Expanding Foam near fireplace!?

[Robbie010]

I have a little issue with a new log burner installation.

I plan to line the chimney chamber and the wall either side of the opening with 6mm cement board before tiling. However, the bricks on front corners of the fire have been broken and chipped away quite badly, so I need to fill the gap where the cement board will meet in order to give it some strength / support.

For ease, I was hoping to use an expanding foam but after doing a little reading I’m not sure….

I know the surfaces surrounding the fire will get hot but I’m not sure how hot! The side walls of the chamber will be around 200mm away from the side walls of the log burner and obviously, the expanding foam would be beyond the cement board and tiles..

Is there such a thing as fireproof / heat proof expanding foam for this kind of application?

Thanks.

 

[George_engineer]

Use plasterboard adhesive with a few mechanical fixings.

Behind cement board at 200mm away won't get very hot but I don't think foams would be very reliable in those conditions.

 

[noseall]

Is there such a thing as fireproof / heat proof expanding foam for this kind of application?

Yes. Use the (red) fire-foam. If applying to surfaces where gravity is a problem, damp down the area first with a spray bottle, or some such. Lay some newspaper down to collect any droppage.