building a deck on a retaining wall, and other advice
I've got house on a sloped lot, it slopes down from the front yard toward the back.
The basement has a full-size door that walks out into an area underneath the back deck.
The walk out area under the deck is lower then the immediate surrounding area, ideally the sides should be built up a bit to keep water flowing away from the walk out, but the place hasn't been cared for in years, so currently they slope quite a bit into the walk out under the deck, as a result during heavy rainfall that area can get very saturated, particularly if the water table is high. The dirt level is only about an inch or two below the door sill, so that can lead to water flowing into the basement under the door! :( The water does get into the ground, so I'm sure it's just a matter of expanding the area and keeping the whole level lower then the door sill.
The deck itself is positively trashed and ready to fall down... I wouldn't be surprised if it's the original from 1950 when the house was built, it's /that/ bad.
Long story short, what I'd like to do is replace the deck with one that is about 50% larger, ideally I'd like to build 3 retaining walls so that I expand the walk out area under the deck and have the deck posts supported on the wall, like a foundation. On one side, probably either left or right, I'd have steps built into the retaining wall to lead from the yard to the walk out.
I'd like to lower the level of the "finished surface" in the walk out area by a couple of inches, so that it's about 3-4" below the current door sill plate. I'm thinking the "finished surface" would either be compacted gravel (2-3") or a highly permeable paver. That would give me about 5-7" from the bottom of the sill to dirt, so hopefully that will help resolve the water issue.
My questions are--
- Any thoughts on this plan, things I should look out for, or that I might be overlooking?
- Can a retaining wall be build such that is acts a support for the deck?
- Around here the footings for the deck must be 4' below grade, so that does mean that my footings need to be 4' below the level of the finished surface in the walk out?
- Would I just be better off having block wall (CMU) foundation walls built and then putting up some sort of a stone veneer and cap to make the visible parts more attractive?
I'm planning to have the excavation and wall down professionally, right now I'm trying to research what is best, what to watch out for, etc... I'll be working with a professional carpenter (friend) that I'm hiring to build the deck on top--I think that will be a "no brainer" once we have the retaining wall in place, I'm not looking for anything too fancy, just a typically rectangular deck. Of course I'd work my friend to plans together ahead of time to coordinate the location of supports for posts...
Forgive what an eyesore I have back there :), I'm hoping expanding the walk out will give me a better place to store the trash barrel, and I'm going to be building a shed to store the rest... I've also since repaired the bare spots on the lawn... as a I said, this place hasn't been cared for in years...
The sump pump discharge is another thing I need to figure what I can do with... the back of my lot is the low level for the neighborhood, so there's no way to bury the pipe and lead it elsewhere. My town has a storm sewer system, for an expensive fee I may be able to plumb it (and my gutters) into that.