This is my first post on this forum, but I’ve gleaned a lot of information by simply lurking around for the past few months.
My question deals with how low I can site my house on our lot without running into water problems. The soil is sandy but the water table is quite high (2.5 feet below ground level during the wet weeks of spring. The lot slopes down toward the back and there is an established drainage ditch near the site that slopes downhill to a pond about 400 yards away.
Can I place my footings at (or possibly even slightly below) the level of the seasonal high water table as long as I can still get a drainage pipe sloping away from the foundation to daylight in the drainage ditch? I want to sight the house as low as possible to eliminate unnecessary fill, but I don’t want to risk a wet basement. We plan on tiling both inside and out and my thinking is that even if the water table would rise, it would simply drain through the tiling and pipe to the open drainage ditch.
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The pros here (and this DIYr) are going to want to know climate, size of house, type of walls, whether there are other house built near-by that you can use as reference points, and probably more. Quickest way to get the best answers is to include as many details as you possibly can in your early posts.
IMHO, best way to mitigate any risk is to look at other construction in the area before you start digging.
The home will be built in southwest Michigan so it is a cold climate. The walls will be poured concrete. The basement size is about 1300 square feet with the total square footage of the house being 2200 (not including the basement). There are houses nearby, but their elevations vary quite a bit.
Great...then you can be a nice future nieghbor, and ask around about wet basements (or dry basements in spite of the high water table) and find out what techniques/elevations they used and who thier contractors were. That's where I would start.
The answer is yes, it can be done - putting footings below the seasonal water table, but it is not the greatest thing to do and can add to cost and danger of work.
Excavating deeper in wetter ground means enlarging the hole so that if walls cave in, no-one will be buried or work destroyed. That larger hole will be more expensive.
The footings will still need to be on firm ground. You may need to dig a foot or so deeper and then compact crushed stone into the fill back before footings. The perimeter drain line should be laid at the base and installed carefully because that is your primary line of defense against the water.
I understand that you have aesthetic concerns but keep this in mind, over time, the house may settle in an inch or two and you will no doubt add more soil than you think for flower beds, etc. You definitely want to be able to slope surface drainage away from the house. Now is the time to solve all of these problems you might have, not after you have a foot of water in the basement so install a sump pump too and place the house elevation eight inches higher than you think you want it.
You may also need a grid drain under the floor in gravel to pick up the rising ground water from underneath.
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Excellence is its own reward!
Edited 5/1/2003 8:49:06 PM ET by piffin
A couple years back, new construction, hit water during excavation. Home happened to be partially earth bermed. So while were building and planning, I kept mentioning water proofing the foundation, drain tile, etc. My friend, who's helping me, and his own basement is a leaker, keeps telling me, "No Jim, we are building a boat, and there will be no leaks, for once it leaves this ship yard, it's otta of our hands, were building a boat, no leaks, can't have no leaks, building a boat. Best of luck Jim J