How bad did I screw up? Used the wrong mortar

[Novaslo]

Re: How bad did I screw up? Used the wrong mortar

So embarrassed to admit but my first 36" Pompeii didn't go as planned... All was well until building the dome. Trying to save $$$ I used type S masonry mortar for the dome. Also red bricks not firebricks. Is this thing gonna collapse on me? Should I tare it down and use the proper fireclay mix or refractory mortar? I plan on enclosing the dome in a square house to match the base. TIA

I guess one thing to bring up as well, where are you at in the build. You say that that your first 36 didn't go as planned...Is it complete, or did you just finish the dome?

There is a lot of work to be done after the dome is built to get it insulated and finished, none of which is easy. It is all work and every stage that I thought would be the easy stage, actually wasn't all that easy.

Looking back, building the dome went pretty fast and not all that hard. If you have not covered the dome yet, I would consider taking it down and changing out the brick.

I think the other important factor is oven performance.
My brother (At a hotel recently) experienced a guy that worked for the hotel, serving wood fired pizza for everyone. They had a nice Barrel Vault pizza oven outside that someone built. He sent me some pictures. Right away I could tell that it wasn't built right and it didn't look like the material was proper.

After cooking the pizza, my brother said that they had to take them inside to finish them. The problem they had was that the Bottom of the pizza would not cook in the proper fashion as the top was cooking. This meant that the oven floor wasn't hot enough. I could tell by looking that it didn't look like they had insulated properly. Of course I really didn't know what was under the floor but after hearing how they had to cook pizza, it was clear what was wrong. Floor was wicking heat and not getting hot.

So the reason to type all this, as I cook in the oven I just finished, I am amazed in it's performance already. I would have really regretted cutting certain corners if my performance was affected. (There were some corners that I cut)

So if you can recover from this really easily, do it.
But if it is done? I am with Cobblerdave - try it out and run with it. You can always build another.

D

[stonecutter]

Re: How bad did I screw up? Used the wrong mortar

G'day
I can't understand how poor these red common bricks can be? There's an old brick oven near where I live in Manly, the old Greek who owned the store closed it about 15 years ago . I saw the oven in the yard when my boss was making a quote for a job just after it closed . Of course I didn't know what the little niceties that I was looking at then but I can tell you it was built of the light red commons that were used in the 50s and 60s. I notice them because there very common on buildings such as public buildings and churches every thing else from that era is built of hardwood. The oven was old painted with mutliple coats of white paint and the thing that I noticed that the hearth bricks were worn down badly over the years if use. That oven had survived quite a bit of use and it wasn't falling apart it was just plain worn.
Firebrick isn't common in Australia apart from the capital cities so there a lot of ovens built of clay brick commons and pressed clay pavers. They mightn't last forever but they are worth the effort to build cause they still work.
I still say put a fire in that puppy and see if it works even if its not insulated it will still work. Insulating materials like pearlite and CF are modern materials anyway and these are very old type ovens.
Sorry stonecutter I'm a very " make do" kinda person and I think its a crime not to at least put some fire in that thing. If he is willing to pull it down anyway why not.
As always
Regards dave

No need for apologies, this is what the forum is for. If everyone agreed all the time that means we know it all (not possible) or don't want to learn.

When people come here and post the kind of questions like the OP, I feel they should get the full scope and consequences of what they are doing. This isn't doom and gloom, it's reality. I did say at the end of my post (in different words) that making due is an option.

For one thing, you don't know how these red 'commons' are going to respond to oven use.....they vary in composition and hardness too much to make a sweeping endorsement based on a couple examples. Some clay is loaded with silicate and will hold up well to thermal cycling, but you can't tell with your naked eye. Still,others may be poorly fired with low quality clay. You can have one 'common' red may hold up long term, and another will crumble apart under stress. They are designed to be used as building units, not oven thermal mass.

Another thing you may have overlooked is climate. Illinois is not Australia, it's not the tropics or sub tropics. Not everyone shuts their oven down for winter, but with brick like that you better. Once you start making compromises like using material that isn't suited for the project, you start placing limits on whatever it is you built.

See, this is in the interest of full disclosure, not push certain material. And as far as using what you have and can do attitude, I think I understand that well. My current oven is mostly comprised of materials I had laying around....the granite was even dragging 860 miles here after one of my projects. But I didn't take chances on the oven itself by using the Charleston Greys I had, just because they may work.

IF the OP wants to roll the dice on reds he can....and maybe building an oven with Type S and red is all he ( or anyone else) can do, because that's all he has.......that's a different story. I haven't seen enough misapplied masonry material succeed to trust it long term when used incorrectly ( this is different than best practice too) and anecdotal projects don't qualify as examples to me. In fact when you spend years and years fixing other peoples masonry mistakes, it forces you to trust proven methodology, technique and application.

I think the bigger crime would be to invest more time with iffy material, if the op has access to refractory and wants to be assured of quality. Besides, it's an oven dome here, not an Egyptian pyramid.....taking it down ( if he chooses this route) and building it back will teach him WAY more than a one off.

[cobblerdave]

Re: How bad did I screw up? Used the wrong mortar

G'day
I can't understand how poor these red common bricks can be? There's an old brick oven near where I live in Manly, the old Greek who owned the store closed it about 15 years ago . I saw the oven in the yard when my boss was making a quote for a job just after it closed . Of course I didn't know what the little niceties that I was looking at then but I can tell you it was built of the light red commons that were used in the 50s and 60s. I notice them because there very common on buildings such as public buildings and churches every thing else from that era is built of hardwood. The oven was old painted with mutliple coats of white paint and the thing that I noticed that the hearth bricks were worn down badly over the years if use. That oven had survived quite a bit of use and it wasn't falling apart it was just plain worn.
Firebrick isn't common in Australia apart from the capital cities so there a lot of ovens built of clay brick commons and pressed clay pavers. They mightn't last forever but they are worth the effort to build cause they still work.
I still say put a fire in that puppy and see if it works even if its not insulated it will still work. Insulating materials like pearlite and CF are modern materials anyway and these are very old type ovens.
Sorry stonecutter I'm a very " make do" kinda person and I think its a crime not to at least put some fire in that thing. If he is willing to pull it down anyway why not.
As always
Regards dave

[Gulf]

Re: How bad did I screw up? Used the wrong mortar

I hope that the insulation under your floor is up to spec. If so, or close:

Build your enclosure in such a way that it can be dissassemled. A simple roof over, or making it a doggie house style, out of roofing metal with screws would help. Building it in such a way will allow you to recover all of your dome insulation.

You could spend the time (maybe years) before it fails, cooking and gathering up the "best practice consruction materials" .

[Novaslo]

Re: How bad did I screw up? Used the wrong mortar

I just spent 3 months on my build. I cooked in it on Sunday for the Maiden Voyage. I have dreamed about the damn thing many times.....

However, last night....I dreamed that it crumbled....unfortunately, you will likely dream that as well.
Good luck.

[stonecutter]

Re: How bad did I screw up? Used the wrong mortar

I'll be the party pooper. This is far from best practice....it's not even good practice.

Type S mortar is going to be a problem relatively fast. I've repaired several fireboxes built with it and fireplaces operate at half the temperatures as ovens do. It's a building mortar yes, but definitely not good for oven building. You need at the very least, a mortar with fire clay in it.

As for the red brick, thats not the best choice either. And depending on how it was made ( tons of variables here ) it may last years, or it may last months.

Ask yourself, are you ready to start over and rebuild within a year? Because that's a very,very real possibility. And with being surrounded by an enclosure, you're looking at more re-building too...because you'll have to take some or all of it apart to rebuilt the dome.

If you have no choice of material, can't get anything else or you don't care, then keep on building. If not, you should reconsider continuing with these materials before you get further. It s not like you have to waste any of it....use the red brick for veneer, and the type S to set it.

[cobblerdave]

Re: How bad did I screw up? Used the wrong mortar

G'day
Don't just tear it down because it doesn't meet " best practice".
There heaps of ovens that don't contain firebrick. A domes are pretty strong structure due to its shape, gravity holds the bricks together the mortar only holds them into position .
You can tear that thing down anytime so why not use now and enjoy it first.
Give it a go,
Regards dave
Ps give us an update on how it works For You. I wouldn't be surprised if it works quite fine

[boerwarrior]

Re: How bad did I screw up? Used the wrong mortar

Hi there!

wow, tough question. I think the answer is: it depends!

I think we need more data to help you answer your question:

1) Except for the Type S mortar and red brick is your oven built following the plans on this site? I.e. is your oven extremely well insulated especially under the floor? Is your foundation rock solid and built using reinforced concrete? Are the joints tight especially on the interior?
2) How much time do you have in your build?
3) How will you use your oven? Occasional family get together's or frequent large pizza parties?

My thinking is: If your oven is essentially perfectly built with the exception of the mortar and firebrick, and if you won't use it every day, then I would go ahead and finish it and use it. If it is well built and the joints are not very large then it will not fall down. If you cut corners elsewhere as well as on the mortar and brick, and if you want to use the oven regularly, then consider this a learning experience and rebuild it.

Just my $0.02-. I'm sure others will weigh in too!

Neil

[Old_haidouk]

So embarrassed to admit but my first 36" Pompeii didn't go as planned... All was well until building the dome. Trying to save $$$ I used type S masonry mortar for the dome. Also red bricks not firebricks. Is this thing gonna collapse on me? Should I tare it down and use the proper fireclay mix or refractory mortar? I plan on enclosing the dome in a square house to match the base. TIA