More questions for experts.

[msylt]

I am building a domed 42 in oven in SW Minnesota. Kind of time-restrained so I am working as fast and efficiently as possible. The 2 inch FB insulation board beneath the floor has gotten wet in areas. Will that be a problem or will it dry out with the first firings? I'm going mostly by the e-book plans. The plans call for 3 in of blanket insulation over the dome and then chicken wire, finishing with stucco. Is that going to work well or is it recommended now to add perlite/concrete in an added layer?? My last question deals with the structure that will be supporting the chimney. I obtained an 8 by 8 flue liner thats about 24 in long. I plan on mounting that on the arch. I included photos. Whats your opinion(s) on the strength of this arch to hold up the liner which is fairly heavy..maybe 35 or more lbs? The opening on top is the same size as the outside dimensions of the liner, with the 2 middle arch bricks bearing all of the weight. The 2 support bricks are positioned at an angle consistent with the arch angle. Any suggestions. Do you think the 2 bricks will hold it up or do I need more support here? Thank you in advance!

[jbruning]

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The opening on top is the same size as the outside dimensions of the liner, with the 2 middle arch bricks bearing all of the weight. The 2 support bricks are positioned at an angle consistent with the arch angle. Any suggestions. Do you think the 2 bricks will hold it up or do I need more support here? Thank you in advance!

Not an expert, but are the two bricks you are talking about 'hanging' on the mortar or are they integrated in the arch? The two on either side of the opening appear to not be integrated in the arch and if this is the case I would be concerned of them dropping. What is holding them in place?

[stonecutter]

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The 2 support bricks are positioned at an angle consistent with the arch angle. Any suggestions. Do you think the 2 bricks will hold it up or do I need more support here? Thank you in advance!

You should change the last brick before the opening to a whole brick..good question below...

The two on either side of the opening appear to not be integrated in the arch and if this is the case I would be concerned of them dropping. What is holding them in place?

That is the problem. The downward pressure applied by your flue on an independent brick could cause an arch failure, or at the very least, cause the angled brick to slide out. Realizing your oven arch and opening arch carry some of the weight from above, you still need the vent to take the pressure that is applied. By using a whole brick, the downward pressure is transferred into the walls of the vent.

Also, keep load bearing masonry (like your flue support) at right angles. Angling the brick isn't the way to transfer weight laterally, unless you have a continuous line of masonry units or stone.


I must ask...are you mortaring the bricks together with material mixed with perlite? It sure looks that way in the pictures.

[V-wiz]

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The insulation is fine it will dry, also the blanket insulation and stucco is also fine. I put 6 inches on mine and chicken wire and stucco. Find my post and check it out.

[msylt]

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Thanks to all 3 of you for replying! John, The bricks are all part of the arch. It is a bit over 18 inches in width, 2 bricks, with tie-in up to the chimney opening. But the load will be on 2 single bricks. How about if I lay 2 bricks perpendicular to the arch, on each side with a brick on each side perpendicular to that, notching them so that there is equal pressure on all four sides? Setting the flue down on the notched bricks and mortaring them in. Bec, would that evenly distribute the load enough??
__ __ Such as that crude diagram, sorry, no good artwork here. Is 3 inches enough, V?
I I
__ __

[msylt]

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Naturally, the diagram did not post as was intended. But the 2 top and 2 bottom bricks would extend over the single middle brick on each side and the opposing bricks would help carry the load. I'm no engineer, but this seems workable, doesn't it?? I just don't want a structural failure. The mortar is made by Alsey. It is called Hi Cast and has a decent amount of aggregate in it.

[msylt]

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2 more photos, may help!

[msylt]

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Also, more quest, lol. What kind of fastener is generally used to secure the blanket insulation and/or the chicken wire to the dome?? Also, does muriatic acid do a good job at taking off dried interior mortar?? Thanks!!

Mark

[jbruning]

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I'm having a hard time telling where the joints are. For the two bricks in question, are the ends between the oven opening arch and also the outer arch? Or is one end integrated into one of the arches, and therefor under a compression load?

[msylt]

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There is a half brick on either side of the middle bricks. What is binding the middle bricks are the back side and 2 ends

[stonecutter]

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Also, does muriatic acid do a good job at taking off dried interior mortar?? Thanks!!

Mark

Acid will attack the mortar in the joints as much as the smudges and the proper way to work with it is to flood the masonry so it doesn't draw the acid in....and more water in the masonry isn't what you want. Plus, using acid in a confined space it is more dangerous. Sponge and/or brush the mortar off at the end of the day to keep it clean as you build. For the staining that is on there, wire brush and elbow grease.

[msylt]

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Thank you!

[stonecutter]

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Naturally, the diagram did not post as was intended. But the 2 top and 2 bottom bricks would extend over the single middle brick on each side and the opposing bricks would help carry the load. I'm no engineer, but this seems workable, doesn't it?? I just don't want a structural failure. The mortar is made by Alsey. It is called Hi Cast and has a decent amount of aggregate in it.

So, you are spanning the angled brick with the notched brick, and these will rest on the arches for the oven opening and vent? That works for carring the weight, but that angled brick is still 100% reliant on the mortar bond to stay put.

You used a bagged castable refractory to mortar your dome together? Interesting to see how that works out. Knowing what it is, you will have to really put some effort into cleaning off those stains.