Foundation Thickness and Form

[mstang1988]

Ok, I think I'm finally going to start the oven! Plans have been done for a while and just need to submit them to the HOA and start digging. I was originally planning on doing a 12" foundation due to the tendency of the earth to shift in my area and supporting of the natural stone finish. does this seem too thick? If not, how do I frame the foundation so it finishes nicely if some is above grade?

I'll start a thread for my build as soon as the HOA approves the plans :-)

[mstang1988]

I should specify it's a 42" oven.

[gdest]

12" sounds way to thick. What you need to do is concentrate on your footing. Dig your footing down to what ever depth your local building codes suggest and lay down a layer of rock and compact this. This is where you can be 12" thick.
Then you can lay in your rebar and tie that together. For the interior of the slab you can usally get away with laying down wire mesh but you can also install rebar. This slab should not be more then 4" thick. Any thicker you are wasting money since this section of the slab see's no real force or weight.

[mstang1988]

Originally Posted by gdest

12" sounds way to thick. What you need to do is concentrate on your footing. Dig your footing down to what ever depth your local building codes suggest and lay down a layer of rock and compact this. This is where you can be 12" thick.
Then you can lay in your rebar and tie that together. For the interior of the slab you can usally get away with laying down wire mesh but you can also install rebar. This slab should not be more then 4" thick. Any thicker you are wasting money since this section of the slab see's no real force or weight.

The load I am worried about is the stone here. 5" thick and about 1 ton/ 75sqft and if I remember right it's about 500 square feet of stone. Combine the weight of stone and the cement block footer, hearth, insulation, cement counters and cement roof it's going to be on the heavy side of things.

http://www.fornobravo.com/forum/f35/...atio-8861.html (My Kitchen Design, What material for patio and counters?)

[Tscarborough]

Add up the estimated weight of everything and divide by the foot print and you will find that the actual structural requirement falls somewhere around packed dirt. In RR, I assume you are east of 35 in the gumbo, so you will want to go a little better than packed dirt, but the standard for you is:

8-12" of compacted road base extending at least 6" beyond the edges of the final slab.

4" concrete with #3 rebar 12" O.C. in both directions. If you are truly paranoid, you can put a beam around the perimeter that is 8x8.

I am here in town, so call me if you have any questions:

Tom 821-3303

[mstang1988]

Originally Posted by Tscarborough

Add up the estimated weight of everything and divide by the foot print and you will find that the actual structural requirement falls somewhere around packed dirt. In RR, I assume you are east of 35 in the gumbo, so you will want to go a little better than packed dirt, but the standard for you is:

8-12" of compacted road base extending at least 6" beyond the edges of the final slab.

4" concrete with #3 rebar 12" O.C. in both directions. If you are truly paranoid, you can put a beam around the perimeter that is 8x8.

I am here in town, so call me if you have any questions:

Tom XXX-XXXX

Tom,

Yes I live east of 35 around the outlet mall. You seem to be a pretty experienced builder, how tough do you consider this project? Do you have any good sources on materials in the area besides firebrick such as mortar etc?

[Tscarborough]

I have sources for everything you need, I am in the trade.

[mstang1988]

Originally Posted by Tscarborough

I have sources for everything you need, I am in the trade.

Fantastic! Also, I want to do all the work but the exterior stone. Do you have any good suggestions on who will do a good job at the right price? I would actually like to learn to do the stone but don't want to ruin my wonderful to be oven.

I was also told to leave 5" for the stone guys. Does this seem correct?

I also noticed the original plans suggested 6" foundation but you suggested 4". I'm surprised, I would have expected 6-8" in our area. I'll check the load and find out I suppose.

[Tscarborough]

You can do 6", it won't hurt anything, and will help if the sub-base isn't perfect. You should do all of it yourself, but if not, I can give you the names of a couple of masons.

[mstang1988]

Originally Posted by Tscarborough

You can do 6", it won't hurt anything, and will help if the sub-base isn't perfect. You should do all of it yourself, but if not, I can give you the names of a couple of masons.

How hard is it to do stone work like that? I know the materials are pretty cheap when I looked into it. About $100 for a ton if I remember right.