Why Now? #1
The Crawl Space Concept
Written by Matt Leech
President/CEO of CrawlSpace Concepts LLC
March 18, 2009
I get phone calls from homeowners that live all over the U.S. and Canada asking me about the closed or conditioned crawl space. No one seems to wonder if it will work but rather how it works. If we look back to the 30’s and 40’s there was no such thing as a conditioned crawl space. Yet today, as some crawl space companies put it, you can die if you don’t have it done their way and right away. So how did we live without it back then? Well, the answer is much more complicated than the question. Looking back to the early part of the last century there were many things that we had never heard of like plasma televisions or a laptop computer. But that did not stop the technology and research from making it possible. The conditioned crawl space concept is no different. In the 30’s and 40’s we had a different lifestyle, the windows were open in the summer and there was no air conditioning. The homes were built with different technology and guidelines so they were not as air tight as they are today. In fact many of the homes that were built in this era have added air conditioning and have been improved and updated to today’s standards for energy conservation. This is a good thing but it also means that these homes get less fresh air than they use to. By tightening up these homes they have confined the occupants to the environment created inside the homes envelope. As environmentalist study the causes of pollution in the air outside and make headway to improve and control the emissions given off by factories and vehicles, there is very little push to improve the air in a families home. Even the indoor air in public buildings is a strong focus today with banning cigarette smoking in cities and states across the country. Yet there are no guidelines for healthy air inside a private home. It is up to the families to identify and correct this problem. It is known, however, that the air inside an average home is seven times more polluted than the air outside and up to twenty times more polluted during the winter months. How can this be? It simply comes down to the lifestyle of the occupants and the environment in which the home was constructed. In this article I will be more focused on the latter of the two but more specifically homes that are built on a crawl space.
The Crawl Space Environment #2
The crawl space environment is no different than that of a cave in the side of a mountain. It’s dark, dirty, and smelly and has small animals and bugs living in it. When the home was first built the crawl space was not considered part of the house. Excess building materials and waste was thrown down there because it was easier than picking it up and discarding it in the dumpster. I have personally taken out old refrigerator doors, tires, old pipes, a toilet with the seat and drop ceiling panels among other things. It is also not uncommon to remove the carcass of a dead animal or two. This is the condition before anyone tries to improve it. Back in the day it was required to have vents in the foundation to promote cross ventilation in order to help control the moisture that would escape from the ground. This caused a few other problems, cold air getting under the home and making the floors cold, allowing even more moisture to get in by way of the humid summer air and a constant supply of mold, mildew and fungus spores. The cold floors were addressed by installing fiberglass insulation in the floor joist cavity and the other two problems were thought to be unavoidable. Now we have a dark, dirty, smelly place that has small animals and bugs (powder post beetles, termites, creepy looking bugs about 1 ½ inches with long furry legs that run faster than my eleven year old son) living in it, we add more moisture via the vents and plenty of mildew, mold and fungus seeds. The next thing we do is add a fiberglass nesting material for the animals to bed in and then through the open vents in the foundation we make it cold enough in the winter to raise the heat bill and chase these small animals and bugs into the home in search of food and a warmer place to live. By spring, a few mouse traps and a can of ant spray the home is ready to start this cycle over again. This is a reality for most crawl spaces so it is no wonder nobody wants to go down there.
Did I mention that crawl spaces are prone to flooding? #3
We all know that water runs down hill, with that being said crawl spaces are generally lower than the ground around the home because we backfill the foundation so that water shed will run away from the home. Over the years the backfill settles to a negative grade and allows water to rest against the foundation of the home. So when it rains hard in the spring and fall the ground becomes saturated. Once the ground will not take on anymore water it begins to run to the lower lying areas like ditches, storm drains and crawl spaces. Once standing water is introduced into the crawl space the homeowner runs the risk of major foundation failure and joist and beam rot. The major reason the standing water can be so devastating is because it goes unnoticed for long periods of time. The homeowner may periodically look in the crawl space for water or the source of an odor and not see any water. That does not mean in the last six months while the crawl space went un-inspected water did not come and go several times. Keep in mind the conditions described in the last paragraph and now add scum and rodent feces floating on top of the water inside the crawl space. It becomes extremely hard to reason that the old way of maintaining a crawl space is working just fine.
False water table, what’s that? #4
A false water table can be the culprit of why your crawl space keeps getting water in it no matter how waterproofed the foundation is. A false water table is the retention of excess water by none virgin soil. That means when a home is built there is a hole dug in the ground for the foundation, whether a basement or crawl space. After the foundation is in the dirt is filled back in around the outside of the foundation walls, this is called backfill. The backfilled dirt is not as compact as the undisturbed virgin soil that surrounds it; ultimately the backfill holds more water. The water in the backfill sets against the foundation and the virgin soil. Water will find its own level, so as the pressure builds around the foundation it naturally starts to spread itself out. If you picture a bowl that is 6” deep with 3” of water in it, the water is not on one side or only at the edges. It is evenly distributed across the entire bowl. As long as water is poured into the bowl the water will keep rising toward the top. This is what happens around the home and that is why it is critical to have the proper elements in place to protect your foundation. The virgin soil and evaporation will slowly reduce the water levels around the foundation but meanwhile the concrete foundation takes a beating.
I think it’s time to take a look at the research #5
Is this where it gets complicated? No, its common sense really, it’s just too bad that it took so long to be common. In order to figure out the solution, one has to first identify the problem. So what is the real problem? Is it the standing water or the bugs? Maybe it’s the vents or is it the smell? The answer lye’s with what’s common with all of these symptoms. I’m not trying to confuse you with riddles, I want you to see that what seems like the problems are only symptoms and if you only address the symptoms you will not fix the problem. Lets take the bugs for example, to many people go to the grocery store and buy those bug bombs and let them off in the crawl space thinking “that’ll fix ‘em”. Well it probably does but they also just let off a half dozen cans of poison in their home. One home I inspected had Stick-Ups on the heat ducts to help the smell, it didn’t work though. If you pump the water out it will just come back, if you seal off your vents the moisture from the dirt will be trapped inside the home. If you only address each symptom you will get either a new semi full time hobby, make the other symptoms worse or actually create new problems. What all of these symptoms have in common is crawl space moisture or humidity. Insects, wood rot, mold, fungus, mildew, odor, cold floors and high heating cost are all the result of attempts or the byproduct of the attempt to control moisture. Now that we know this and agree that moisture is the problem we can now properly address it.
Four Ways Moisture Enters The Crawl Space #6
The First Way
There are four main ways that moisture enters a common crawl space. The first and most obvious way is through the open dirt. As the ground outside the home is saturate with rain, the moisture level in a crawl space raises rapidly. The warmer the air, the more moisture it can hold. This means the most devastating months are the warm ones. This excess moisture condensates to cooler surfaces like water lines and the foundation walls. It also settles on the ground when the temperature falls, gets absorbed by the wood structure and any insulation that is installed in the crawl space. The building code in nearly every area of the country requires a vapor retarder with a perm rating of less that 1 to be installed on the floor of the crawl space. There are no requirements to how it should be installed, just that it must be. This leaves a wide gap in the final performance of a vapor retarder. If anyone wants to find recommendations on how to install; there are many opinions on the internet. It is not really a mystery if you know what it is suppose to do. For the sake of conversation, let’s say we go down to the local hardware and buy some plastic and install it in the crawl space according to the local building code. The problem of moisture entering the crawl space from the ground is fixed! Right? Well not entirely, any gaps in the plastic (at the seams, around supports and where it meets the wall) will still allow moisture to escape. It will continue to allow this to happen until the air, the wood structure and the concrete foundation are saturated. To make it more complicated, when the temperature falls in the evening the excess moisture leaves the air and settles like dew on top of the plastic only to evaporate again when the warmer air returns. Then the next time your plumber has to go down there to fix a frozen water line the plastic will probably not be in the same place as it was when you installed it causing your efforts to be wasted. The other common issue is when the crawl space floods, water gets on top of the plastic and can not be absorbed by the earth. This of course leaves a breading ground for bacteria and mosquitoes while introducing a new long lasting supply of moisture.
The Second Way #7
The second way moisture gets in the crawl space is through the open foundation vents. This is a huge area of confusion and there is a lot of very technical information out there on how the foundation vents impact the crawl space. You will read about relative humidity and vapor pressure. How the high and low pressure weather fronts impact the crawl space and how the vents being open or closed makes no difference. You will also read how the temperature affects these different technical conditions. On a quick side note, when the reports say it makes no difference if the vents are open or closed, they are referring to manually sliding the vent to the closed position. If you’re like me you will read these reports a few times just to feel comfortable with what it is saying. Some of the research is bent and formed to justify their own product line they want to sell you. I will give you a good example; the article titled “CRAWL SPACE MOISTURE CONTROL – A Fundamental Misunderstanding” written by Peter Carpenter explains, in quite a bit of detail, why you need mechanical ventilation to the outdoors in order to control moisture in the crawl space. To me this theory is more based on selling a product line than correcting a problem. The bottom line of the article is to install foundation vents with electric fans in them which are controlled by a humidistat. By doing this, the idea is the fans in the vents will come on when the humidity near the vent rises past a desirable level. Essentially the fans are meant to keep the warm moist air out by turning on when the outside moisture levels rise. Think of a vertical wind tunnel with a fan at the bottom and a balloon falling down the tunnel toward the fan. Each time the balloon gets close to the fan it will turn on and blow the balloon away. This theory has solid standing IF the crawl space vents were an absolute requirement. It is, in my opinion, a compromise between actually fixing the problem and doing nothing. If you read between the lines the article clearly states that the problem is the foundation vents allowing moist outside air to enter the crawl space. Their solution is to create a negative pressure in the crawl space, (take air from the home, pull it into the crawl space and then discharge it outdoors) in order to actively keep the moisture at bay using the same vehicle that causes the problem in the first place. It is my own deduction that the air is pulled from the home; there is no other obvious source of air that will replace the air being blown out of the crawl space by the electric fans. This theory is put into practice by Humidex, E-Z Breathe and other power ventilation manufactures. Here are the flaws to this theory as I see it; the process they describe works against the natural air flow of the home (which is up not down), it does not address the other conditions in a crawl space such as odor (when the fan is off), condensation, air quality, energy loss, cold floors or frozen water lines. Like I said it is a compromise, and it only attempts to address one source of moisture. It also potentially increases the energy loss in your home by pumping your conditioned (heat or cooled) air into the crawl space and then outside.
The hot topic is whether a homeowner can close the foundation vents in the crawl space. Not just sliding the vent closed but completely removing any way for air to move into the crawl space from the outdoors all year long. In other words permanently close the vents. You can find the answers in the International Residential Code – 2006 IRC 408.3 and subsections. Like any subject, to find the correct answer you have to ask the question correctly. If someone asked “do I need my vents?” the answers would range greatly. Some would say yes, some no and some would need more information. If you asked “do I need ventilation in my crawl space” you would likely get the same mixture of answers. The two questions are, however, completely different and with different answers. Like any new ideas there is going to be a clash of correct and incorrect answers. Most of the incorrect answers will be a result of ignorance on this subject; ignorance is defined as a lack of knowledge. While our own lack of knowledge brings us to asking the question, we find the blind leading the blind. My intention is not to be critical, but to encourage everyone to do their own research. If you’re not sure where to start I would be glad to point you in the right direction.
The Third & Fourth Way #8
The third way moisture enters the crawl space is through the foundation wall. Concrete block foundations have a much bigger problem with this than a poured concrete foundation wall. Concrete block has two hollow cores in each block. These hollow cores have a history of filling with water as the ground get saturated during a rain, by leaving the garden hose on or by a leaking hose bib. The concrete block is very porous and will allow water to pass through it. Once in the core of the block the water will level out until it finds a compromise in a motor joint or in the block itself. At this point the water moves freely into the crawl space. If the water does not find a compromise it will slowly migrate through the block to the driest side of the foundation; either back into the dirt outside or into the air of the crawl space. Since the water came in from the outside it is not likely that it will return there unless the ground dries out extremely fast. With a poured wall foundation the weaknesses are poorly patched rod holes and foundation cracks. Both of these issues will allow water to move freely into the crawl space. If the home has a problem with a false water table the water in the crawl space can also come up through the dirt floor.
The fourth way moisture enters the crawl space is by way of small cracks that are located where the wood structure meets the foundation. This is not as serious as the other three but worth mentioning. The rim joist and sill plate should be inspected for large gaps and poor workmanship. The issues in this area are generally easy to correct.
Crawl Space Ventilation; Yes You Still Need It! #9
Crawl space ventilation is the most critical part of handling the crawl space moisture problem. It is not the only part, but the one that will affect the quality of air that is in your home. You have to get this part right or the current situation will likely worsen. A home, a cottage or any building that is closed up without air circulation will smell stale. It is not an uncommon practice to “air out” a summer cottage that has been closed up for the winter. The process of airing out is simply circulating the air inside the cottage; exchanging the old stale air with new fresh air. The more air that is exchanged the fresher the smell. This air exchange is also required for a crawl space. Really, that is what the foundation vents are supposed to do. When you look at the current condition of the crawl space, most often it will need a steady supply of fresh air. We already went through the negative issues with exchanging the crawl space air with the outdoor air. So, how does the crawl space get fresh air if bringing in outside air is bad? First, I want to make sure my view on this subject is clear. I am a huge advocate of bringing in fresh air from the outside into the home. Open the windows when the temperature is comfortable, air out your home regularly. Fresh outdoor air is great for your health. How does this help or hurt the conditions in the crawl space. Well, the most important thing you can do to properly assess and make good decisions about air exchanges in your home is to stop separating your home into different parts when you are considering an air circulation plan. Since the time your home was built the crawl space was not considered part of the home, its time to change that! Whether you like it or not a large amount of the air in the crawl space makes its way into your home. Every tactic we have used in the past has failed to impact this particular problem. The odor you smell, the condensation on the windows and the allergy symptoms all remind us that there is something going on in the crawl space. Simply put, we experience at least some of the conditions from the crawl space inside our home. The more serious the condition the more motivated we are to getting it fixed. Living with the more serious condition from the crawl space making its way into the home, the last thing anyone wants is to circulate that air freely into the home. That would make it much, much worse. Right?! This probably is the most successful “pitch” the companies that sell the mechanical vents can use. Their mantra can be “don’t let the crawl space air into your home”. If the goal is to allow the crawl space to exist as is, then of course that would be a good plan, provided you are willing to use the conditioned air in your home that you paid for to fuel the plan and are willing to accept the other flaws. There is a better way, I want to give you some more information first so that you fully understand the decision you are making.
Natural Air Flow In a Home #10
The natural air flow of any home is up. Air is pulled from the lowest level and introduced throughout the home. The vehicle for this flow is heat. Of course everyone that graduated middle school knows that heat rises and cold falls. As the heat rises it is replaced by cooler air, this is what creates the natural air flow of the home. Whether you are heating the home in the winter or fighting it off in the summer the heat will always dictate the circulation direction. The natural air flow, also called the stack effect, will continue to move the air in your home toward the roof unless you allocate sufficient resources to change it. In my opinion, using mechanical vents to change this natural condition is an attempt to reinvent the wheel. It will not stop the warm air from rising, it is not a sufficient resource to change the natural air flow in the home and it will leave the homeowner with a failed concept that was backed by a great sales pitch, while still owning the problem. Granted the problems will be lessened and less frequent but nonetheless – not extinct.
Cold Floors, Energy Loss & Crawl Space Insulation #11
This is another huge topic throughout the United States and Canada. Cold floors and energy loss are directly related to properly insulating your home and the crawl space. However, insulation alone is not the answer. Here is what I tell my customers that call me for advice and to help them understand the problem of cold floors and heat loss. If you build a shed in the back yard and insulate the walls, floor and ceiling with, let’s say R-30 and the outside temperature is 0 degrees. Is the shed warm or cold? The answers I get are split – 40% say warm and the other 60% say cold. For the 40% that say warm, I help them understand why their answer is incorrect. Insulation does not make a shed or home for that matter warm, heat does. The job of the insulation is to retain the heat. Of the 60% that answered correctly I only have to ask one more question; what would make it warm? This follow up question definitely exposes the ones that guessed but nonetheless they understand what the missing link to their problem is. If you take the heat source out of a bedroom and closed the door, that bedroom would be cold. It is no different with the crawl space, but with a crawl space the home will usually have open vents. Even if the vents in the foundation are mechanically closed it will make little difference in the temperature of the crawl space. My analogy for this- would you install those same vents in the walls of your living area and expect them to hold out the cold if you closed them? Of course not, that is not part of there design. The other part of this equation is the characteristics of warm and cold air. Heat rises and cold falls, this fact directly works against keeping the floors warm in the winter. As the home is heated the warm air rises to the ceiling where it is picked up by the return air ducts (in most homes) and sent back to the furnace to be reheated and delivered again. Once the heat is delivered to the living area of the home and the heat begins to rise (away from the floor) colder air replaces it at the floor. So once the cycle of rising warm air starts your floors get the cold air. Now add to this the fact that the crawl space (just inches below your feet) has no heat source and is much colder than the living area. We must now recognize two other characteristic of cold to fully understand the impact; cold absorbs heat and the lack of heat is cold (not the other way around). This is a major disadvantage to heating a home and the only reason the furnace has to continually work to warm the home during the winter months. Floors over a basement do not have these cold floor problems and that is because the basement is heated. The insulation in the crawl space ceiling does little to protect the floors from the heat absorbing cold. However if you took the insulation out and left the crawl space as is, your floors would be even colder. There is a fix to all of these problems and it is probably less expensive than you may think.
The Crawl Space Solution- #12
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.
Crawl Space Moisture Control #13
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 conditions and high crawl space moisture. 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.
The Open Earth #14
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 SilverBack™ family of vapor barriers. The main differences between one crawl space 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.
The Art of Saving Money #15
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.
Dry the Crawl Space #16
Now that the crawl space environment can be controlled the next step is to dry it out. A quality crawl space 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 crawl space 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 or more in electricity. When the crawl space dehumidifier 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 in the Crawl Space #17
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 into the house. 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.
How It Works #18
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 #19
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.
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 is 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.