Crawl Space Moisture Damage

What Is A Crawl Space? Call 586-703-0112

A common place for leaks in foundations is at the bottoms of basement windows and the bottoms of the upstairs doors.
When a concrete basement wall is poured, the area where there will be windows or doorsills is blocked out. These window and door cutouts are always the same depth–about a foot below the top of the concrete wall. The windows and doorsills do not sit flat on the foundation wall. There is always a place on top of the wall and below the basement window that is on a bit of a bevel. You may notice this if you go down to the basement and look up at a basement window. Most of my customers look at the cut-outs in the wall and don’t realize there are actually two separate parts. We have the foundation wall, which is actually flat on top, and the part that the window sits on which is beveled. This bevel is adjusted by the carpenters and the bricklayers for the proper elevations.

The leak problem is actually caused by the area on the bevel below the window. The corners by these cut-outs are naturally places where the concrete is less strong to begin with, and the cut-out has mortar sitting on top of the foundation with a window or door frame sitting on top of that. When there is a layer of mortar sitting on top of a separate layer of concrete, a crack can happen due to the fact that the expansion coefficient between the concrete of the foundation wall and the mortar which holds the window, is just a little bit different. In other words, the two shrink and stretch in response to temperature changes at different rates. A split can form between the mortar and the cement because the two are not locked together, and eventually open, because nothing is holding them together.

Generally, a crack forms over a period of years.

This job on an office building was done like a window bottom. If outside dirt is high, we have to change things.

A crawl space is the area underneath the main floor of the house at an elevation roughly equal to the outside elevation. The word crawl space comes from the fact that usually there is barely enough space to crawl in this area. Most crawl spaces are 24 inches tall between the top of the dirt and the bottom of the floor joist. The size can vary from as small as 12 inches and as tall as 48 inches. At 48 inches or taller some people refer to this as a Michigan basement. Actually it is more like a small cellar than a basement. Above 6 feet, this space can definitely be called a basement. Crawl spaces can be fitted out to be equal to a basement no matter how tall the space is. Sometimes the furnace and water heater are in the crawlspace and sometimes the crawl space is waterproofed just like a real basement. We have installed concrete floors and insulation in crawl spaces.

Can there be mold and moisture problems in crawl spaces? There can be mold in unimproved crawl spaces. The mold in crawlspaces is usually the black mold as compared to the blue or green mold. Sometimes, if there is a high water table, or poorly draining soil there can be standing water in the crawl space on the dirt floor. We can take care of this right away using the standard waterproofing techniques of drain pipes and a sump pump, along with leveling the dirt floor. It is very important to clean out any junk on the dirt floor because this is the first thing that attracts mold and insects. This junk can also poke holes in the plastic vapor barrier that gets installed later.

Mold can grow on the wooden floor above the crawlspace area. Actually mold and insects can attack the subfloor above to the point where the subfloor weakens and can cave in. Sometimes the I-beam in the center which can be made out of wood can also be attacked by mold and insects. The I-beams are closer to the dirt, and are actually attacked first, becoming a real structural hazard. Insect and mold damage can spread all over the subfloor, and since the crawlspace is not a place that gets inspected frequently, gets missed by the owner, and gets to be an extreme condition. We have had to replace these wood I-beams in the past.

We at Oakbridge Waterproofing can repair structural damage, put in a drainage/waterproofing system, and put the moisture barrier in. Sometimes all a crawl space needs is a clean-out and a vapor barrier. Perhaps a dehumidifier would be
helpful. Other times a vapor barrier and waterproofing system is needed. The structural repairs that we talked about above are very rare and seldom tackled. For a homeowner, a good DIY job would be to clean out all the junk and get the crawl space back down to dirt. Another thing you could do would be to level the dirt off, to prevent having holes or low spots where water can collect and stay. Most water in a crawl space will sink back into the soil. The elevation in a crawl space should never be below the elevation of the dirt on the outside of the building. Never pile landscaping soil all around the foundation wall next to a crawl space, for this will cause an imbalance, and encourage water to sit in the crawl space at the points that are lower than the outside elevation.

Crawl spaces are based on common sense. The lower they are the more likely they are to collect water. The more junk down there made out of wood, the more likely you are to have wood-eating insects around. The more water you have down there, the longer it will take to evaporate or sink into the ground. The longer you wait to do something the worse the problems will get. I suggest you give Oakbridge Waterproofing a call. We can take a look at your space and tell you what we can do to get it into tiptop shape.call us at 586-703-0112

Author: Robert B McGuire