Rebar Enclosure?

[paulkjrobbins]

Hello amazing forum contributors,
I am getting ready to frame my enclosure walls for my 36" pompei. I built my oven at an angle because of some changes that I made after my hearth slab was poured. As a result, there is one spot that steel won't fit and leave room for vermiculite fill. The choices that I see are to extend out the oven base to support the enclosure at that point, OR could I possibly just weld a 1/2" rebar frame to build my enclosure on and save myself 3 inches?
I have made such a frame for a fireplace grill and it is very strong. Here is what I am thinking:

- Weld a 1/2" rebar frame and roof
-Attach to hearth using brackets that are welded to frame
-Attach hardiboard to inside of frame walls
-Attach stucco lath to hardiboard and tie to rebar
-Finish with river rock

This would also enable me to be really flexible with the shape of my dome finish. I am thinking of perhaps doing a cylinder to mimic a castle tower and then doing a metal (copper or steel) roof to mimic a pointed turret roof.
This is also tempting because I was planning on making my own chimney cap for my duratech chimney and I could make one that looks like a matching turret roof.
Any thoughts or advice on a rebar cage frame? Thank you in advance for any advice.

[paulkjrobbins]

Thinking this through more. I would probably use 1/4" durock, since it has a lot more give that hardiboard, and put it on the outside of the rebar.

[mongota]

Could you build your rebar skeleton for the turret, say with 8-10" gaps between the rebar...then cover the outside of it with expanded diamond lathe. Secure the lathe to the rebar skeleton with rebar wire ties. Then do a render over the lathe. Then stone against the render?

I did expanded diamond lathe over my blanket insulation, then stucco, then stone.

[paulkjrobbins]

Hi Mongo,
That sounds a lot easier. I was only thinking of cement board in terms of contributing to waterproofing, but as long as I have an overhang on the pointed roof and waterproof the bottom few inches I don't see there being much need for backerboard on the walls. I have a couple of rolls of lead flashing I could use to waterproof the bottom of the walls.

[david s]

I built a ferrocement structure to house my kiln in ferro cement using 8 and 6 mm bar and chicken wire. It is only around 25-30 mm thick and extremely strong.
It may help you, start here
https://community.fornobravo.com/for...879#post262879

[mongota]

Hi Mongo,
I was only thinking of cement board in terms of contributing to waterproofing,

Just for clarification, cement board is not waterproof. While the board itself will not be damaged by water, it can absorb water and if saturated, allow it to pass through. In shower construction that's why it's common to see cement board coated with a surface applied membrane; Kerdi, RedGard, Hydrodan, Ardex, etc. Or at a minimum to have a drainage plane behind it; tar paper or 6-mil poly.

After I did my render, I treated it with a couple coats Thoroseal. It's a cement-based coating that provides protection from liquid water, but allow moisture vapor to pass through. That was my protection until I got the stone veneer installed. A 50-lb bag was around $35-$40, enough to do three, maybe four coats. I coated the dome and carried the Thoroseal out a few inches on to the slab. The stone veneer covers that return on the slab.

[paulkjrobbins]

You guys have given me some really golden direction. Thank you! I think I am going to implement all that has been said here. I have been looking into ferrocement and it looks like the way to go in a tight space. I am thinking of sandwiching a galvanized cattle panel between two layers of diamond stucco lath, although I realize I am going to have to do some serious pushing to get the grout through the lath to the middle so I might leave off the outside layer so I can push in from both sides and then add it on afterward and risk there being a cold joint there. It might be ok, I'll do a test run on some scrap to see how difficult it is to push mortar all the way through the lath. The alternative would be to use hardware cloth but diamond lath is a lot less expensive. The cattle panel should give me plenty of strength so I won't need rebar to stabilize it. I have seen others on the internet say that the cattle panel approach doesn't buckle until after 5-6'. My tallest will be around the 3' mark.

I will attach steel studs to the roof in an octagon pattern and screw hardiboard to them and then finish with aluminum flashing bent and flashed to make a traditional pointed turret roof. I'll probably paint the roof pieces with direct-to-metal paint the desired color.

On the outside of the walls, I'll do some coats of thoroseal 581 followed by the stone veneer (1-2" rainbow river cobble to go with the miniature tower look).

I plan on using Type N mortar for the ferrocement and rock veneer.

I could even put a bamboo cutting board "drawbridge with chains to the oven that would have to be protected/removed when not in use of course. Having fun with this idea.