oven stand size

[thebigt]

Re: oven stand size

Thanks for the compliment,
I just noticed that we left you hanging with a couple of conserns.

Funny you mention the prep table....The area next to my oven is a pain to mow the lawn and I am looking at eliminating it. A nice prep area is what I was thinking of filling it with.

[david s]

Re: oven stand size

A cantilevered supporting slab works well for an oven because most of the weight is inboard from the perimeter.The problem is that it is more difficult to arrange the form work for unless you cast the slab and lift it into position on you columns.

[thebigt]

Re: oven stand size

Casting the slab on the ground is an option but I'd have to do it in 4 chunks so that I could fit them inside my tractor bucket to be lifted up. My current slabs are arlctually in 2 pieces and are 26x25 each and that was the only way I could lift them was with the tractor

[NCMan]

Re: oven stand size

You want to pour it in place, in one piece.

[Gulf]

Re: oven stand size

...........If I did catch on would a 2 1/2 slab work(That's what my current hearth slab is making the 52"x50" actually a full 5" and only the portion that cantilevers would be 2 1/2) be enough or do I need the full 3 1/2 that a 2x4 would provide me?

Ouch! T,
I read this the other night, after some very long hours at work, and I did not catch that. If I read that correctly, two and one half inches is not any where near thick enough for cantilevers. Though, the compression strength is probably ok, there is no way to "build in" the tensile strength. That takes thickness and reinforcement. I am sure glad that we caught that in time .

Had your existing hearth slab been a full 3 and 1/2" thick, I think that another 3 and 1/2" would have been fine for the rest of the overhang. Since that is not the case, I think I would go with at least a 4" thick slab with 1/2" rebar on 1 foot centers.

I guess that I assume too much, so I am going to ask a couple or so questions before we get too much further along.

Do you have reinforcement in your 6" thick base slab?
Did you put reinforcement wire in your 2 and 1/2" thick hearth slab?
Do you know if the columns are solid concrete?

Below are some drawings that I played with based on your stands dimensions. They were done in powerpoint and are not to scale. They are based on standard lumber dimensions in the US. Done in this way you will be adding just a little over 5" to each side and 9" to the front and back. That will bring your existing 50" X 52" to just a little over 60" X 70". Going back to some earlier figures on this thread, those dimensions were plenty for a 32" oven. With some smaller metal plates and studs, or careful stud placement, I am sure that you can easily fit a 36" oven on this form.



I originally advised all 2X's for your forms, but I think that buying one 10' 2X8 will make forming it easier for you. Using 2X6's for the sides of the form in this way will allow you to adjust slightly for level. If you go with the plywood alternative, you may need to go with 2X8 stock in place of the 2X6's. That would give you more surface for the deck screw to bight into.
Edit: Sorry about the 2D powerpoint sketches, but I don't draw by hand in 3D either

[thebigt]

Re: oven stand size

Thanks for the drawings and advice

To answer your questions above the 6" bottom slab has 1/2" rebar on 1 foot centers. The top slabs are each 50x26 and also have rebar on foot centers. Both were poured using 30MPa concrete that I had delivered. Regarding the columns they are solid concrete.

[thebigt]

Re: oven stand size

How many 2x4 posts going to the ground should I have? Every 16 inches?

How long does the concrete need to cure before I build on it? Guessing it'll be late May or Early June before the risk of frost goes away and I can get it poured. Damn Canadian weather lol

[Gulf]

Re: oven stand size

How many 2x4 posts going to the ground should I have? Every 16 inches?

How long does the concrete need to cure before I build on it? Guessing it'll be late May or Early June before the risk of frost goes away and I can get it poured. Damn Canadian weather lol

3 to each side should do it. That is pretty close to 16". 17.5" for the sides and 15" for the front and back. You might want to put a diagonal kicker in the middle of each side to guard against bulging. But, that is not usually a problem on a 4" pour on that short of span.

I don't know what ya'll call a frost, but you can "tent" a tarp over the pour and put a heat lamp under it. Just make sure that it is above the slab and doesn't touch the tarp. We can get buy down here most winter nights with just a light bulb under the tarp. That may help you get a head start .

You want to keep it covered for at least two weeks to keep it from drying out for the cure. (it will keep gaining in strength for about 50 years, it is all down hill after that ) The slab will be strong enough after two weeks, but it want be dry. If you place a water proof membrane (plastic) between it and your insulation layer, that wont be a problem. You can start right away. It will eventually dry from underneath. If you use sealers, waterproof paint, etc. you will need to follow the products instructions.

Edit: I drew those support posts in the drawing, resting on a block to help spread the weight over many more square inches. The blocks will need to be resting on firm soil, though. Just in case the ground thaws out during the pour .

[stonecutter]

Re: oven stand size

I don't know what ya'll call a frost,"....

I'm not sure about where bigt is from, but my father was born in Montreal and came to the states at 15. Up there you measure the frost with a tape measure.....

[Lburou]

Re: oven stand size

Awesome advice Gulf!

I made a base for a barrel oven as well. You can adapt your base and make the pompeii oven the way Gulf suggests. Don't forget the steel.

[thebigt]

Re: oven stand size

Yeah it's still hitting -20C (-4F) overnight some days...in fact we got more snow yesterday! Though by May a tarp and a heater should work fine.

[thebigt]

Re: oven stand size

Looks like sourcing refractory mortar will be a challenge, but I did manage to track down the ingredients for homebrew mortar. My challenge is that the fire clay and silica sand are 2 hours away(50lb bags of sand need to be pre-ordered), not a big deal as I pass through to go to the lake that way, but don't want to be short. Approximately how much fireclay and silica sand will I need for a 36" oven? Both ingredients come in 50lb bags. Fireclay is 16.95/bag and sand is 19.99/bag

[Gulf]

Re: oven stand size

Looks like sourcing refractory mortar will be a challenge, but I did manage to track down the ingredients for homebrew mortar. My challenge is that the fire clay and silica sand are 2 hours away(50lb bags of sand need to be pre-ordered), not a big deal as I pass through to go to the lake that way, but don't want to be short. Approximately how much fireclay and silica sand will I need for a 36" oven? Both ingredients come in 50lb bags. Fireclay is 16.95/bag and sand is 19.99/bag

TheBigT,
I was hoping that someone with some experiece with fireclay would chime in. Maybe this bump will help. I was never able to source fireclay in my area so I don't have any first hand knowledge about it. I started out with a refractory mortar, but then quickly switched to using the screened (sieved) settlings from my wet saw as a substitute for fireclay. That was for monitary reasons .

You didn't mention the the other two components of homebrew, portland cement and hydrated lime. I assume that you will be able to get these locally. I actually used Type N mortar for my homebrew. Type N mortar is 1 part portland and 1 part hydrated lime ("or the equivalent") in the states". I just adjusted the formula to match.

20 bucks for a 50 lb. bag of sand............... What do they charge up there for "masonry sand"?

I guess your main question (Approximately how much fireclay and silica sand will I need for a 36" oven?) is a little difficult to answer. That would depend on just how exact you plan on cutting your bricks to fit. Many have cut there bricks on jigs, and used formulas for precise cuts. Their builds would not require nearly as much mortar as mine. I only attempted to make my inside cuts tight fitting. And again, there are others who only cut their bricks with a brick set in to halves, thirds etc. They probably used more mortar than me on an equal number of bricks.

If you can get the portland cement, hydrated lime (or type n mortar), and can source some "masonry sand" locally, I would just "over buy" the fireclay. Since it is is only 1/6th of the formula, I would try 3-4 bags. Also, since it doesn't have to be "preordered", you could take it back the next time you go to the lake .

[stonecutter]

Re: oven stand size

My latest oven is 33", and I used just under one 50# bag....I still have some left. It was used in the reinforced cladding I covered the dome with too. 2 bags should do it for a 36".

[Gulf]

Re: oven stand size

My latest oven is 33", and I used just under one 50# bag....I still have some left. It was used in the reinforced cladding I covered the dome with too. 2 bags should do it for a 36".

Stonecutter is a pro. His ovens could probably be just drystacked with no mortar. You might better split the difference and pick up 3 bags