Firebricks and frost

[daveuk]

I have just finished dismanteling my Earthstone oven when its pre-cast lining failed.  It was first fired in 2012 during the Olympics.

I'm planning to use the existing plinth to support a brick-built Naples-style oven.  The tunnel entrance will be made from the same firebrick as the oven, but I'm concerned about possible frost damage.  Firebrick is usually pretty porous, so the tunnel mouth will inevitably get rained on.  I could put a granite landing stage to extend a little way in, rather than firebrick floor all the way to the front, but does anyone have any feel for the sort of temperature gradient that a brick-and-a-half tunnel will see?  If I run the granite in by, say, 75 - 100mm, I can add a wooden outer door to keep the worst of the weather off and put facia tiles on the front of the arch.

Any thoughts would be gratefully received before I finalise my design.

[downunderdave]

Nov 16, 2021 16:03:25 GMT daveuk said:

I have just finished dismanteling my Earthstone oven when its pre-cast lining failed.  It was first fired in 2012 during the Olympics.

I'm planning to use the existing plinth to support a brick-built Naples-style oven.  The tunnel entrance will be made from the same firebrick as the oven, but I'm concerned about possible frost damage.  Firebrick is usually pretty porous, so the tunnel mouth will inevitably get rained on.  I could put a granite landing stage to extend a little way in, rather than firebrick floor all the way to the front, but does anyone have any feel for the sort of temperature gradient that a brick-and-a-half tunnel will see?  If I run the granite in by, say, 75 - 100mm, I can add a wooden outer door to keep the worst of the weather off and put facia tiles on the front of the arch.

Any thoughts would be gratefully received before I finalise my design.

You do what you can get away with, but granite has the reputation for not liking heat.

[awalker]

I agree had a granite slab in my previous clay oven for the floor. It cracked after the first few firings. When i took the oven apart it had too many cracks in it to count.