Actual foundation size for a 42" oven

[astroflash]

Hi,
I'm a newbie living in Prescott, AZ, and have started excavating the foundation for a 42" pizza oven. My question to all of you that have built ovens before me is what was the actual foundation measurements for your oven as the ebook actual has 2 different size foundations for a 42' oven. Any feedback would be appreciated.
Barry

[lane]

Re: Actual foundation size for a 42" oven

I am about half done with my dome. I used the 77" by 86" size for my foundation. Hope that helps.
Lane

[astroflash]

Re: Actual foundation size for a 42" oven

Hi Lane,
Thanks for the information.
Regards,
Barry

[jmhepworth]

Re: Actual foundation size for a 42" oven

My foundation slab is 88x79. Here's what went into figuring that number: My stand is 5 blocks by 4 1/2 blocks. I wanted 4 inches of reveal on the sides and back with 6 inches of reveal in front (for us non-techies, reveal means the part of the slab that extends beyond the blocks that form the stand). The blocks are 8x16, except they are about 3/8inches less than that for mortar. I urge you to dry stack them close together, so they will be 3/8 inch shorter and narrower than 8x16, totaling about 78 by 71. Adding 10 inches to the length and 8 inches to the width gives 88x79.

I did a 10 inch curved cantilever, so I ended up with extra room at the back, so my foundation could have been shorter, but I'm not sure it could have been a half block shorter. The primary consideration after making sure it will be big enough for the oven and the insulation you plan (a blanket will take up less space than loose insulation) is to not have to cut blocks.

Joe

[jmhepworth]

Re: Actual foundation size for a 42" oven

You got frost heave in Prescott. Are you planning footings or a floating slab?

Joe

[astroflash]

Re: Actual foundation size for a 42" oven

Hi Joe,
You are correct in the frost heave in Prescott. Because of the oven location, I've had to excavate, by pick and shovel, quite a few cu yards of dirt. I was planning a slab over several inches of 3/4" rock and hope that qualifies as a floating slab. What do you think?
Barry

[dmun]

Re: Actual foundation size for a 42" oven

I was planning a slab over several inches of 3/4" rock and hope that qualifies as a floating slab. What do you think?

Six inches of crushed rock should suffice, if the area is well drained. If you are building in the lowest part of the yard that floods when it rains, then more may be required. The idea is that if there's no water, there's no frost heave.