To French drain & sump crawlspace next to full basement or not?
In my Frankenstein of the house I have three basements. Original one from 30s (concrete foundations and floor – full height) in the center of the long house. Also on one side I have 70s basement, that I want to finish at some point, since it has more than enough head room.
Both 30s and 70s basements have a sump. 70s basement has perimeter footer French drain that drains into sump pit with two pumps. 30s basement does not have footer drain, just the sump with lots of holes in the liner.
New England got record-breaking amount of snow, which will melt and will likely end up giving me more headache than all this rain we got earlier last year, that made sump pumps work overtime. Both sumps were filling up real quick in the fall.
That all said, my big concern is now crawlspace. This is my 1st year in this house, so I never seen what damage melting snow does to this place. I am dealing with radon, so I am encapsulating the crawlspace properly. Here is my question:
Should I also do a French drain at the interior perimeter of the crawlspace draining into a dedicated sump pit? See the diagram of depths of each basement. Also, concrete foundation between crawlspace and 30s basement separates the two all the way to rim joist.
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Replies
Apollo,
This is a judgment call. If you have the time to wait, it might be best to see what happens in the crawl space between now and May.
If the soil in your region is porous, the sumps in your two basements (each of which is at a lower elevation than the proposed sump in your crawl space) should keep the water level low enough to keep your crawl space dry. But there are many factors affecting water entry into basements and crawl spaces. It's possible for melting snow and rain to enter your crawl space, even when the sump pumps in the adjacent basements are keeping these adjacent spaces dry -- especially if the exterior grade near your crawl space doesn't slope away from the foundation, or if your roof dumps water near the perimeter of your house. (If either of these problems exist, fix them when you get a chance.)
If you want to cover all your bases, install a sump in the crawl space. If you want to minimize your expenses, keep an eye on things for another few months before making your decision.