Standing water and ground water issue in a crawl space.
Challenge
One of our inspectors, Megan, was called out about some issues with a homeowner’s floor. There were three specific areas where the floor seemed “soft” or to be sagging. The homeowner had lived there for years and it seemed to be a pretty new development. They had redone some of the interior home and figured the additional weight of some of the new fixtures/appliances was the culprit. In the third area they figured the issue was that there were no support pillars in this area--it had been an addition to the original home. The homeowner planned on continuing to renovate areas of the home, and for that reason he wanted to make sure everything in the crawl space was set before continuing.
Megan had a gut instinct that it wasn’t the new appliances and interior work that had caused disruption to the floor. In Delaware (...and the areas of Maryland we service) most crawl spaces suffer from high humidity and/or groundwater issues. Consistently high levels of humidity and moisture can wreak havoc on organic materials (...like wood) when left unchecked. This wasn’t the first house Megan had been in that had “soft” floors.
The homeowner was looking for a quote from Megan to install a smart jack (support system for the floor joists to stabilize them) or to build some support pillars. As he showed her to the crawl space Megan noticed a temporary sump was in the crawl space to pump out some standing water. The homeowner explained that yes, the crawl space had standing water in it “a few times a year” but it wasn’t an issue because when he noticed it he would crawl under, drop in the sump and get the water out.
Upon further inspection Megan saw that a water line had stained the foundation walls in some areas and that water line was over a brick high. At the time of inspection, even with the temporary sump installed one area had over 6’’ of standing water. Continuing to inspect the crawl space she discovered a significant amount of microbial growth which indicated that humidity in the crawl space was consistently over 60%. On top of that she went though and tested the floor joists for a wood moisture content reading. Multiple areas were tested and the wood moisture content was between 18 and 26% on all the areas tested. On moving to the area where the majority of the soft floors existed it became clear that the wood supporting this area of the home was greatly compromised and showing early signs of rot.
Standing water and groundwater were evaporating into the air within the crawl space and increasing the humidity. As the humidity increased the water vapor wanted somewhere to go and was absorbed into the wood. Wood can contain some moisture but we are looking for it to be below 12%. Wood that has a content of 20% long-term will start to rot. Most homeowners don’t check their crawl spaces everyday so unless you know what to look for you might not realize that you (1) have groundwater and standing water issues, and (2) have high humidity.
By the end of Megan’s the homeowner was glad Megan was able to explain WHY this was happening. She also gave him a possible solution.
Solution
Fixing those troubled areas of the floor would be good, but long-term he would most likely continue to see the same thing happen in other areas of the home. We suggested installing an interior perimeter drainage system and a permanent sump pump. The drainage pipe around the perimeter will create a vacant space and water will look for the path of least resistance. Flowing into the pipe and draining into a sump with up to a 15’ discharge we will create a way to remove the groundwater/standing water as efficiently and effectively as possible. The first step to assessing the crawl area is always to address standing water and groundwater issues.
