Slab - Retaining Wall Questions...

[ndemge]

Got some good help from y'all on my slab question.<br /><br />Started plotting the site for the shed yesterday, and over the course of the 36' slab, I have about 4' off level.<br /><br />My ground is very rocky with clay, it does a great job of staying put with just grass cover.<br /><br />I'm will be splitting the difference between digging down and building a wall on the low side.<br /><br />On the side I did down, I will need about a 1-2' wall after grading. Can I do a cantaliver off the slab without a footing, just tie the wall into the slab? When I pour the slab, The slab will be thicker at the edge already. I would plan on backfilling this all with gravel.<br /><br />For the Downhill side, there is a pre-cast place p the road that makes these HUGE lego type blocks, $60 a piece, 5' long by about 2' thick and 3' tall. the quary uses them staked about 10 high with nothing tieing them together except gravity to hold gravel.

 

[Bondo]

Re: Slab - Retaining Wall Questions...

Can I do a cantaliver off the slab without a footing, just tie the wall into the slab? When I pour the slab, The slab will be thicker at the edge already. I would plan on backfilling this all with gravel.<br />

IF I'm reading this Right,.......<br /><br />No,.....<br /><br />The Wall, Should be Sitting On the floor, above the Footer at the Edge of the Floor.......

 

[magster65]

Re: Slab - Retaining Wall Questions...

I would not put a wall on a slab alone. The wall should be bearing on a footing. Building codes differ all over but here a bearing wall must sit on a foundation with a footing deep enough for at least 16" of fill to the bottom. They refer to the depth as frost protection.

 

[18rabbit]

Re: Slab - Retaining Wall Questions...

Prob with integrating a retaining wall into a concrete slab or foundation is the opportunity for moisture to wick thru the system. It is the perfect scenario for growing mold in walls, etc. This is why building codes now require foundations to top out several inches above ground level, to keep moist earth away from any entry point into the wall.<br /><br />If I remember correctly, you were planning a metal shed on that slab. Not likely to grow mold, but if you put any wood up against the inside metal walls, you are could be off and running with some wicked nasty mold.<br /><br />A 2-ft retailing wall is getting close to the max you can do without engineering the thing. You probably can install it w/o a permit or inspection. I would put the retaining wall designed with its own footing separate from the slab and if they abutted put a layer of b!tchathane (a.k.a. Bituthene) or equiv between the two concretes.

 

[ndemge]

Re: Slab - Retaining Wall Questions...

There is room, I could put the wall for the shed a few inches away from said wall.<br /><br />The reason I was going with a floating slab was to avoid the footer, but that's why I'm askin y'all, I ain't no engineer <br /><br /><br />So far, it looks like it needs to be a seperate beast..

 

[18rabbit]

Re: Slab - Retaining Wall Questions...

Keep in mind debris. If the wind blows leaves and stuff between the retaining wall and the shed, it could hold moisture against the metal, stuff like that. Maybe enough room to clean it out?!?

 

[Bob_VT]

Re: Slab - Retaining Wall Questions...

Noel you can get away with a floating slab (cap slab) where you live but it may crack and do wierd things being 36'. I would never build or place a cap slab over 24 at the most. You can save some headaches in the future if you either put in a footing or sink some 12 sonotubes about every 8 feet and sink them about 4 feet and attach to them. While your at it include a piece of drainage tubing in the gravel to give the moisture a fast path away from the slab.

 

[Colorado04]

Re: Slab - Retaining Wall Questions...

Noel,<br /><br />I used a slab on grad over undisturbed soil. It seems to be holding up fine. It's been a couple of years now. I too have a small retaining wall around half of the shed. The wall is along the entire right wall of the shed and back. There is at least 2' from the slab/shed wall and the retaining wall. I have put a small trench in the space between the two for drainage. All seems to be good so far. Been two years now.