Fitting Granite Hearth and Limestone Fire Chamber - Expansion Gaps

[benben5555]

Hi guys,

 

We are fitting a granite hearth and a limestone fire chamber. I understand its a good idea to leave expansion gaps between the different pieces. The limestone back is in two pieces and the hearth is in two pieces. What have other people done with the gaps? I was planning on a 2/3mm gap between the pieces, but would prefer to seal with a high temperature sealant. Is this a good idea?

 

Also fitting a limestone fire surround. Similar question, ive seen these with dry gaps between the legs and the header, but is there an alternative? I was thinking to maybe put a 2/3mm metal packer in between the pieces and then grout the gap to get a neater finish.

 

Any thoughts, or ideally photos welcome.

 

Thanks

[Temp]

I can't quite visualise what you are building but check building regs. They require quite a deep (thick) "constructional hearth" if the fire pit/basket/chamber is capable of raising the temperature of the hearth over 100C.  

 

For sealing joints perhaps fire cement? Not sure what colours it comes in but try screwfix/toolstation web sites.