Where to begin, Foundation questions

[mitchc]

Hi, new here but hopefully I'll get some good answers for the construction of my oven before I start it. I'm finishing a pool remodel project that has run on for quite a while. I'm Trying to build a fire pit now then possibly on to the oven build. I've searched a bit of the archives but found nothing addressing my concerns which will undoubtedly affect how, and when I can begin.

I had a new pool/ patio deck poured last fall, and although I figured I would eventually look into an oven, I was not considering the strength in the general BBQ island/ oven area at the time. I made sure to run all the other infastructure I would need, like sewer/water/elect. and even gas supply line. Unfortunately, due to my lack of consideration before pouring the deck, I am now faced with having nothing more than the standrd deck thickness of 3-1/2" - 5" thick to serve as my foundation.

Being value concious(cheap) and currently unemployed, I therefore need to plan on an economical approach to this. I am pretty sure something can be done to limit the overall size and weight (and cost) of the oven to make do with the deck foundation I now have to live with. So I suppose it will need to be: small in size; limited to igloo style; mounted on top of a minimal stand structure to reach this goal. Does it sound like this plan is doable and is it possible to build a nice oven given these circumstances, and for shooting myself in the foot with regard to the lack of a hearty foundation?

I welcome any input from anyone else who faced this "deck as a foundation" issue or had room restrictions forcing them to downsize their project to solve their problem.

BTW: I live near Sacramento Ca @ about 200' elevation, so Frost is not much of an issue if that affects any potential options...

First of many questions I'm sure.

Mitch

[Ah Makdapitsa]

Re: Where to begin, Foundation questions

Hi Mitch:

I plan on using my existing deck as the foundation for my oven. However, my deck is a little more beefier than yours and it is properly prepared with 8" of crushed aggregate that's been compacted before concrete placement. Ground is deemed glacial till which has excellent bearing capacity. Does your patio have any re-bar in it ?

You've got several options.
1. Go for broke and live with what you got. If it works you saved some time and dough. If it doesn't, a fix involves dismantling the oven, and then jacking up the patio to make the repair. Not cheap and ugly.
2. Saw cut the patio the exact size of the oven foundation. Jack out the concrete, dig it deeper, add aggregate, place expansion joint material around the opening and place a thicker a thicker patio slab. If you get any settlement it won't affect the balance of your patio because your oven will essentially sit on a floating slab, and the load of the oven will not stress the patio.

Being a cheap SOB I've already opted for Plan # 1.

[ATK406]

Re: Where to begin, Foundation questions

Hello Mitch,
Dapitsa maker poses some good questions regarding rebar/concrete reinforcement and the preparations below grade (soil compaction etc.). However assuming the worst (i.e. no concrete reinforcement and unpacked sand below) you should still be able to build a sound foundation for your oven.

I don't believe there is any rule that your slab must be below ground and flush with the surrounding area. If you wanted to avoid a stress crack/fracture of your previously poured slab, couldn't you cut a section of your slab the size of your intended foundation and pour another reinforced slab on top of this? This would provide a combined slab thickness of 8"-10". You may get a little settling over time (again assuming the worst) but it shouldn't affect the integrity of your base/oven.

I am a novice at this sort of thing and you may well be fine with the slab you have already poured. However there are certainly experts on this forum, hopefully they will weigh-in to help you make your decision.

Good Luck,
Regards,
AT