Firebrick mortar

[Dave Sickles]

I'm building a barrel type oven and as the brick starts to arch the mortar joint gets quite large,what is the best mortar to use

[SableSprings]

Many of the builders here end up using what we call "homebrew" mortar for these ovens. The formula is 3:1:1:1 by volume (fine sand:builders lime:fire clay:cement) and is one of the least expensive ways to go...certainly as compared to some of the pre-mixed refractory mortars on the market. The biggest issue in the past for those new to brick & mortar work is finding the builders lime (hydrated lime...not the type used in agriculture!) You'll find that the homebrew is pretty easy to mix, great to work with, can be used to fill fairly large gaps, and bonds very well to firebricks. The "big/thick" joints of homebrew will become added mass for your oven (and you won't have to do any extra brick trimming for a tighter fit on each arch of the vault).

Remember that you want to put adequate insulation both below your firebrick cooking floor and over the vault...not having adequate insulation is the #1 reason for ovens that don't perform up to their owner's expectations. You want 2"-4" of ceramic board (or equivalent) underneath and 2"-6" ceramic batting over the top (and back wall). Also, be aware that you will need to add buttressing to your build's sides as the vault (half-barrel) structure creates outward thrust. Hope that helps!

[UtahBeehiver]

We do not see a lot of barrels ovens on this forum but I do recall there was lengthy discussions on the end walls of the barrel. My recollection was that it was better the have the end walls fit inside the barrel arch vs sitting outside the barrel arch. This was due to the expansion of the brick on the barrel will push out the end walls if they are placed on the outside face of the barrel.

Plus one on Mike's suggestion on homebrew. Fire clay can be problematic, you will not find it at big box stores rather go to a brick mason supplier and get brickies clay, common brand is HC Muddox, fairly cheap.

[Dave Sickles]

Thanks,I got all my material for the homebrew today,even the fire clay..lol...so it's better to fit the end wall in vs laying the brick on the outside?..makes sense to me.

[david s]

Due to the inherent structural instability of the barrel vault, apart from the vault expanding and wanting to push out the end walls it also exerts considerable pressure on the side walls. They either require buttressing/abutment or bracing. Here's a build that used steel bracing that you may find useful. Also search the forum for "barrel vault", you should find plenty more. Although it may seem far simpler to build a barrel arch rather than a dome, it actually proves to be more difficult because of the aforementioned problem.

#1

[Bryanthesnail]

Hi, I am a newby. I want to build a barrel shaped oven, with a connecting section to the cast iron hinged door. This front section would house the flue. I was thinking of building an outer wall and topping with clay tiles. My question is would the wooden battens get too hot, or can i fix the tiles without battens?