mm wrote:


-snip-
So do you mean when the basement floor is higher than the ground
outside on at least one side of the house?

No. [though that would make life easy, wouldn't it?]

Otherwise, if you mean when the basement floor is lower than the dirt
but higher than the normal water table outside, one would have to have
a darn good check valve, to keep the water in the ground outside from
coming back into the house when it rains. Then the water table rises,
or even if the table doesn't rise, the trench or whatever would
collect dripping or descending water inside the earth.

No again. Your basement walls and floor should be sealed from water
infiltration. So they can be below the water table. That doesn't
always work, so drainage. I have an interior and an exterior
perimeter drain. They join outside, about 7-8 feet underground.
Then the drain travels about 40', with a 1/4" per foot pitch where it
meets the natural grade and sees 'daylight'.


I have a whole row or more of townhouse neighbors with basement
sliding glass doors leading right out to the back yard**. But for my
row, all the basements are entirely 6 feet below ground level.

But is any part of your property lower than your basement floor?
And if it is, how practical would it be to dig the trench and put in a
drain?

Jim