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Internal and external foundation drainage to daylight

Dakota_G | Posted in General Questions on

I’ve been looking at various techniques for foundation drainage and have found an approach that I like for new construction (unvented crawlspace with 2-3″ concrete slab over foam insulation and vapor barrier, 4″ gravel base), but I cannot find a lot of information on this style. The image below is essentially what I’d like to go with: an exterior perimeter drain running to daylight with a pipe ran through the footer connected to the perimeter drain to relieve any hydro-static pressure from underneath the slab from rising ground water.

Does this method work well? With a daylight drain system?

Would this cause the perimeter drain to offload water under the slab if they are connected? Could you get around this by having the perimeter drain slightly lower than the footer pipe?

Thanks for any input.

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  1. Expert Member


    I have something similar on my own house. Because the foam and slab should both be above the level of your footing, you can place the inside pipe high enough that it joins the exterior one from the top. That way it can only back-flow if the drains are plugged.

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