Foundation Drainage

One of the first major projects that will need to be completed will be a foundation drainage system. As-purchased, the house had moisture in the crawlspace. For health and the longevity of the materials, I aim to make the crawlspace as dry as reasonably possible.

The drainage system will consist of a perimiter trench, drainage pipe (drain tile), gravel fill, and a sump pump and enclosure. I'm opting for a sump pump for this system to evacuate the water as opposed to a gravity draining system because there is not sufficient elevation change on the property to allow for gravity draining.

The first step is to dig a trench around the perimiter of the foundation. I'm trenching down to the level of the top of the footings. Some say, ideally, that drainage of this type should be beside the footing. I am electing, however, to run the drain tile on top of the footing for the following reasons:

• The soil around the footings will not be disturbed. I'm worried there could be issues with foundation movement if I start moving dirt adjacent to the footings.


• The footing will give me a level surface on which to lay the drain tile, ensuring no low spots. This will help ensure the longevity of the drainage system itself, as it should be able to sufficiently drain the water admitted to it and dry out between wet spells.


• I've elected to dig by hand...and to dig deeper than the top of the fitting would mean more work!


• This is a crawlspace, not a basement, so I'm not worried about water getting to the level of the footings...I just want to keep from having to crawl around in mud to fix things!

I had planned to rent an excavator or trencher to perform the work. However, I did need to get out the shovel to determine how deep my footings actually were. When I got to work with the shovel, I realized that the soil around the house is REALLY easy to dig and in about an hour I had roughly 1/4 of the perimiter of the house dug, more-or-less, to the footings. So, I get to save some money and work a few pounds off. I did manage to break my shovel...but that won't stop me for long.

I should have more reports of progress on the drainage system as it comes along. I need to dig the pump pit, ad an enclosure, finish the trenches, install drain tile, backfill with gravel, and on and on. It's going to take a while!

A note about where the water goes: Ideally, rainwater will be handled on the property, reducing its contribution to water quality problems due to excessive runnoff. The system I'm putting into place as described above is meant as a "fail safe" or "last effort" plan to keep the crawlspace dry and the foundation stable, particularly while I'm goign to be doing so much work in the crawlspace. It will discharge to the street, travel into stormwater drains, and ultimately find its way into local streams and rivers. Future considerations for landscaping will try to minimize the water that gets to the foundation in the first place, and also limit the amount of runoff.