oven stand size

[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.

[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

[NCMan]

Re: oven stand size

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

[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

[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

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.

[thebigt]

Re: oven stand size

Ouch! That is high. I had two choices for firebrick on my oven. One was a pressed firebrick that was very close to perfect. I used those for the floor. Another, cheaper option, was a wire cut firebrick that I used for the dome. The wire cut were not as perfect in symmetry as the pressed. But, I figured since they would be mostly cuts, what the "hey" .

I did ask the one place about "seconds" and the masonry place said they didn't carry them....I will ask them about wire cut though. Seems my options are super limited here.

[thebigt]

Re: oven stand size

If it were me, I would not sandwich the plywood. I know it sounds more dificult, but I would form around the existing slab. It will take more 2X material but less plywood. If it is formed with enough support, 1/2" plwood is ok. It can be formed totally with 2X material. I have done that on several projects where I was going to reuse 2X lumber on another form or a later project. Most times I would form it to where I made as few cuts as possible.

[ATTACH]41800[/ATTACH]

I couldn't find an example on the web, but maybe you can figure out what I was trying to draw in powerpoint as an example. Though not to scale, I am trying to show a form around something like your stand using 8' 2X4's with no cuts. The support kickers will have to be cut though. Using deck screws speeds up the assembly and disassembly of the form boards for later reuse.

I think that this is starting to make sense to me now...Lets see if I am really am catching on

What you have depicted is several 2x4's screwed together to box around the existing slab. To make the slab wider I would just add more 2x4's. So if I needed to add 6" to each side of the slab I'd need 4 - 2x4's per side. Then I would place a piece of plywood on top of that. This along with the legs going down to the ground would provide the support that I require, is that correct? Then I'd put another 2x4 box on top of that which would act as my concrete form....Did I finally catch on or am I still lost lol?

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 cantelievers would be 2 1/2) be enough or do I need the full 3 1/2 that a 2x4 would provide me?

[stonecutter]

Re: oven stand size

Yes it is .............. and I understand what you said just fine..............But, do you think that every newbie......with no forming experience ......... will?

just sayin'

By all means, draw away...if you feel like it.

[NCMan]

Re: oven stand size

Looks like you may be doing those schematics after all.

[Gulf]

Re: oven stand size

Simplicity is the ultimate sophistication.
Leonardo da Vinci

Yes it is .............. and I understand what you said just fine..............But, do you think that every newbie......with no forming experience ......... will?

just sayin'

[stonecutter]

Re: oven stand size

Thanks Stonecutter ,
You just saved me a lot of time from drawing a "schematic"

Simplicity is the ultimate sophistication.
Leonardo da Vinci

[Gulf]

Re: oven stand size

Just build an L shaped form around your existing slab, make some T shaped supports , and away you go.

Thanks Stonecutter ,
You just saved me a lot of time from drawing a "schematic"

[stonecutter]

Re: oven stand size

Just build an L shaped form around your existing slab, make some T shaped supports , and away you go.

[Gulf]

Re: oven stand size

No plywood sandwiched between it is. When you suggest that I box around my existing slab I'm assuming that it is support for the plywood is that correct?

Yes: for me Stonecutter, and I think a 3+ from NCMan. For what ever you deck the form with, just set the form lower by the thickness of your decking ("plywood").

For the boards that touch my existing slab would those be anchored into the existing slab to hold them up or would you brace with boards going down to the ground?

You will have to support the outside of the cantilevered form from the ground anyway. Unless you already have good masonry bits, and a good hammer drill, drilling into anything but fresh concrete can be a btch So, you might as well use one 2X4 post (for each support) for both at the same time.


As you can tell concrete is not my specialty

You also mentioned in an earlier post that you had "no brick laying experience"......... When your build is finished.............you want be able to say either........anymore

Give me a couple of days and I will draw you a rough set of plans for your form.