Massive Error - What options do I have?

[Julison]

Hi,

I don't know what I was thinking but clearly I need to pay better attention to the instructions.
I am 3 courses up and I noticed that I have been laying my bricks in the incorrect orientation.
Instead of laying the bricks such that the wall is 4.5" thick, I have been laying them so that each course is 4.5" high.
Don't ask - I have no idea how I came to do this - I have looked at a million pictures and it just dawned on me tonight as I started the fourth course that something didn't look right.

What are the implications if I continue with this method?
What are my options?
I'd rather not knock it down clean the bricks and start again but if that is the only option, tomorrow will be a rough day.

thanks

[Julison]

Well, I’ve thought of options. I’ve decided not to say art again. I will either continue as is and be the owner of a fast heating pizza oven (the walls would be the same thickness as the floor) or I could switch to laying the blocks in the correct orientation from here on out. Not sure of the impact on overall strength. It will look relatively normal from the inside; the outside will all be covered under insulation and v-crete etc. Any feedback on which option will likely provide an oven that is functional over the long run would be appreciated.”

[UtahBeehiver]

A couple observations, The joints of the course are lining up, they should be staggered or the strength of the dome is compromised. Second, as you go up you will have to adjust the width of the brick in order to make the tighter radius of the upper courses. To give you more thermal mass on the dome, you can render the outside of the dome with some home brew mortar then insulate.

[Julison]

Thanks Russell. I was starting each course with alternating 1/4 brick and 1/2 brick to avoid having seams lining up but it "seems" that at various points in the course they do eventually line up again and then separate later again in the same row. I guess I need to insert 1/4 bricks mid course. Do you know if anyone has built an oven with the bricks oriented as I have - is there enough lateral strength with the bricks on edge instead of on the flat? At this point I think I will resort to the standard orientation for all future courses and in that way create an oven that will have the lower 1/5 (floor and first three courses) with lower thermal mass and the upper 4/5ths std. It may result in an over that heats more uniformly given that most of the BTUs are initially directed to the upper dome. Trying to make a good news story here....

[UtahBeehiver]

There have been a couple, I believe one in Australia with no reports on any issues but many builders do not post problems or failures though. I am not sure if the difference in wall thickness from the lower course to the upper courses will cause an uneven expansion issue.where the lower course saturate and heat up faster than the thicker upper courses. If you go this direction you still may have to add some thermal mass on the lower courses Just thinking it through.

[SableSprings]

I agree with Russell, that the uneven expansion issue would be the primary concern with making a "thicker dome cap" on your oven. With the alignment of your brick joints, the probability of cracks in the future is pretty high. The good news is that the dome structure will tolerate such minor cracks...in Italy, many of the old time ovens and bakers in fact use the width of the cracks to determine the temperature of the oven. I have a crack in my oven that follows an alignment. When the oven is hot, the crack is larger but as the oven cools the crack diminishes to its "normal" width. The people that have cast their ovens usually shoot for 2"-3" (50-75 mm) thickness in their dome, so although your brick orientation is different, it is not wrong ... just different Do work on avoiding the alignment from here out. Also, you will want to look at tapering your bricks as you go up the dome so the gaps are minimized.

Having an oven with this thickness means it will heat up more quickly, but you will not have huge heat storage to expect cooking/baking temps for days after a firing. As Russell also noted, you can add mass with a home brew coating on the outside of your dome bricks...but you'll still be able to do pizza and later bake bread with what you've got going...so relax, don't worry. If you are looking at baking 20-30 loaves of bread on bake day, I'd consider the extra mass. If you are just looking at pizza and some bread/meat roasts, you're golden.

[Julison]

Thanks for the advice Mike and Russell. Snow is coming so I didn’t have much time. I decided to switch brick orientation for the remainder of the courses. It looks funny - made my kids laugh.... I need to check if I need to buy more used brick now that my design has changed. Thanks again for your advice, very much appreciated.

[wotavidone]

I own the Australian oven.
https://community.fornobravo.com/for...428#post404428

I built an oven with bricks laid like yours. Mine were only 2 inches thick. It works well, but I do sometimes wish for more thermal mass and better insulation.
Your bricks look thicker than 2 inches?

[mrpubnight]

Would it not work to just add splits or off cuts to make up the thermal mass? Seems to me that as long as you don't have a big difference between the top and bottom you won't have too much of a temperature gradient.

Thoughts for more senior builders?

[Karyn B]

I defer to Russell but what about doubling your lower courses by laying "a double coat" in the same orientation? That way, it may help strengthen your lower oven to securely support your correct orientation upper portion? Otherwise, it seems dicey in strength. I know Russell advised me to support my soldier course as the outward pressure could compromise the strength. Just saying. I would hate to see you start over. Maybe it would work. What's you think Russell?

[mongota]

If it was mine, because I want the thermal mass of a thicker dome, I'd break it down and start over. Sounds horrible, but any residual mortar on the bricks will clean up in no time at all using a diamond blade on an angle grinder. It'd only take a few hours to be back to square one.

You can certainly continue with what you have, just make sure it's what you want. Going backwards can actually be a step forward for getting the oven that you wanted in the first place. It won't be a setback. It'll simply be fixing a mistake. A setback would be continuing to build a design that doesn't suit your cooking needs and then trying to modify it with render coats or another layer of splits, or adding extra insulation, in order to HOPEFULLY get the thermal performance of your original design.

If you don't need the thermal mass, onward and upward!

But by all means, get the oven that you want. You're still so early in the build.

Best, Mongo

[Julison]

thanks all. My thought at this point is that I will use the correct orientation for the remaining courses. It should heat up more evenly given that the 4.5" courses have more thermal mass but will get the most heat being on the top 1/2 of the oven and having more direct flame contact and will benefit from the convection. On the lower half with the bricks 2.5" they will have less thermal mass and would heat likely at the same rate as the top of the oven because they get less direct heat. I'm love expts. A bigger thermal mass is great if you are looking to get a lot cooked with a single firing - I doubt I will be in that position.
My biggest concern at this point is winter. I got set back a couple weeks when we had a big tornado come through town in late Sept and now it's sub zero at night. I am looking to build a temporary tent to heat and allow me to get done. thanks again all. I will post pics as I move forward

[deejayoh]

not sure I agree that the lower half is exposed to less heat. you'll be banking your fire up against the sides, so there is plenty of heat. Personally, I'd knock it down and clean up the bricks with cold chisel. The bottom courses are the easy ones anyway.

I would worry about the strength of the dome at the point of the change in brick size. The load of an arch is carried outward along the curve of the arch to the base. You've got an uneven load bearing path. Not sure what the consequences might be.

[Julison]

I'll keep you posted.

[Julison]

I got to admit, it looks a little funny from the outside. A little like an acorn.