Finishing the oven,starting at the brick

[Prairie Valley Bread]

I would like some help getting the steps in order to finish my oven.
There are a lot of gaps between my bricks and I need to fill in a couple of leaky holes.
Then, can I appy the insulation and chicken wire and then stucco over the
whole oven, and then put a seal coat on it?
What the heck is "render" and "brown coat" all about?
Any help would be appreciated.
Thanks

[Tscarborough]

Re: Finishing the oven,starting at the brick

Fill the gaps. "Render" is "stucco". Stucco is traditionally applied in three coats: Scratchcoat (it is called scratchcoat because it is left rough for better adhesion of the browncoat), browncoat (it is called browncoat because it is tinted to assure coverage over the scratchcoat, and also to assure coverage of the finish coat over the browncoat, and is used to smooth off the rough scratchcoat), and finish coat generally applied very thin, 1/4" or so.

So for a typical 1" thick stucco (1" applied at once is prone to shrinkage cracks, thus three coats), you have 1/2" scratch, 3/8" brown, and 1/4" finish (9/8" +/-)

[Prairie Valley Bread]

Re: Finishing the oven,starting at the brick

Thanks Tscar,
I'm covering the brick with blanket insulation, so why bother filling the cracks?
Can't I just put the chicken wire on the insulation and then stucco away?

[Tscarborough]

Re: Finishing the oven,starting at the brick

Because it makes for a solid mass of masonry. If you are using blankets, note that compressing them by the application of heavy wet stucco will both soak them and reduce their effectiveness as insulation.

[david s]

Re: Finishing the oven,starting at the brick

Because it makes for a solid mass of masonry. If you are using blankets, note that compressing them by the application of heavy wet stucco will both soak them and reduce their effectiveness as insulation.

Another good reason to cover the blanket with a layer of vermicrete before doing the render/stucco layer. It will set and leave you with a firmer surface to stucco on to. I've used rockwool blanket for a couple of ovens. It is a bit cheaper than ceramic fibre blanket and only marginally poorer insulator, but I wouldn't used it again as it is way too soft and compresses easily which makes the render/stucco or vermicrete extremely difficult to apply. It is also very water absorbent which also creates problems. Compared to ceramic fibre blanket which is far firmer, cuts better and hardly compresses at all (I use the 128 kg/m3). I won't be using rock wool blanket as dome insulation again if planning to add any mixed layers over it. Never had a problem with the ceramic fibre compressing though.These products may vary from different manufacturers, but this has been my experience.

[Prairie Valley Bread]

Re: Finishing the oven,thermal mass, insulation

Hi Guys,
I just chopped the bricks and mortared them in. The front face, inward, is pretty flush, but the back is up to an inch (2.50mm) wide.
So right now that's not filled in.
I've already put in about 40k's of mortar and it's expensive.
Can I just fill it with regular cement?
Or can I just insulate and cover with stucco?
When I bought the blanket, they said it would compress, but it wouldn't make a significant difference. Especially since this blanket is good to 1000 degrees, and I doubt I'll get over 500.
What do you think?
PS
Winter is coming. I have to get it sealed up pretty quick.

[Laurentius]

Re: Finishing the oven,starting at the brick

If as your name suggest, you will be baking bread, your oven will be above 500 degrees by a wide margin. If you are planning more than one baking session during a run, then you will need the additional thermal mass. You having gotten this far so a half-assed approach is not the way to proceed. Its better safe than sorry!

[Prairie Valley Bread]

Re: Finishing the oven,starting at the brick

Hi Laurentius,
So, do you think I should use the oven mortar to cover the whole oven ?
I am planning on cooking slow pork, for about 5 hours, would I need it for that?
I wouldn't want to be half assed about it, that's for sure.
Thanks for your help,
Cheers,
Tom

[Prairie Valley Bread]

Re: Finishing the oven, now the stucco

Hi Folks,
I did use some more oven mortar and smoothed it out.
Right, better safe than sorry.
Now I have another problem. I put on the first coat of stucco and apparently I didn't get he insulationa and wire mest tigh enought. Now I have a couple of soft spots that I am waiting to dry. Should I stucco over and hope it firms up, or should I slice into it and try and tighten it up somehow.
I appreciate any suggestions.
Cheers,
Tom

[Laurentius]

Re: Finishing the oven,starting at the brick

Hi Tom,

Normanly the stucco coat is a 3 step procedure, is yours?

[Prairie Valley Bread]

Re: Finishing the oven,starting at the brick

Yes, it's going to be a three coat process.
I am wondering if I can build it up over 1 inch to smooth out the dips.
Cheers,
Tom