Slip Joint or not?

[bricks]

Hi Out there,

I will be building an outer arch out of Bullnose bricks 9". I'm leaving the half bricks out to create a toothing which will be filled with 3" of blanket 1" of vermiculite/fondu then 3/4" of render 41/2" of the Facade bricks will overlap 41/2" of the firebrick inner arch should this overlap be a slip joint would appreciate any thoughts.Bricks

[brickie in oz]

The outer arch looks from the pic like it will be in contact with the heat and flames?
If so it will crack with the heating and cooling cycle.

[bricks]

Hi Bricky in Oz,
I'm thinking the same. Perhaps a 5mm gap between the to arches as both are selfsuporting.Or because its the furtherist from the fire a bed of fire clay or ramming puttey between the two could work.bricks

[brickie in oz]

Originally Posted by bricks

a bed of fire clay or ramming puttey between the two could work.bricks

Or some ceramic rope?

[david s]

About 6:1 vermicrete will work well too.

[bricks]

Thanks for the info David S.Does this mix have normal cement or fondue. Bricks

[bricks]

Hi Bricky in Oz,
Just thinking that if i cut a channel into the internal and external bricksto take the rope it would act as an anchor and a great seal still allowing say a3mm gap to difuse heat transfer to the facade. Bricks

[david s]

Originally Posted by bricks

Thanks for the info David S.Does this mix have normal cement or fondue. Bricks

I just use Portland. It is in a slightly cooler area and seems to work ok. Fondue is a bit of an overkill IMO when used outside the main oven. It is also way more expensive.