What adhesive for tiling inside fireplace

[AkiraDIY]

I'm wanting to clean up the look of my fireplace before a woodburner gets installed. It's currently some old brick that I've scrubbed as much soot off as I can. A lot of the mortar is missing and the wall very uneven, with dips and missing chunks of brick here and there. So I plan to cover it up with some porcelain tiles but I'm unsure how to prep the surface beyond cleaning and some sort of heat resistant mortar/adhesive (are these the same thing?). I hope someone here can offer some advice.

I'm assuming I'll need to use some mortar to fill in the gaps to create a level surface and let it dry before applying the coat to stick the tiles down. Do I need to seal the brick with anything before doing this?

I'm in the UK, any recommendations on specific products would also be greatly appreciated!

 

[jacko555]

I followed this for the cement board lining

https://www.stovefitterswarehouse.co.uk/pages/lining-a-fireplace

Fitter is happy for me to do those bits and will install stove later in year.

If you want to tile, you tile over the cement board. Links to products in that post.

 

[AkiraDIY]

I know cement board is the faster and easier way to do it in most cases but rendering the wall and tiling over lets me maximise the space of an already small firebox with only a little more effort. Plus, considering how uneven the firebox is and the missing mortar between the bricks, it'll need rendered/repointed to some extent before a backer board can be properly secured, defeating the purpose really.

The current plan is to use BAL Rapid XP Plus tile adhesive to fill in the gaps/bring the surface level (suitable for up to 20mm. Will do in layers where the gaps are deeper), then tile on top. My firebox is around 1.8m2 and a 20kg bag covers 4m2. Should be enough to bring the firebox level and tile.

I've spoken with the installer and he's happy with the choice of materials. The firebox has been scrubbed, washed down, scrubbed again, and hoovered in preparation. And I'll speak to the store assistant about whether or not I need some sort of primer/sealer when picking up the adhesive and tiles.

 

[jacko555]

I think the idea with the cement backer board is to dot and dab, so less effort to bring it level, especially if the substrate is not. It's only 12mm and liberal backend dabs will fill the missing mortar and such.

However your plan seems sound, just a lot more effort, especially if your gaps are greater than 20mm. However if the highest point +12mm is too much space to loose on each side then understandable.

Either way, good luck and share some pics of the progress! Always satisfying

 

[AkiraDIY]

To be honest, I wasn't sure if I could do a liberal dot and dab with cement backer board. I assumed my substrate needed to be reasonably flat so the dabs aren't excessive. Since I need to repoint all the bricks and the BAL rapid plus only comes in 20kg bags, figured it be more cost effective to just render since I don't have any other tiling jobs planned for the time being.

I'll double check the measurements but the firebox is tapered towards the back so the wood burner is going to stick out into the room a little already. If I lose 24mm, it might push the burner out too much. Would 6mm hardiebacker, such as below, be suitable or is 12mm the recommended for a fireplace?

https://www.toppstiles.co.uk/fixing-finishing/preparation/hardiebacker-board/hardiebacker-backerboard-6mm

I'll take some photo's and start a build diary when I get back to it this weekend

 

[jacko555]

Their datasheet only says 12mm for burners

https://www.jameshardie.co.uk/fermacellapi/downloads/file/en-GB/06920000002ikMvAAI

 

[AkiraDIY]

ah, toppstiles data sheet also had it A1 fire rated. Missed the part where it said it was for floors. Thanks

 

[lostinthelight]

If you dot n dab cement boards they needs some mechanical fixings as well

 

[AkiraDIY]

turns out the stove won't stick out as far as I thought it might, so I've went for the cement board option to save me the trouble. Plus I wasn't overly keen on using tile adhesive as render. Felt a bit cowboy/cheap

If you dot n dab cement boards they needs some mechanical fixings as well

If I use mechanical fixings, I take it I'll need metal wall plugs? Also, is there not a risk of cracking the board using mechanical fixings on an uneven wall?

 

[jacko555]

Do it through the dabs. Use a masonry / concrete screw. Non plug needee