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dbhansen 08-19-2008 10:40 AM

Mortar thickness in the arch?
I'm looking for guidance on how thick the mortar joints can or should be on the inner and outer arches, including the arch and the arch wall. Is it always best to taper the arch bricks and keep the joints as thin as possible (so the arches would stay put even if the mortar were removed)? Or is it just as good to use un-tapered bricks and relatively thick mortar joints?

How about in the arch wall (with bricks stacked vertically)? Is a 1/32" joint just as good as 1/4"?

I'm trying to decide whether to taper my outer arch bricks. And it's too late for the rest of it, but I feel like maybe I didn't use enough mortar in my arch walls.


CajunKnight 08-19-2008 06:36 PM

Re: Mortar thickness in the arch?
if you can taper bricks and use just enough mortar to stick bricks would be your best approach. if mortar fails due to heat or elements the taper will keep the arch in place for years to come. i have seen arch work done with no mortar and people have been walking under them for many years. the secret is in the keystone.

just my .02 scents

toddj 08-19-2008 07:05 PM

Re: Mortar thickness in the arch?
From what I know.. an uncut brick can fall out.. if every brick is tapered and you use just a very thin mortar with very small sand, it will be there forever.

I did an arch with just portland and no sand once because the joints were very tight and it was hellastrong...

nissanneill 08-20-2008 03:08 AM

Re: Mortar thickness in the arch?
1 Attachment(s)
the thickness of mortar or adhesive depends upon the type that you are using.
I agree with the others in so far as cutting the bricks to fit properly (or using tapered bricks as I did for both arches - picture)
I used the poor man's mortar and used around a 6-10mm joint, just like in a house wall.
The tapered bricks are self locking in so far as they will drop a little and get tighter within the arch.
If you use refractory adhesive, a limit to the width of the joint is approx 3mm max. If you need a thicker joint, then a different product is required.
That and the cost, put me off those products apart from the fact that the ancient ovens were built without even modern portland cement and they are still standing.
I would cut the bricks and use a 6-10mm joint as they look better and you will be looking at them for years to come.


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