New Design

[herrbeckley]

I tried to ask this question in my previous thread (beginner with a foundation problem) but got no response. Thought it might be seen on this new thread.

After a hiatus of eight weeks or so, I'm back at it. How does this sound to you folks. Two concrete filled brick walls spanned by cedar 4 x 4's to form a base. Then a layer of insulation, then normal brick, then hearth floor. Beams span only about 28" and the will be secured flush to one another. I think that the wood will be protected from the heat of the oven and cedar is a tough wood perfect for exposure to the weather. I'm about to get started on this (brick walls are complete), so if this is really stupid please let me know.

My original plan to use the arch for support was beyond my skill level (three collapses).

Very Respectfully,
Tom

[Les]

Re: New Design

Tom,

I think I need a sketch - it's hard for me to envision exactly what you are trying to achieve. In regard to cedar, it's an evergreen - soft wood. And ALL wood will rot in time. More so when exposed to heat and concrete. Just my opinion, maybe others will chime in.

Les...

[brokencookie]

Re: New Design

Two concrete filled brick walls spanned by cedar 4 x 4's to form a base.

I am confused as to why you want to use wood here at all. Concrete with rebar will end up being cheaper and much more duable. If you want the appearence of the cedar, put it on as a veneer afterwards.

Then a layer of insulation, then normal brick, then hearth floor.

This appears to be in the wrong order. It should be hearth floor, insultation, then whatever else. Remember, the insultation prevents heat from bleeding out. In your listed configuration, you would be heating the hearth floor and then heating the bricks ( are you making a retained heat oven ?). Ideally you should heat the hearth floor and keep that heat from reaching anything else by using the insulation.

Hope this helps
Bruce

[dmun]

Re: New Design

Anything structural in wood below the oven is a really bad idea. All you need is something junky to hold up your slab temporarily while it's being poured (I used scrap wood from skids.)

I don't quite understand about your fallen arch: some builders have built beautiful brick arches above their wood storage area but my theory is keep your hard work and finish materials for where you can see them. Really, just a plain old reinforced concrete slab is all you need. If you want a decorative arch, just incorporate it into whatever your outside finish material will be.

And yes, your insulation layer goes directly below the brick cooking floor. Four inches of vermiculite concrete, or two of refractory insulation board is suggested.

[herrbeckley]

Re: New Design

But it is done in German Bake ovens. I don't know if they use cedar, but a wooden deck made out of beams laid flush together, supported by two masonry piers, is a common method. The wood beams can support the weight as well as a slab. It's free (for me) if I use cedar, and cedar seems to be very weather resistant.

[karl]

Re: New Design

If you dimension the beams correctly (not only for strenght, but also for maximum bowe down) and insulate properly there should not be a problem. Cedar is an oily type of wood and, as you say, should stand the weather quite well (is used in boats). And it will be shielded from above anyway? Remember to put in a water resistent thin layer between the (whatever) layer that against the wood to avoid any moisture in that layer to wet the wood during prolonged periods. You should be very careful in doing the same between the wood and the concrete were the beams are anchored. It is very important for the wood to stay dry (dry up) for prolonged periods to prohibit rot. But, as is stated by others, you cannot assume that the wood will stay up as long as reinforced concrete (assuming you will use sufficiently robust reinforcement bars, - corrosion!).



regards from karl

[Antonio D.]

Re: New Design

Hi Tom,
I have run into the same problem. When we had our pool dug 3 years ago I had a base dug and filled it in with concrete. When I was ready to start my oven I realized my base was to small. I supported 5 inches of reinforced concrete with 3 1/2" x 3 1/2" x 3/8" angle iron. my base was 45" x 53". My hearth is 72" x 63". I made a 10" deep form and poured 5" concrete ( 10" around the outside and embedded 5" vermiculite concrete in the center.
check out my pictures.

Tony

http://www.fornobravo.com/forum/photoplog/images/4407/medium/1_IMG_0184.JPG[/IMG]

http://www.fornobravo.com/forum/photoplog/images/4407/medium/1_IMG_0196.JPG[/IMG]

[Antonio D.]

Re: New Design

Hi Tom,
I have run into the same problem. When we had our pool dug 3 years ago I had a base dug and filled it in with concrete. When I was ready to start my oven I realized my base was to small. I supported 5 inches of reinforced concrete with 3 1/2" x 3 1/2" x 3/8" angle iron. my base was 45" x 53". My hearth is 72" x 63". I made a 10" deep form and poured 5" concrete ( 10" around the outside and embedded 5" vermiculite concrete in the center.
check out my pictures.

Tony

http://www.fornobravo.com/forum/photoplog/index.php?n=1439[/URL]
http://www.fornobravo.com/forum/photoplog/index.php?n=1440[/URL]

[dmun]

Re: New Design

Hi, Tony,

I think you're trying too hard on embedding your images. You can either paste the [img]...[/img] data into your post, or hit the postcard icon above the text box and paste the URL of the image there.

[Antonio D.]

Re: New Design

Thanks
I'll try again

http://www.fornobravo.com/forum/phot...1_IMG_0344.JPG

[dvonk]

Re: New Design

Cedar is an oily type of wood and, as you say, should stand the weather quite well (is used in boats)

I would like to stress that wood permanently submerged in the water (especially sea water) will probably last much longer than the same wood in the outdoor condition, going wet and dry and in contact with concrete, make it humid for a long period of time. These conditions are completely different, almost nothing in common - oxygen, types of bacteria, fungus, and so on.

[berryst]

Re: New Design

herrbeckly
Cedar is not a tough wood. It is wimpy wood. It is weather resistant that is why it is used on roofs and siding. I live with cedar, have milled it and used it. If you beef it up...oversize the beams it could work. but don't treat it like strong wood. If you are going to put it in the ground it will rot.
The rot rate depends on the moisture content of the soil. Most applications here are to put the post in a steel saddle then concrete the saddle in place. If its exposed to weather it will last years if treated annually
berryst

[Jim Bob]

Re: New Design

I realize having a great supply of cedar is tempting, but if you really want a long lasting wood to use try cypress. I have 300' of it in my fence out back. It has been in place for 22 yrs and still looks good. If however, you could keep it away from the outdoor elements(rain, etc), then it should last much longer. My son used cypress in his outdoor kitchen as structural beams(2" x 14") They look beautiful and should last his lifetime. One difference of course is our locations. Being in WA is much different than Memphis, TN area. Rainfall, temps, & very hot summers(in Memphis)
Jim Bob

[herrbeckley]

Re: New Design

Thanks to every one for your posts. Very helpful. I realize this is risky, but I think this will work. Let me explain it better.

I have two 3-foot-high brick piers that are on a very well poured foundation. these piers are about 54" long and 15" wide, and they are parallel. I have four angle irons that span the piers at regular intervals.

So I have all of these new cedar 4x4's, 60 inches long. I propose to use these lying across the piers, one up against the next until there is a table top of these beams supported by the piers.

They will be held into place by the four angle irons (two of which are on the outside of the beams.

I will then cover the beams with mortar (will this rot the beams?), lay down one layer of common brick. Then a layer of vermiculite. then the oven floor. All of the weight of the dome will be distributed into the piers anr/or the angle irons. The beams will ony support their own weight and the floor/subfloor combination.

I will then complete the construction of the dome/outerwalls/roof.

Does anyone thing this is completely absurd?

TB

[Wiley]

Re: New Design

TB,
I'm all for alternative ideas and recycle, and seeing the variety of WFOs here and elsewhere on the web, I suspect the answer is "yes".

That being said, just why are you going this route? I, like Berryst live in the Pacific Northwest and here cedar (that's red cedar) has gone absolutely bonkers in price. I cannot imagine it has gone down in price elsewhere in the country. The idea you would bury the wood (OK hide or bury from view) and not use it for such things as rustic table legs (given the lengths you mention) or as a table top side to side as you plan with boxed in legs of the same 4 x4 as a prep table escapes me.

What would be wrong with getting "el cheapo" utility grade 2x4's and frame and pour concrete for a base? Or form up and pour your own concrete beams and side stack them like you're planning to do with the cedar, if access to where you want to build the oven is an issue. If cost is the issue how far are you from the batch plant? You can get "overage" really cheap if you have the time and not the money. Lots of alternative things come to mind, so I am curious as to why are you set on using the cedar this way?

Wiley