deck drainage/soil

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floatr

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I am replacing a old deck and have had issues with the water not draining out from under it well after a rain Its clay type soil..It is 15 inches above ground and facing a direction where the corner is that gets NO sunlight ever ,so that complicates the dry out much after a rain.It is in the southeast where its humid already so that only adds to the issue.
What are the best methods to use to prevent the high moisture or at least improve soil/drainage ?
I thought maybe slope it with a french drain at end but not sure about the water that goes into clay below deck.
Any other info is appreciated
 
It is always importand that the landscape slopes away from the house. I would reshape that and cover it with sheep poly and a couple inches of graver so water would just run out. Then if you still have a problem after the deck is built you can just do your drain around the perimeter.
 
Yes, make the soil even less porous and transfer the problem to someplace else that can handle it. A sump pump sort of does the same thing.

French drains have never worked for me but I've never done the calculations ahead of time. Lindeburg's books on taking the PE exam for civil engineering may help with this. My local library had a few of these books.
 
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Yes, make the soil even less porous and transfer the problem to someplace else that can handle it. A sump pump sort of does the same thing.

French drains have never worked for me but I've never done the calculations ahead of time. Lindeburg's books on taking the PE exam for civil engineering may help with this. My local library had a few of these books.

Do a simple perk test before attempting a french drain.
 
It's late so this may not be right -

A 12" dia hole, 12" deep has a dirt surface area of 452 + 113 = 565 sq. in. and can handle 2" of rain per hour. The hole is 113 sq. in. in area.

A 10' x 12' deck has a surface area of 17,280 sq. in. and so at this same rainfall rate would need a French Drain with a drain dirt surface area of 565x17280/113= 86400 sq. in.. For a cube shaped hole this is 44" on a side, roughly.
 
It's late so this may not be right -

A 12" dia hole, 12" deep has a dirt surface area of 452 + 113 = 565 sq. in. and can handle 2" of rain per hour. The hole is 113 sq. in. in area.

A 10' x 12' deck has a surface area of 17,280 sq. in. and so at this same rainfall rate would need a French Drain with a drain dirt surface area of 565x17280/113= 86400 sq. in.. For a cube shaped hole this is 44" on a side, roughly.

Convert that to to a ditch with perf pipe and gravel, more like a feild for a septic field.
 
It's late so this may not be right -

A 12" dia hole, 12" deep has a dirt surface area of 452 + 113 = 565 sq. in. and can handle 2" of rain per hour. The hole is 113 sq. in. in area.

A 10' x 12' deck has a surface area of 17,280 sq. in. and so at this same rainfall rate would need a French Drain with a drain dirt surface area of 565x17280/113= 86400 sq. in.. For a cube shaped hole this is 44" on a side, roughly.

I'm not disputing the math here (not qualified) but add this variable: the deck diverts some water and the ground underneath collects the rest.
 
I will try the perk test .Should i do it at the area closest to home ,or in both locations - including at what will be outer edge of deck?
thanks
 
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I would plan on trench some distance away from the house, any water you can keep away from the foundation is a plus.
 

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