Water issues. Regrading around foundation?

[Billbill84]

Hi all, quick question/concern.
There's a 2 good size low spots in my yard around the back corner of the house. It holds a lot of water close to the foundation during heavy rains and I've noticed some basement water seepage with flooding window wells. Two things I want to do are:
1) Raise grading up about 9" at the foundation wall then out out about 6ft and spread about 15ft wide on corner area and other problem side will be raised about 10" at the wall along its full length (20ft or so), and out 6ft then pretty much same under the deck after I rip it down.
2) Install French drain in this area after adding dirt.
My foundation wall is poured concrete. I was advised by two different building contractors to not add that much soil up to the foundation wall as they both said it's too much weight/pressure close to the wall and could easily damage it??? I immediately discredited both their claims after they said they would add sand instead of clay dirt. That obviously wouldn't shed water away from the foundation like clay soils would.
So are their claims crap? If so what's the best type of soil to do some heavy regrading in these low spots?? I'm thinking something with clay to shed water away and into the future French drain that will run along the sides of the house. House grade is almost perfectly flat on the sides with all the positive grade sloping front and back instead of all the way around the house. Any advice is appreciated. Thx

 

[Jeff Handy]

Yes, sand would be useless.
Just as heavy as dirt, and water runs right through it.

You also need to extend your window well higher, or have it dug out and replaced with a taller one.
Don’t expect covers to keep any flood waters out.

And you might need to raise up the a/c condenser onto a thicker pad, or raise the existing pad by laying it on a bed of solid concrete blocks.

 

[briananderson]

Sounds like a solid plan ... french drain done right will work wonders

 

[Billbill84]

Yes, sand would be useless.
Just as heavy as dirt, and water runs right through it.

You also need to extend your window well higher, or have it dug out and replaced with a taller one.
Don’t expect covers to keep any flood waters out.

And you might need to raise up the a/c condenser onto a thicker pad, or raise the existing pad by laying it on a bed of solid concrete blocks.

Yep thanks Jeff I was thinking the same thing about using sand. So stupid.
I already bought a couple new wells about 24" tall to replace them weak little 10" ones that flood from the bottom up due to poor grade.
About adding the clay soils, should I just lay the new soil directly over the grass or turn it all up first before regrading? Not sure if it matters because I'll have to reseed for new grass anyway in that large back corner area.
Worst case scenario, I could just skip any and all regrading and just do an open style French drain along the landscaping edge that wraps around the back corner.

 

[Steve123]

Code in just about any location requires the top of the foundation to be a minimum of 6" higher than grade. I'm not positive about the reasoning, but suppose its because there will be certain amount of splashing when it rains, and there will be a tendency to wet (and then possibly rot) the sill plate and/or siding. If you maintain at least this distance, you should be fine. Absolutely you can not put soil above the top height of the concrete foundation.

Having grade slope away from the house is always necessary (but not always sufficient) to ensure a dry basement.

I assume you have an exterior perimeter drain around your house at footing height. And possibly a sump pump. The proper way to drain a window well is with plastic hose down to your weeping tile.

 

[Jeff Handy]

No need to mix in the new top layer.

Just rake it smooth and grade by eye and with a long level.

As mentioned, do not go too high, or rot can occur.
Also, termites and carpenter ants can get into the framing.

 

[Billbill84]

Code in just about any location requires the top of the foundation to be a minimum of 6" higher than grade. I'm not positive about the reasoning, but suppose its because there will be certain amount of splashing when it rains, and there will be a tendency to wet (and then possibly rot) the sill plate and/or siding. If you maintain at least this distance, you should be fine. Absolutely you can not put soil above the top height of the concrete foundation.

Having grade slope away from the house is always necessary (but not always sufficient) to ensure a dry basement.

I assume you have an exterior perimeter drain around your house at footing height. And possibly a sump pump. The proper way to drain a window well is with plastic hose down to your weeping tile.


View attachment 25670

Thanks for the input Steve.
Yes I'm aware of the need to distance top of grade from the sill plate, luckily for me though my sill is pretty high up at least 14".
I'm hoping adding two French drains, one on side path from back of garage being an "open" French drain on side of house and Back corner, closed French drain, will move enough surface water down and away before the soils over saturate and flood the wells. If this works then I may not even need to add any soils.
The option to add window well drains is not possible because basement is fully finished and if the French drains do collect a lot of water from low grade spots last thing I'd wanna do is bring it inside and overwhelm my sump pit.
The open French drain will be in a current walk way around back going to be back filled fully with nice river rock. I don't really think I can add any grade here because the back garage door would have to be raised about 4-6" and now things are just making me want to pound that for sale sign in the front yard like the last fool that never disclosed any of these issues to us. Here's a couple more pics of my issue first 7 of side I can't raise without raising back door and utilities. Only thing I can think of is th open French drain. Pic 8 is the back corner I may be able to raise about 6" see how it slopes towards house? Last pic is why nothing can be done from inside of basement.

 

[Billbill84]

No need to mix in the new top layer.

Just rake it smooth and grade by eye and with a long level.

As mentioned, do not go too high, or rot can occur.
Also, termites and carpenter ants can get into the framing.

I'll try that thanks.

 

[BuzzLOL]

Code in just about any location requires the top of the foundation to be a minimum of 6" higher than grade.

That must not apply to houses built on a slab... also, brick, vinyl, and aluminum siding won't be affected by a little rain splashing...

 

[Steve123]

That must not apply to houses built on a slab... also, brick, vinyl, and aluminum siding won't be affected by a little rain splashing...

But how is your wet sill plate going to hold up ?

https://foundationhandbook.ornl.gov...ould also be,drainage is not always necessary.

 

[BuzzLOL]

But how is your wet sill plate going to hold up ?

Sill plate doesn't get wet if protected by siding, brick, stucco, etc.... and grade slopes away from building...

 

[tomtheelder2020]

Billbill, as a former engineering geologist I can tell you that preventing water from infiltrating is always better than collecting the water underground (if other considerations relatively equal). Always prefer an inlet to a closed pipe to a french drain. For a similar situation at my house I installed catch basins near the house and emitters near the sidewalk.
NDS 3 in. and 4 in. Combo Plastic Atrium Grate, Green-75U - The Home Depot
NDS 4 in. Plastic Pop-up Drainage Emitter-422G - The Home Depot

 

[68bucks]

That must not apply to houses built on a slab... also, brick, vinyl, and aluminum siding won't be affected by a little rain splashing...

I'm in NW Ohio and code here requires 8" of clearance between the siding and earth. That was when I built my shop a couple years ago.

 

[ajaynejr]

The ground up to the foundation needs to slope away and be of a consistency similar to that of the lawn further away. If you do not have enough height you can add at the foundation, then carve away from the maximum allowed grade sloping down gently anyway. At some point many feet away from the foundation stop the downslope and if needed slope gently up to the grade yet further away that has not been carved yet. This dip running more or less parallel to the foundation is an example of a swale. It should have a slope of its own to some low point away from the house where if needed you could install a dry well.

No specific French drain in the ground and above basement floor level is needed. Incidentally a swale is a degenerate form of a French drain, namely on instead of below the surface. Also, incidentally, had you gone with an underground French drain, that too would have needed a lead out pipe to some place away from the house to discharge the water. Said low point could well be where I suggested the dry well.

The dry well or other destination of the water must never back up to the house. Use emitters or sump pump or, if terrain permits, an overflow onto the surface out there.