Fire proof adhesive failing on chimney breast

[Stuart L]

Hi

I'm looking for some advice. About 4 years ago a tiled a chimney breast with 600 x 600 stone tiles. Since then I have had repeated failures were i have had to remove the tiles and reapply them.

The story is kind of long and I will try to provide as much detail as possible.

The Chimney breast as been fitted with a wood burning inset fire . The original plaster was all removed and all 3 sides lined with fire board (dot n dab plus concrete screws on 600 centres). The stone tiles are polished London grey and were fitted using vitcas fireproof adhesive and grout.

After the 1st winter i noticed the tiles coming away. So removed them before they fell off.

At this point I noticed that my original coverage of adhesive wasn't as good as it could be, about 50% of the rear of the tile actually touching adhesive (about what you'd expect from an amateur).

I replaced the tiles taking more care with the adhesive coverage again using vitcas products.

Another winter of fires and I noticed that the large tile directly above the fire was starting to come away. I duly removed this tile, I noticed at this point that the adhesive was stuck to the fire board and the rear of the tile was pretty clean. I therefore attacked the the rear of the tile with an angle grinder roughing the polished stone to provide a better key. Again I reapplied this tile using vitcas products

I thought this had cured the problem, however 2 years later and i have just noticed the tiles immediately adjacent to the fire starting to come away again.

I knew this was going to be difficult when i attempted it 4 years ago. (tiles within 1" of the fire, expansion etc) but the management as seen loads of glossy pics of landscape inset fires with fully tiled chimney breasts and I agreed to try it for an easy life.

I'm now starting to lose faith in vitcas, but am not sure how to prevent this happening again in the future.

Any advise will be greatly appreciated.

 

[WetSaw]

Are you back buttering the tiles as well as trowelling the wall?

 

[Stuart L]

Are you back buttering the tiles as well as trowelling the wall?

yes. Working the tiles down in shuffling motion to get them level. I know my coverage on the 2nd attempt was a lot better

 

[LM]

Without knowing what type of ‘fire board’ you’ve fitted and have never heard of ‘Victus’ adhesive I would suggest that providing the fire board you have is suitable forbtiling that you prime it, back butter your tiles and use an adhesive like the one from the link I’ll provide below and follow the instructions as to allowing the adhesive to cure properly before you introduce it to heat.
ISOMAT AK-FIRE - Adhesives for Special Applications, Tile Adhesives & Grouts - ISOMAT - https://www.isomat.eu/product/isomat-ak-fire-2-en/

 

[Stuart L]

Lee
the adhesive I used is "vitcas" link below

HB60-HYDRAULIC BONDED ADHESIVE - https://shop.vitcas.com/hb60-hydraulic-bonded-adhesive.html?gclid=EAIaIQobChMIjobH1K6S2gIVLLHtCh26tApsEAQYBCABEgK4-vD_BwE

I was led to believe that its specifically formulated for the type of job i was doing.

looking at the Isomat product , it says its a refractory cement suitable for fire bricks, would this be suitable for tiling?

 

[LM]

Tbh there’s too many variables now, you started off saying that you’d 600 x 600 ‘stone’ tiles and then you said you’d attacked the “polished stone” with a grinder to give it key.
We still don’t know the exact type of fire board in place and as I said I’ve never heard of Vitcus adhesive and the picture of what loooks like a dispersion type adhesive as above doesn’t give me much hope. Is it a cemitisious type adhesive ?

 

[jobdone]

I think you should change the adhesive. The method attached to the link you posted states to use PVA to prime surfaces. That is a massive No No and could be leading to your failure.

 

[Stuart L]

Lee
both sides of the stone tiles were polished. This is why I roughed the reverse side up before reattaching the tiles.
Unfortunately I don't know the make of the fire board as it was installed by my fire place installers. (didn't want to mess with carbon monoxide, i will take on most things but draw the line at that). They assured me it was the right stuff for the job. Went up like dry lining (dot and dab) additional concrete screws inserted following day after adhesive had dried.

Jobdone
You are correct I did follow the instructions and used PVA. Why is this a problem?
What should I have used?
Also what adhesive and grout do you recommend? Baring in mind the tiles immediately above the fire are getting too hot to touch, so i'm assuming they are around 50 degrees C plus

thanks in advance.

 

[WetSaw]

Can you post a few pictures? Showing the whole chimney and stove not just close up.

 

[Stuart L]

pdc
photo attached

 

[WetSaw]

They look like porcelain tiles, have you got a picture of the back of one?

 

[Stuart L]

pdc
the "tile" is a polished sandstone I got from a company called mandarin stone. They don't appear to stock the polished version anymore just the tumbled.
Luckily I had some off cuts, photos show both sides of same tile.

 

[Stuart L]

Sorry should have said "polished limestone"...lol