The Crawl Space Concept

The Solution

Chances are very good that I have described some negative crawl space conditions in this article that you were not aware of. The good news is the solution is fairly simple. The hardest part is to allow your self the time to properly research the facts. When searching for information on the proper way to fix a crawl space you will certainly find a vast amount of conflicting ideas. The truth is out there and you will know it when you find it, it will be the one that makes the most sense.

Moisture Control

Before any of the negative conditions can be addressed properly the crawl space environment has to be controlled. We know moisture is a major problem with crawl spaces so let’s start there. When it comes to controlling any environment one has to know where the problems are coming from. So far we know the foundation vents, the open earth, the foundation walls and the cracks around the rim joist and foundation are the main source causing the negative crawl space conditions. Some franchise companies will want to sell what is called a vent cover to seal the open vents. On paper this product looks like it will work, and it does to some degree but it does not work as well as the alternative which is less expensive, a permanent solution and fairly easy to do. Most foundation vents are an 8” x 16” metal vent. A cement block is the same size and will fit into the opening once the vent and the excess mortar have been removed. To seal the block you have two choices; use a concrete sealant (caulk) around the block on the inside and outside of the crawl space or mix up some new mortar and fill the gaps around the block. Either way, the vent will be permanently closed and is in the same condition or better than the rest of the foundation. How you choose to close the vents will directly impact how much of a saving you will receive on your heating bills. The open vents are the number one vehicle for energy loss in the crawl space so be diligent here and don’t cut corners.

Once the foundation vents are closed it is time to address the open earth and the foundation walls. There are many different ways to address these two problems. If what you want is to completely eliminate these areas from causing any problems again in your lifetime then I suggest installing a heavy duty vapor barrier. There are some mixed reviews on how to install a vapor barrier in a crawl space and what products are recommended. Some “experts” will tell you that a 6 mil plastic will do just fine and in fact it will. But it will not last as long and is prone to tears and compromises that will get you right back to where you were when you started. Is it a temporary fix? Yes it is. It is also the minimum requirement for a crawl space floor. A better and a more permanent solution is to use a product designed for the problem like the DrySpace™ family of vapor barriers. The main differences between one vapor barrier to another is

going to be it’s durability, the perm rating (rate at which water will pass through) and the quality of the resin that was used to make the polyethylene. It is important to use a polyethylene barrier that is made from virgin resins, this will insure a long life for your investment. Most low cost polyethylene barriers are made from recycled plastic. While recycling is good for most products in the market place it is not good for this application because it puts your barrier closer to breaking down and becoming brittle. Any open seams, cracks or splits in the barrier will render even the highest quality barrier ineffective. Make sure you know what you are buying before you buy or you could end up with an overpriced knock off. Ask the supplier if there is a warranty for the longevity of the barrier they propose to sell you. If they are not confident enough to give a warranty then I would question the quality.

When hiring a professional to install any vapor barrier in a crawl space the majority of the cost is in labor, insurance and operating costs. So if you are going to pay $1500 for a temporary fix why would you not pay $2500 for a permanent one? Here’s my view; do it once and do it right. Even if you do it yourself don’t get caught up in the art of saving money, because in the end it will cost you more. Let’s face it, we don’t really know how long we will be living in a home. It could be three years or it could be thirty. If you plan a short term solution, you could own a long term problem.

Now that the crawl space environment can be controlled the next step is to dry it out. A quality dehumidifier is a wise investment if the home’s structure is saturated or the home is located in a high humidity location like Georgia. Here are some points to consider when choosing a dehumidifier. First, even before the price is considered, the dehumidifier has to be sized right for the area it will be controlling. This means, once the humidity levels are under control the dehumidifier should spend more time off than on. Most often a dehumidifier is viewed as working great because it runs all day everyday. The fact is it is not working at all. Look at it like this; if the dehumidifier is running all the time it can not get the humidity levels down to the setting on the control panel. What you have is a dehumidifier that is only helping to remove some moisture at the expense of your electric bill. A dehumidifier that uses 6 amps of electricity (about 700 watts) and runs 24 hours a day seven days a week will cost between $65- $80 a month in electricity. When the crawl space dehumidifi

er is sized properly it will sit quiet and only come on when the levels raise above the control panel settings. It will quickly reduce the moisture in the air and shut back down. No one wants to pay more for an appliance than they have too, but in the long run a cheap dehumidifier can cost much more in the electric bill in two years than the entire cost of a quality unit. On top of that, the dehumidifier that is size properly will actually keep the moisture at the desired levels.

Not all crawl spaces need a dehumidifier. It is our opinion that a crawl space which is conditioned with the air from the home is a better choice because there is a proper air exchange (which makes the air cleaner), the home is more efficient and it is more comfortable. This process is the hardest for people to understand and accept because of the current condition of the crawl space. Keep in mind the old environment is gone and it is now clean and dry.

Conditioned Air

There are a few components to accomplishing a conditioned crawl space successfully; conditioned air circulation and proper crawl space insulation. To understand the proper way to insulate the crawl space you should first know how and why to circulate the conditioned air into the crawl space. The benefits of conditioned air in the crawl space are; clean dry crawl space, warm floors, lower heating bills, cleaner air in the home and a more comfortable home. This is how it works. Air from the home, usually supplied by the furnace, is delivered to the crawl space as if it were any other part of the home. A source for return air is also installed to keep the crawl space from being pressurized. When the air that is delivered is heated, in the winter months, the object is not to heat the crawl space but to deliver heat to the home one level lower that it currently is. The advantage to doing this, since the vents are now closed, is the heat in the crawl space stays in the home. Heat naturally rises so it will, without other interference, pass through the floor and enter the living area. When the warm air passes through the floor it will leave the floor warm and comfortable. This alone will make the investment worth it. The heat continues to rise to the ceiling and on its way there it will help warm the living space that is occupied by the family. When the heat comes out of the registers on the main level it immediately heads to the ceiling without restriction. The lowest part of the room, the floor, gets the heat last because the heat must build up at the ceiling in order to be felt in the lower part of the home. With heat passing through the floors the home has a longer heat retention cycle than without it. In other words once the furnace is off and no other heat is being delivered to the room, the heat from the crawl space will continue to make its way up. This leaves the area in the home (below six feet), that our bodies occupy, warmer longer because the heat in the crawl space is restricted by the floor which slows down the rise to the ceiling. In turn this reduces the amount of heating cycles, the furnace runs less and the heat bills are lower.

During the summer months the efficiency works the complete opposite. During the winter the heat supply is the key vehicle for the efficiency while the air return supports the circulation of warm air to be exchanged. In the summer the air return is the key vehicle for the efficiency and the supply supports the circulation of cool air to be exchanged. Here is how it works, the earth stays about 55-60° F at about 48” (this is a medium guide and may very depending on location) during the summer months. With an air return in the crawl space the home can utilize this free cool air in the home. When the air conditioner (A/C) comes on its job is to take the air from the home, cool it and then redeliver it. In the process the A/C will also dehumidify the air. The air in the home is pulled to the A/C by way of the air returns and then delivers the new cool air through the supply. We all know or should know that the air in the crawl space is cooler than the air outside. When the air is pulled from the home to be cooled it will take the warm air from the ceiling area of the home and mix it with the cool air from the crawl space. Since cold absorbs heat the cool crawl space air will lessen the work load of the A/C. This causes the A/C to work shorter cycles and run less often which impacts the electric bill saving the homeowner money. On a quick side note – the best solution for the home is to have both a dehumidifier and conditioned air in the crawl space. Here’s why, in the high humid months of summer the crawl space dehumidifier will both protect the crawl space from high moisture and help the A/C run even more efficient. The dehumidifier will lower the amount of moisture in the home therefore allowing the A/C to cool the air quicker and that means running even less. During the spring and fall months the outside temperature may be at a comfortable level and there is no need for heat or A/C. In these months the humidity can still be a problem and a dehumidifier can insure the moisture levels in the crawl space are kept under control. If the budget does not allow for both, conditioned air and a dehumidifier then the best route is to condition the crawl space. You will gain the energy efficiency and the furnace will control the humidity in the winter because it will cook the moisture out of the air and in the summer the A/C will step up and dehumidify the crawl space air. The only threat in this situation is the weeks or months the crawl space does not have conditioned air because of the comfortable outside temperatures. One way to help this is to turn on the fan to your furnace (no heat no A/C) to circulate the air in your home and crawl space. The fan by itself draws very little electricity and is an efficient way to move air.

Properly Insulating the Crawl Space

Properly insulating the crawl space is very important to the energy efficiency of a conditioned crawl space. Insulation in the floor joists cavity is no longer needed if the crawl space is conditioned. Insulation in the floor joists would trap the heat in the crawl space and would only accomplish heating the crawl space. In order to allow the heat to pass through the floors they need to be kept open. There for the only place that insulation is needed is around the perimeter of the crawl space. The rim (band) joist is a critical area of heat loss because there is only 1 ½ inches of wood between the inside and the outside. This is also and area that will have small opening or cracks in the wood. I recommend R-19 or higher fiberglass insulation. Close cell spray foam insulation comes up often when discussing crawl space insulation. I do not believe this product is good for the crawl space. When it is sprayed it eliminates the ability to inspect the structure for water or insect damage and would make the repair very difficult and more expensive. When selling a home the spray foam can hinder a sale due to the inability to properly inspect the structure. I just don’t believe that the one advantage it has over fiberglass is worth the potential problems it could cause. Insulation on the foundation walls is going to be guided mainly by the local energy code of where the home is located. Every climate will have a different take on the requirement if foundation wall insulation. This information can be found fairly easily on the internet at any of the states websites or at the local building department.

Conclusion

There are different ways to fix the problems associated with open crawl spaces. The best way and the wrong way can simply be separated by a good sales pitch and the lack of research. This subject is far more complicated that just putting in plastic. Look at the crawl space as part of the home and treat it that way, like our society does with a basement. There are really very little differences between a crawl space and a basement, they are both under the home, they are both below grade and they both have problems with moisture yet we treat them completely different. Is ‘can I stand up in the space’ the only factor that decides if the space is worth fixing? Invest in your home and reap the benefits while your family is living there and regain the lost value in your home. I hope you found this article helpful and useful. If you have a minute give me a call and let me know if it helped you.

Best regards,

Matt Leech

877.379.7658

Compact Air Plus™