For all those unsuspecting homeowners out there there is a growing problem being caused by nationally trusted franchise companies as well as small time contractors. The problem is sealing the crawlspace on a raised foundation in a pre-existing structures. This is almost always done without code compliance, and without correcting the source of the moisture problems at the exterior which led to the infiltration to the crawlspace prior to ever attempting. The outcome has not been good in the 3-4 years of seeing the end results in homes across 3/4 of NC counties. Speaking with other inspectors in this and other states the problems is not limited to NC and seems to be spreading rapidly, especially by the more nationally known and publicly trusted companies who were already at the home for legitimate work. Many times moisture related problems in the raised crawlspaces are easily identified and corrected if basic knowledge in building structure/design/function is understood. Such basic problems which can cause water infiltration into the crawlspace from the exterior are, but not limited to: lack of gutters connected to drain piping to extend the discharge at least ten feet from the base of the structure, downspouts that discharge near the base of the structure, poor site/soil grading which lacks at least a 1 inch drop per every foot leading from the base of the structure within the first 10 foot of the home, cracking/improper grading to concrete pads/patios, lack of waterproofing of the exterior of the foundation walls, lack of proper sealant at exterior penetrations/joints, and improperly positioned/directed sprinkler heads. Those are the first points of concentration to worry about before concerning yourself as to corrective measures within the inside of the crawlspace. When those areas are correct we can begin to address the inside of the crawlspace. Aside from the exterior being a source of moisture there is beneath the house also. Bare soil exposed beneath the home can many times cause elevated moisture levels to the air and wood framing. To reduce this occurrence a plastic vapor barrier of no less than 4-6 mil needs to be laid and secured to the soil with all joints overlapping by at least 12 inches. Of course any plumbing leakage into the area is detrimental and needs to be corrected immediately. Of further concern is any discharge/drain piping which terminates inside the crawlspace. Such lines can extend from HVAC evaporative units which should have been terminated at the exterior, as well as water heater pressure relief lines which should have terminated in the same room as the unit. Dryer or bathroom vent ducting terminating in the crawlspace can also allow warm moist air beneath the home and the dryer vent piping also deposits flammable lint. Improperly installed/restricted, and/or under insulated HVAC ducting can allow the formation of condensation on the exterior of the ducting which will further increase humidity/moisture levels. Many times having the foundation vents closed in the winter and open in the summer will cause unnecessary moisture levels. During the winter months, at least in areas of the states where I have been working in, it is noted that decreasing the moisture in the crawlspace can be helped by simply opening the foundation vents and letting mother nature help. However, in the summer months having the vents closed can be very detrimental. This can allow humidity levels to increase and moisture content of the wood framing to also increase. Many homes have fiberglass floor insulation beneath the floors and in the summer will be running conditioned air at temperatures which will decrease the temperatures of the sub-floor and floor framing beneath the conditioned rooms. Without the floor insulation the vents being closed may allow the point of condensation between warm/cool air mixing to occur at the foundation walls where damage would be minimal if the walls were insulated and sealed to the vapor barrier. With the floor insulation in place and the foundation vents closed the point of condensation between warm/cool air can all too often become the wood framing/sub flooring, and floor insulation. This can be to the point where the floor insulation is saturated to the touch and even to the point of becoming too weighted and falling from the installed locations.
Now were all the mentioned items above corrected prior to considering sealing the crawlspace? If not, the sources of the moisture which led to the thought of sealing the crawlspace were not addressed and we are doing about as much as attempting to place a bucket with a drain line in an attic below a roof leak rather than to correct the source of the leak on the roof.
The answer to the moisture in the crawlspace, many of these uneducated contractors guilty of improperly sealing these crawlspaces seem to believe, is the installation of a dehumidifier in the crawlspace, installing a vapor barrier on the soil, and sealing up the foundation vents. They almost never have corrected the issues which led to the moisture intrusion. If one is to control the air within a confined space very basic rules must not be forgotten. First is that to control the space we have to fully seal the space of all penetrations to prevent any external air entry into that space. Second is to control the moisture within the airspace which can be done with a dehumidifier. Third is to control temperature. If we do not have control of both temperature and humidity within that airspace dew point can occur. This can occur at normal 40% humidity setting on the dehumidifier. Say if the exterior air temperature is 93F and the humidity level is set at 40% in the crawlspace. With the interior conditioned spaces at 72-74 the insulated sub-floors/floor framing can easily reach 65F. At this point condensation can form on the exposed surfaces. This is why conditioned crawlspaces need a good control of conditioned air introduced into the crawlspace which will have no return ducting to the system. This is accomplished though the wisdom, education, experience, and calculations
Now with increased moisture in the confined crawlspace the chances increase of settled mold spores on HVAC systems, plumbing, electrical, wood framing etc. having enough moisture to germinate, colonize and reproduce. This can increase the likelihood of contaminating the interior air. If all HVAC joints were properly sealed and the system properly insulated, and if the penetrations where the HVAC ducting, electrical, plumbing, etc, extend into the crawlspace, from above were sealed this would reduce the chance of interior air contamination and further seal the crawlspace. (as would be required if done properly). Further concern is that there is now fungus/mold active on the exposed surfaces. These are living microscopic organisms which use enzymes to break down organic matter. Once thought that wood destroying fungus was the only fungus to be concerned with, research has led us to believe that many types of molds which were once thought of as common household molds and not wood decay promoting fungi can still bring the wood framing to a point of structural integrity loss by still feeding from the wood, just not always in the same manner as the typical dry rot fungi. Any contamination within the crawlspace needs to be thoroughly treated with an FDA approved fungicide for all porous, semi-porous, and non-porous materials as they all exist inside the crawlspace. This includes discarding the floor insulation prior to fungicidal applications. Without eliminating these organisms once discovered and sealing the crawlspace the true horrific nightmare begins. See a dehumidifier may reduce humidity in the air of that crawlspace thus reducing the moisture content of the wood framing. But starving a living fungus/mold which may have been surface matted on the wood framing of the vital air/surface moisture it needed to survive on the wood surface this can cause the fungi/mold root to draw the needed moisture from the wood framing bringing the wood to a point of dry rot without ever being at the industry recognized 28% moisture content that may promote wood destroying fungi. With the foundation vents open the fungal/mold off gas may be expelled to the exterior of the home, whereas when the crawlspace is sealed the off gas can find unsealed penetrations and/or pass through permeable floors to the interior of the home.
Much in the hazard line as the fungal/mold contamination problem is that sealing crawlspace in a pre-existing structure can also increase the chances of Radon gas levels increasing in the home and regular monitoring/testing is needed to reduce the chance of hazards associated with exposure.
All too often the installation of the dehumidifier requires additional electrical permits/work for the installation of a GFCI receptacle and breaker needed to provide power for the equipment.
Now with all of what was just stated above would you want someone to attempt this process of sealing the crawlspace in your home that doesn't understand these concerns, has no applicable licensing or permits as required for this work in the state of NC (and fairly sure elsewhere as well), and will charge you between 4-6K for this detrimental service, why are people falling for this and learing the hard way? Licensed pest exterminators who have just inspected the crawlspace for insects/moisture comes out and tells you that there is increased moisture content noted to the wood framing. Do they inspect the exterior and crawlspace for determination as to the sources of the increased moisture levels? Sadly, no. They pull out a nice brochure of a moisture control system which they will tell you is the only way to reduce moisture levels within the confined crawlspace. This again will be a 4-6k cost to the homeowner who doesn't realize that this doesn't correct the sources of the moisture, and will ultimately cause damage to the building materials due to the improper and partial implementing of a sealed crawlspace. The largest pest extermination companies in the world are now doing this mercilessly across the states. Terminix had just been caught doing this at a house last month in Fayetteville NC on Graham Rd. Their initial inspection report dated one year ago noted no fungus present, no standing water in the crawlspace, no cracking to the foundation walls, and moisture content of wood framing between 20-22% in areas of the crawlspace. Their answer was charging the client thousands for this crawlspace sealing of sorts. During a home inspection ordered by the home owner last month I find lack of gutters, poor site grading, condensate drain lines extending and terminating at foundation walls, unsealed holes drilled into the foundation walls for pest treatments left open after treatments and the foundation vents sealed shut. I find at the crawlspace entry door an unsealed, uninsulated access door of which I open to find standing water pooling i the crawlspace against the foundation wall at the low end of the house with no drain to allow an exit of this standing water, cracking to the foundation walls and I find openings left in the foundation wall where HVAC lines enter the crawlspace. Plastic vapor barrier has not been properly installed and has areas lacking a minimum of 12inch overlap at seams, and some seams not overlapped at all. There has been new GFCI receptacle, breaker, and romex installed in the crawlspace and a dehumidifier running within a few feet of the standing water. Visible fungus/mold is apparent in large areas of the framing beneath the house, and also inside the HVAC ducting and air handler unit installed in the crawlspace. When the homeowner contacted Terminix about these issues they sent the supervisor in charge of operations in NC and Sc as well as two of his workers. They crawled under the house seeing the disconnected ducting, the unsealed penetrations, uninsulated access door, standing water, mold contamination and the response was,"our system is functioning as intended and moisture readings of the wood framing are now at 10%. Now for 3 years I have been dealing with these guys on the phone and being hung upon and laughed at when I mention the detrimental harm they are causing. Furthermore they laugh when they are reminded that in the state of NC you are required to have applicable licensing and permits for performing certain trade work in homes. This instance may be a good example of why we have these requirements. LOL But again, here at Graham Rd, these guys are standing by their failed system. When the homeowner requested that Terminix provide proof of permits/licensing required to perform the work provided, days later the emailed response was an issuance of a refund and standing by their effort to control moisture in the crawlspace. The state licensing body who gives these guys a license for wood destroying insects don't care that their licensees are defrauding the public trust, knowingly and willingly breaking state code enforcement requirements, causing harmful growth of fungus/molds within the crawlspace, and decreasing the interior air quality of the home thus endangering the occupants of the home. Trust me, the state licensing division that grants Terminix contractors a license was at the house a couple of days ago and claims that they have no control over this. They don't care that there is now cracking to the foundation walls on the other side of the wall where standing/pooling water exists, and they don't care that electrical-vapor barrier-and crawlspace sealing has occurred with no proper permits or licensing. Their mission statement states otherwise, but they kept the "do nothing" stance saying that this would be a matter for the civil courts, licensing and code enforcement divisions and doesn't pertain to them. Now you can lose your license for committing a felony but not for defrauding the public out of thousands per client and knowingly causing detrimental harm to the building materials? With this posting will be the first public notice of this problem as newspapers, and tv news reporters never reply to calls/emails/letters. I will continue the crusade to stop this from occurring as the damage to the buildings and occupants over the last three years has been sickeningly vast. Without being able to reach the national media this is only caught and corrected on a singular basis. If the problem were to be televised nationally more victims would realize whey are victims and come forward, less people would fall prey to these malicious contractors, and a change would occur to the licensing requirements and regulations regarding the state divisions overseeing such licensing. BTW, this week they have been advertising that they now handle insulation! Also permits not followed in those instances as well!
So before you are talked into sealing up the crawlspace beneath your home please do the appropriate research in the steps/procedures necessary to do so, and make sure that your contractor is adequately educated, trained, licensed, and permitted to change the ventilation of your home. Check with state building code enforcement for necessary requirements.