Foundation Drainage

[AJS]

Excavation Dilemma



My wife and I bought a building lot over 2 years ago, a 9 home subdivision about ½ a mile from LI Sound here in CT. We loved the area, wanted to build, and since land is hard to come by in this town we bought it prior to the road going in, and now we are at a crossroads on what to do with the foundation.



It turns out that the drainage for the footings, which are allowed to go into the storm drains in the road are not as deep as they should have been. When I put a tape in the

pipe that is for this use, it only goes down about 4 ½ from the current grade. Our plans

call for a minimum of foundation to be visible after the final grade is completed. With the depth only at 4 ½ deep my finished first floor height is going to be quite high. I do not have any other means to use for my drainage system other than what is already set.



3 other homes are completed in the development. 1 person elected to dig deeper and pump up to the drainage piping. A builder who was spec’ing a house (which sold for 609K)) elected to dig at the drainage height determined his depth to the storm drains.

He had way less than me, It is a nice house but it looks like it is on stilts. He is only 45-50

Feet from the road and minimal grade was brought in, he had 8 steps to get to the front door and 8 to get from the garage into the house. We want no part of that. The last person was so far set back he brought in 15K worth of fill to grade things up, and you can’t even tell his foundation walls were about 4 feet off the original grade. We’ll we will only be about 60 ft from the front, so we won’t be able to bring to much fill in to raise the final grade.



I really do not want the majority of my foundation exposed, even if I was to apply stone veneer, it still would like to elevated.



Sorry for the long briefing, but I was told that pumping up was not a good idea. Any thought out there on the matter

Thanks in Advance

[suemarkp]

Pumping it up isn't a good idea because the pump could fail (power outages also seem to come during heavy rain storms). I guess the key question is what are you doing with the foundation space -- will this be a finished basement, a semi finished basement, or a crawl space?

If its not a nice finished area and the water table is below where you want the foundation floor, then I'd dig it deeper and pump the water from the lower foundation drain to the pipes the builder already placed. After the house is built, you could evaluate what happens if you unplug the pump. If it stays dry after a week or two of heavy rains, you'll probably be OK if you want to finish it (but the floor may seep water after it eventually cracks). I'd also consider a waterproof membrane on the outside of the foundation.

If you want a nice finished basement, then you can still use the approach above but make sure you know where the water table is. If its high, that pump may be pumping a lot and I'd consider two (a backup/overflow pump) and I'd get a stand-by power source to keep them running when it rains. There will be more risk if you want a nice finished basement. Gravity drains rarely fail. A water prooof membrane may be good insurance too.

If this will be a crawl space, I don't know if I'd even worry about it -- let the foundation get and stay wet (just drain it at the 4.5' level instead of deeper).

[AJS]

Thanks Mark,

We are just planning on the using the basement for my workshop, storage,
general play for the kids, ie, those things we don't want up stairs, and problably some gym equipment. A couple across the street are digging this week, I am going to keep a close look at what they encounter, I have a soil
test from a test hole not that far from my lot, I talked to my neighbor this weekend who elected to dig deep and pump up, he said he only had dampness a couple of times since December, the pump took whatever water
that might have risen.

I like the look of having the least amount of foundation exposed, so I might look into using landscaping and retaining walls to tie my front yard.

Thanks Again