Foundation Thickness

[thebadger]

Gang,

Planning the build for next year but trying to get all the details worked out...

"The Pompeii plans call for a minimum 5 1/2 -6 inch slab if I recall correctly"

We had a 15x15 patio poured (I guess the standard 3 1/2 thickness) in one corner I had the contractor make it thicker for the pizza oven (I wasn't home at the time to supervise but trust he did what he told me - at least a 6 inch deep 6x6 area. Since the grounds slops he indicated it is probably thicker - maybe up to 8 inches and my wife told me it looked like he inserted rebar.

Any concerns/issues/anything I can do before I lay my cinder blocks?

I don't think I'm going to cover the whole thing in a heavy stone, probably stucco and tile (possibly a stone veneer around the cinder block base).

Thanks
Dick
Ohio

[asudavew]

Re: Foundation Thickness

I think it will be just fine.

[Unofornaio]

Re: Foundation Thickness

(I wasn't home at the time to supervise but trust he did what he told me

Why the $#@ cant I ever get customers like that??

As to the question, corners of patio slabs are usually the weakest simply by physics. If this area was thickened by the contractor you should be able to dig out the dirt on the side and see PROOF. Otherwise call your bookie because you might as well place a bet on if it will be ok or not. 4" on a corner is very risky..

If it is not thickened you can always pour a nice footing in that corner doweled into the slab and build on this.

[Les]

Re: Foundation Thickness

To add to this - I noticed you are in Ohio. Are you going to be affected by soil heave? I don't think you will have a problem in regard to the weight you are putting on it.

Les...

[asudavew]

Re: Foundation Thickness

Why the $#@ cant I ever get customers like that??

I know what you mean Les.

I used to do kitchen remodels. Counter tops, cabinets, etc. etc.

I once did a job where the customer was an older man, in his 70's I'd guess.

Well when we got there he was sitting in the living room watching TV resting in a rocking chair.

As soon as we started to work, he moved that rocking chair into the kitchen, and watched the whole time!

Talk about nerve racking.......

[RTflorida]

Re: Foundation Thickness

I lived in northeast Ohio for my first 35 yrs, the frostline was considered the 3' (36 inches). Any footings, slabs, fence post, etc needed to be set to this depth to avoid soil heave. Not sure about the southwest (Cincinnati) area.

[thebadger]

Re: Foundation Thickness

Not sure aboit soil heave - sorry.

I'm pretty sure it is at least 6 inches in that corner and possibly eight. I will dig a little to make sure.

This 15x15 slab was built on top of where are old deck was. I think there are 4 concrete posts buried in the ground where the old deck beams rested on. I'm pretty sure he left those in. Not sure where they are in relation to the oven location.

Someone mentioned adding a slab on top. Would this work/offer the protection I need?

Other options?

Thanks
Dick

[Les]

Re: Foundation Thickness

Dick,

Heave can be a nasty thing - you can contact the city and they will tell you what depth your foundation should be. But your soil is the key. I live in an environment where it can get pretty cold. My lot is sitting on DG, not a problem. I have friends a few miles away and they are on clay - big problem. Adding a layer on top will not solve the issue - you need to go down. As I mentioned before, 4 inches will support a butt load of weight - it's movement you need to be concerned about.

Les...

[RTflorida]

Re: Foundation Thickness

Les, your right. I should have carried my thought a bit further.
To put it simply - movement of merely 1/4" - 1/2" could do serious damage to a Pompeii or cast refractory oven. I think most everyone has seen where a stone or brick fireplace have settled (or the surrounding structure) and the cracked mortar and bricks associated with the settling.
In the case of an oven we are talking about a self supporting dome; it's structural integrity would certainly be compromised by settling, upward, or lateral movement.

RT

[Les]

Re: Foundation Thickness

RT,

I forgot to add something in my post - great choice in moving to Florida!

I went deer hunting in Ohio a few years back... Friggen COLD!!

Les...

[thebadger]

Re: Foundation Thickness

Les/RT;

Thanks. I looked up and the building inspection web site says the frost line is 30 inches...

I thought I was doing the right thing asking my patio guy to make the slab 6+ inches..

What are my options? I can't tear the whole patio asI just put a post for the pergola in that corner.

Any advice would be appreciate.

THanks
Dick

[Les]

Re: Foundation Thickness

Dick,

Again, it's about your soil. If your house is sitting on an old lake or river bed, you may have a problem. If it's located on an old decayed mountain top - you're probably good. In the worse case scenario, I would think you could set a few holes at the correct depth and then tie them into your slab with rebar. I am not a PE or contractor, I'm sure that someone here can give you solid advice. As a thought (and a few glasses of wine), you may get away with setting your block on expansion joint material. That's totally outside the box and I am unaware of anybody doing it. EVERYBODY - input please...

Les...

[RTflorida]

Re: Foundation Thickness

Lets hope Uno chimes in again, he is the resident conrete expert. I'm certain he will have a solution. The man "is concrete".

[Archena]

Re: Foundation Thickness

Les, your right. I should have carried my thought a bit further.
To put it simply - movement of merely 1/4" - 1/2" could do serious damage to a Pompeii or cast refractory oven. I think most everyone has seen where a stone or brick fireplace have settled (or the surrounding structure) and the cracked mortar and bricks associated with the settling.
In the case of an oven we are talking about a self supporting dome; it's structural integrity would certainly be compromised by settling, upward, or lateral movement.

RT

Hmm, wouldn't the hearth slab protect the oven to a degree? It'd be the stand I'd worry about initially - that gives way and cracks will be the least of your worries.


Oh, and I trust my plumber if that makes you guys feel any better. I gotta admit to a little nervousness - I'm having several issues fixed at once in an old house - can we say expensive? Now if he can just get here to fix my pipe - I miss having water.

[Unofornaio]

Re: Foundation Thickness

Les/RT;

Thanks. I looked up and the building inspection web site says the frost line is 30 inches...

I thought I was doing the right thing asking my patio guy to make the slab 6+ inches..

What are my options? I can't tear the whole patio as I just put a post for the pergola in that corner.

Any advice would be appreciate.

THanks
Dick

The picture I have of this patio is the oven will be located on an outside corner and that sounds right from this post. Having the pergola post in the corner is not a problem for the retro fit (other than appearance) if you do as I mentioned "you can always pour a nice footing in that corner doweled into the slab and build on this." you will be fine.

There are 2 ways you can do this:
1. Dig out under the edge of the slab (one side at a time) and pour a footing under the slab. if you go back 10" and down 3' or so the slab corner is going to rest on this footing. then repeat on the other side.
2. Dig out under going back only 4" and have the remaining 6" outside dowel into the slab corner with rebar to connect the 2. digging this out with post whole digger first then carving out the under side is a good way to go. If you keep the dirt edges nice and straight and trimmed you do not need to use a form.... awww forget it I will post a drawing...

By building on this I mean the new footing (under the ground would support the slab