setting a dehumidifier out on your front lawn, and then paying the electric bills.
A better system would use an intelligent mechanical ventilation system that, (1) keeps the crawl space closed during unfavorable conditions, (2) opens whenever the outdoor air water vapor content will lower humidity in the crawl space, (3) moves a lot of the lower humidity air to extract moisture from the wood mass. The result is, that as you are diluting & replacing stagnant odors & gases, and radon in the crawl space with fresh, outdoor air, you are also extracting moisture from the wood mass.
Further, an intelligent system might perform other functions, such as to not ventilate when it's freezing outside, and, if the crawl space gets too dry, the ventilator could also automatically reverse its strategy to pump moisture into the crawl space to further stabilize wood floors by maintaining the wood in an acceptable range.
There is one inexpensive, automatic ventilator with all the characteristics described above. It's called the Smartvent®.
Crawl Space Masters Specializes In Crawl Space Encapsulation in Clarksville TN.