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Re: Slab & Frost heaves?
From the WFO board
Posted by Rado (18.104.22.168)
In Reply to: Re: Slab & Frost heaves? posted by Jim G.
The winter white snow falls everywhere, nature looks so beautiful, and absobloodylutely the freeze gets in the ground also under my oven.
Footings under-around the ground slab play important role in load bearing. No matter if it's winter or summer, footings support the weight of the whole structure, the slab is strengthen by and it rests on footings too. The oven sits on walls which sit on the whole surface slab and all that sits on footings.
Below is on floating or non floating ground foundations, and further below also on my new design:
For FLOATING slab, the slab needs its footings, same as per my oven building CDs. This is not hard to do; first dig the whole surface area needed for the spirit-leveled slab (calculate with the slab thickness and ground around the oven if you were about pave it etc.), then on edges dig deeper for footing, 4 sides. Mix concrete and pour it into footings around placing one reinforcing bar into every one of all 4 sides 4 bars only for the footing job in total is minimum. Then continue pouring concrete into formwork for the slab which is reinforced with metal mesh, footing and slab are poured together at one time. I almost never buy delivered concrete, I mix and pour whole job by myself no other help. Footings might appear primitive but are very important. One reason for footing is they prevent and won't allow water getting high under the slab (this reason is a big one just ask builders why.) Other big reason was mentioned at start, ovens or most buildings are heavy (this is not work on walk pathways or car driveways that will crack often) if the footings are inadequate the slab cracks because the ground is moving plus rain/ground water will wash soft stuff from under the slab, and if footing wasn't present it is enough when ground drops e.g. a little 1mm in a corner will make the slab to crack. And 1mm at ground level makes the crack angle pressure bigger higher it reaches. With footings it'll rather rock but will not crack. Make a nice bed of stone gravel under of up to 4" - 10cm in freezing world locations and pour concrete on top.
For firmly (NON FLOATING) sitting buildings, footings must be dug until hard soil (sometimes called rock) is reached and also extending 30cm 12" below frost level. Then pour cheaper concrete in, less cement concrete blend of stones with sand and Portland cement in ratio of 5:1 - can contain stones of 10cm 4 plus, and this layer does not have to be reinforced with metal bars. Then you put the slab with its reinforced footings on that. You can build house this way. Surface area can be backfilled to desired slab thickness to save concrete money & energy used for mixing. It is not difficult or revolutionary, it is common sense.
My NEW DESIGN:
For world's wood fired cooking enthusiastic community, I have come out with my Masterly Tail oven design as I call it and do for work. As several people may know already Masterly Tail oven design cd is not lucking details and has 1000 big photographs (one thousand.) As per heat differences I have developed also cold climate frost/freeze or heavy use for business non-crack deco entry to the ovens - double half building brick work; it is high quality and very easy to do, I used it a lot in Europe. Recently I have built other Masterly Tail oven that includes this system (plus the oven is built low set sitting on ground and is fully covered by soil and decorative thick grass types grow on top) it was added into the cdrom now ... people who need it additionally and have Masterly Tail cd already let us know we can email it to you in smaller picture format together with the entry diagrams, the e-mail will have ~500Kb to 1Mb file size as there will be of up to 20 photos, mention your name with this request as well (otherwise all photographs in the cd are of large size.) Link to the page is below although it isn't done just yet, too hectic on my end for the last 2 months. In 1 go I wish to spend all 4 year seasons in Alaska. r
Re: Slab & Frost heaves?
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