problem with sealing a cottage sauna stove

[sammyd]

I would like to obtain advice on how to go about sealing a sauna stove to a firewall made of cement board.

I have tried seveval products including stove and gasket cement, refractory cement but have had no luck.
These products all contain heat resistant properties but they seem to crack after a few fires.
The gap I am trying to fill is around a half inch between the one quarter inch steel stove and the half inch cement board.

I have also tried to insert in the gap stove gasket material in order to disperse the heat but without any success.

Would someone have any idea as to a product that exists or a solution to this problem.

Thanks

A frustrated cottager

 

[Shane]

There could be movement (metal firebox expanding with heat possibly) that is causing it to crack out. Are they hairline cracks or do chunks of it fall out? Maybe try stuffing insulation in the void and them mortar over that. I've do that on face seal inserts when we clean them. (I know that face seal sucks, dangerous etc. they're grandfather in our area though so all I can do is recommend lining.)