Crawlspace Drainage and Flooding


My previous Crawlspace Inspection post covered the first two items from my Top Ten Winners list:

1. Cracked foundation / possible structural problems
2. Leaking foundation
3. Drainage problems / flooding crawlspace
4. Plumbing components issues – leaking water supply lines, drain pipes, crawlspace water heater installation problems
5. Heating system issues
6. Electrical components issues
7. Floor framing and structure support issues
8. Structural pest infestation – those are Termites, Powder Post Beetle, and Carpenter Ants
9. Mold problems
10. Crawlspace ventilation and insulation

Now, onto #3

3. Drainage Problems / Flooding crawlspace – What causes them: the water table mentioned in “Crawlspace Problems #1”, negative drainage around the house (soil / landscaping sloped towards the house instead of away from it), the top of the foundation below the soil level, and a malfunctioning or missing drainage system. Selling your house with such a condition could be a challenge, because standing water or even high moisture level attract insects, contribute to differential settling of the structure, and facilitate the growth of a variety of molds that can eventually promote unhealthy conditions.

The solutions aren’t cheep, but if you are trying to sell your property, fixing it might be your only option. So, let’s look at the problem, assuming that we’re willing to correct it:

– Soil / landscaping level should be always maintained below the foundation top. Otherwise, the water might seep inside between the foundation top and the wall base plate, brick, or whatever your walls are made of. Also, with frame houses, you can expect the base of the wall to start rotting and attracting a variety of insects.

– House surroundings should always be sloped away from the foundation to provide positive drainage / direct rain water away from the foundation and its footings.

If dealing with concrete surfaces that shifted over time and now are sloped towards the foundation, there are companies that offer concrete lifting, and this should be cheaper than replacing it.

– A flooded crawlspace with no installed drainage system and sump pump obviously requires one (high water table and negative drainage on exterior contribute to this scenario). The drain tile (perforated drainpipe) would have to be installed below the ground, and along the entire foundation footing (base), sloped properly towards the sump pump well, and located at the lowest point of the crawlspace (just to save you some digging). The ground water collected by the drain tile and deposited into the sump pump well would then be discharged to the house exterior (as far as possible from the house foundation).

– A malfunctioning drainage system might include a damaged or clogged sump pump, an undersized sump pump, a clogged drain tile, a negatively sloped drain tile (away from the sump pump well), and/or a missing drain tile. If you only have a sump pump well and pump installed – ground water is only being picked up from the area surrounding the pump well.

If you’ve newer examined your crawlspace but there’s a musty odor in your house (home owners often get used to it, so ask your visitors), or sometimes you might notice hardwood floor deformation – this might be a sign that your crawlspace needs some help …

Next winners from my list coming soon …

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