Personally, I'd look at a different piece of land. It's simply too dangerous to build IN a high water table and hope your sumps are going to work in all instances, like power outages, freezes, etc. So I'd either look for new land, or be prepared to build up and bring in a lot of fill.

Or do what we do in FL which is to build on a slab.

Avoid water. We are at the top of a hill, and when it rains steadily for several days, the water table rises (even up here) and tHe water seeps up through the basement floor. All the houses up here have sumps...and some have managed to finish the basements, but they are musty. Weather is getting wackier and if you have one flooding incident, it ruins your whole finished basement.

Are you in the process as in closing on the lot or have an offer?

A seasonal water table at 6.5' would make me very nervous if a basement was required. What happens during a wet year?

Depending on your area you may need to be a certain height above the water table as well.

we are supposed to close on the lot in ~3 weeks. Our builder is going to do a lot walk in about 2 weeks, I haven't been able to speak with the builder yet and get there thoughts as we just discovered this today.

We have high water tables here (not sure of the exact depth) and sumps are commonplace as are finished basements. I think that's completely foolhardy b/c even if your basement is dry the day you finish the house it's only a matter of time before it's not.

I'm insisting on a basement b/c we do occasionally get tornadoes, but we plan no living or finished space down there. My husband will have a shop with everything elevated. We'll have a sump and a backup. We'll waterproof as much as we can afford, but I know we'll get water or dampness eventually. And ripping out flooded carpets and drywall is not my idea of fun. ever.

So I suggest you think carefully about how you will use a basement and if this is not an acceptable way to live, then consider how to get out of the land deal.

Where in the country are you located? Do you need a basement? Can you do a crawl space or slab?

We are in Central OH - really just wanted the basement for storms and cheap extra sq footage

Slabs devalue a house here, because basements are the norm.

Nic,

Commercial buildings built in high water tables all the time. Residential - I would Avoid. How do you expect sump pit installed in water, pump could burn out removing water with the high water table from under the foundation slab. Raising foundation may be an option. Pour 5' stem walls and 4' wood framing above. This would allow nice daylight basement windows. I would never, eventually your foundation will develop a crack and water will leak. In addition to musty smell.

I know this is not what you want to hear but may be even drop basement height to 8'. Split 4' under ground and 4' above. Your frost like is 36", so you should be fine with 48" stem walls. Up up up and away from water.

Check on the master grading plan as well as there may be a set elevation for your house. Suggest checking into that as well.

We have a similar dilemma. Plans to build a nine foot basement with only one foot above ground level. The soil boring test came back with high seasonal water table at 100" (8'4"). Any ideas how we can make this work? Can we get an 8 ft ceiling with two feet above ground level?

If the only reason for a basement is severe weather--tornadoes--then forget the basement, build slab on grade and include in the design a "safe room" consisting of a poured in place and reinforced 8-inch walls and a similar roof slab. Make it large enough for the family to sleep at night using folding cots. Entry by a solid core door with proper hinges and latching. When not in use it makes a wonderful storage closet and it's always cool in there! And it's a lot cheaper than a basement.

Thank you for responding, Virgil. We actually need the basement for various living areas. The question we are dealing with is how high the house will have to be above the foundation to accommodate at least an eight foot ceiling.

My comment above was directed to Nic Rogers, who wrote, "...We are in Central OH - really just wanted the basement for storms and cheap extra sq footage..."

If your really don't need a basement, don't build it.

Birdie, you are taking a major risk for a wet basement sooner or later.

Our land has a high water table. Hit water at 4.5 feet. We live in the midwest and most homes have basements. Decided to forego the certainty of a wet basement and all that entails and built on a slab. Geothermal, radiant floor heat. Our main floor laundry room is also a storm room with 8 inch ICF walls and poured ceiling. I don't think I would consider a crawl space either as that would probably have moisture issues as well.

Thanks, Brian. That's what I was afraid of. We are at the end of our planning stage so this is pretty disturbing... My builder says the footings need to be two feet above the water table. The problem is we are trying to build as an addition to our old house- to make place for our elderly parents to move in. So if we can't align the two living spaces with a minimum of steps the whole plan is no good!

Coming from NJ where basements is the norm, I finally gave up on my dream of building a massive basement with 12' ceilings (for a couple of bowling lanes and more) due to a high water table at 3.5' in places. I also considered building the basement on grade however was finally dissuaded by DW and my builder. Tecnologically it is feasible to build a basement in a swimming pool however requires engineering, materials and cost, none of wich would add value to the home in PNW.

Our thinking for building a slab rather than a basement here in MN where basements are the norm. Having to disclose frequent water issues upon the eventual sale of the house would devalue the house far more than not having a basement!

We are going to do another soil boring and then decide what to do. Thanks for all the input!

Another soil boring will give you the water table on that day. Do some research on how often and how much the water table changes--especially in the flood of '03, or whenever!

It's not really a flood prone area. The 100" was seasonal high, based on the engineer's examination of the earth. So that would mean the highest level of the year is around that level.