some questions for the experienced

[ericecon]

My oven is underway: 40 inch diameter, roughly 8 courses up. There's 2" ceramic fiberboard underneath and the floor is 2" firebrick tiles. The dome is made of standard size firebricks cut up and there will be 3" of ceramic fiber blanket on top.

First question: There are some gaps between bricks on the interior. Should I be concerned? Should I fill them with mortar?

Second question: The oven is expected to be 24-25" interior height at this point. Should I take some courses down and try for lower? I will make the entry the suggested 63% of the dome height. Will I be able to heat the oven properly or is there simply too much space in there?

Third question: Does the entry get insulated on top as well? I plan on covering the oven with stucco, including the entry.

Thanks in advance,
Eric

[kanoer54]

Re: some questions for the experienced

Eric,
Welcome to the forum. I live just south of St Jacob, not far from you in Aviston. I think others may be able to answer your question on the mortar gaps on the inside face of the oven bricks.

It is my understanding the typical height of an oven is about half the height, more or less. Hence 40" diameter/20" high. The taller the dome the more wood it will take to heat it up. I went the other extreme on my oven. I have a 38 inch diameter oven but it is only 16-1/2 inches high. I have no regrets. It heats up nicely and holds heat for several days. Others may have more in-site on this but I would consider lowering the height a couple inches.

3 inches of insulation is good, but in the case of insulation, there is no such thing as too much. I have a round oven and round containment around the oven with 4 inches of ceramic fiber insulation and then filled with 3 bales of course vermiculite.

Third question... I would not waste money on insulation for the oven entry. That is not where you are trying to store the heat.

Good luck with your build and post pics...they are worth a thousand words.

jon

[ericecon]

Re: some questions for the experienced

Thanks for the reply.

I've started taking down the top 4-6 courses. I've been using a cold chisel, hammer, and rubber mallet. Is there an easy way to get the mortar off the bricks that appear reusable? are they reusable, if I don't see any cracks?

Now to figure out a form.

Jon (Kanoer), where did you get your supplies? I drove to Hi-temp in Fenton for mine, but if you have a closer source let me know.

Thanks,

Eric

[kanoer54]

Re: some questions for the experienced

Eric,
Others with more experience may be better to properly answer about re-using the bricks, but I don't know of any reason why not as long as most of all the mortar is off them.

I did get most of my materials from Hi-Temp in Fenton also. I did need a few extra fire bricks and found them at Richards Brick in Edwardsville, but that is about all they carry is fire brick and a good selection of clay tile flue. They don't have the other refractory supplies like Hi-Temp.

As far as a form goes, search the forum for IT. It stands for indispensible tool and is a great tool for keeping the brick courses level and in line to keep the spherical shape for the dome. I used an offset IT so my dome height was less than half of the diameter. Others have used plywood or thick styrofoam.

good luck and post some pics as you can. We all love to see progress and especially what you have "cooked last night".

you're welcome to stop by sometime if you would like to see my oven.
jon

[GianniFocaccia]

Re: some questions for the experienced

While your oven is now 4-6 courses lower, take a few minutes to point mortar into the gaps where possible. You might consider using a wood template instead of an IT. It will allow you to create a custom dome profile of any height you wish. When you replace those bricks, make your mortar slightly wetter so when you press them into place, the mortar just squishes out past the end of the brick. You can clean the excess off later with a trowel and wet towel.

A hand-grinder with masonry wheel makes quick work of removing mortar that you haven't knocked off with a hammer. You want to use a respirator for this job.

[Novaslo]

Re: some questions for the experienced

Hey Eric,
Nice to see you are tackling this fantastic project. For your question on Gaps, we would have to see some pictures. However, Some people plan for no gaps like I did, and others have mortar in each gap. It depends how you cut the brick etc. In the end, it all heats just fine. As long as the gaps are small, i don't think it will be an issue. If they are large and you can successfully get mortar in there, then that might work nicely.

Finally, the masterpiece that you will look at after your done is the inside of that dome. Be proud of your work and cook away..

Jon wrote a great response to your question. I would add, if it is so aggressive that your structure seems like it will be compromised, I wouldn't worry too much about it.
Make the best adjustments you can and get that dome down to around 20 inches high if you can.

That would be my advice.
Also there are pictures of the Indispensable Tool (IT) that I built in my build thread.
Check it out.
D

[ericecon]

Re: some questions for the experienced

Thanks for the replies and advise.

I'm definitely going with a form; just have to build it. Right now there's the soldier and 2 sailors left which starts the height at 9". I'm not sure if I'll take another course off but I'm shooting for somewhere between 18" and 20" for the interior.

Thanks again guys.

[kanoer54]

Re: some questions for the experienced

Eric,
I have a spare IT if you are interested. Other WFO items also. Free for your pick up.

let me know.
jon