Discussion
Hi all, need a bit of guidance on grout. I have a boxed in section (MDF) which is around some pipes and the whole of this has been tiled. The tiles and grout seem to be coming away and the grout is crumbling out. I have assumed that this is because the pipes behind are hot central heating pipes as this is not happening anywhere else in the kitchen.
My question is, is there any special type of grout that is made for this, that can withstand "heat"?
Sorry for the rambling post
Cheers
Steve
My question is, is there any special type of grout that is made for this, that can withstand "heat"?
Sorry for the rambling post
Cheers
Steve
Did you treat the MDF with diluted PVA before applying the adhesive? I've got a number of boxed in/tiled over area in my house, but I always put PVA on first (then apply the adhesive when the PVA is still tacky).
Actually thinking about it, I probably used WBP rather than MDF, but maybe part of the issue is the heat. Though I have some tiling over the pipes immediately under my boiler and they get really hot, but there might be an inch or two of air space between the pipes and the plywood.
Actually thinking about it, I probably used WBP rather than MDF, but maybe part of the issue is the heat. Though I have some tiling over the pipes immediately under my boiler and they get really hot, but there might be an inch or two of air space between the pipes and the plywood.
you should not tile on mdf and you should never use PVA either.
you need to either over ply or backer board the box work.
if you do need to create a bond use bal apd,but definitely not PVA ever
you need a 2 pt flex adhesive if use choose wood or normal tubbed adhesive if you use backer board or similar.
2pt flex is very expensive and you dont really need a lot but you will have to buy quite a big bag.
i would use backer board or similar and screw to the mdf,then just use normal tubbed adhesive.
its not the heat thats the problem it the mdf.
you need to either over ply or backer board the box work.
if you do need to create a bond use bal apd,but definitely not PVA ever
you need a 2 pt flex adhesive if use choose wood or normal tubbed adhesive if you use backer board or similar.
2pt flex is very expensive and you dont really need a lot but you will have to buy quite a big bag.
i would use backer board or similar and screw to the mdf,then just use normal tubbed adhesive.
its not the heat thats the problem it the mdf.
OldSkoolRS said:
Did you treat the MDF with diluted PVA before applying the adhesive? I've got a number of boxed in/tiled over area in my house, but I always put PVA on first (then apply the adhesive when the PVA is still tacky).
Actually thinking about it, I probably used WBP rather than MDF, but maybe part of the issue is the heat. Though I have some tiling over the pipes immediately under my boiler and they get really hot, but there might be an inch or two of air space between the pipes and the plywood.
NEVER use PVA unless the adhesive manufacturer specifically recommends it. Actually thinking about it, I probably used WBP rather than MDF, but maybe part of the issue is the heat. Though I have some tiling over the pipes immediately under my boiler and they get really hot, but there might be an inch or two of air space between the pipes and the plywood.
Dr_Gonzo said:
OldSkoolRS said:
Did you treat the MDF with diluted PVA before applying the adhesive? I've got a number of boxed in/tiled over area in my house, but I always put PVA on first (then apply the adhesive when the PVA is still tacky).
Actually thinking about it, I probably used WBP rather than MDF, but maybe part of the issue is the heat. Though I have some tiling over the pipes immediately under my boiler and they get really hot, but there might be an inch or two of air space between the pipes and the plywood.
NEVER use PVA unless the adhesive manufacturer specifically recommends it. Actually thinking about it, I probably used WBP rather than MDF, but maybe part of the issue is the heat. Though I have some tiling over the pipes immediately under my boiler and they get really hot, but there might be an inch or two of air space between the pipes and the plywood.
, so I hope my tiles don't start falling off now, though some of them have been up over five years so maybe the adhesive I used was OK with PVA (I know I wouldn't have checked though).OldSkoolRS said:
I've tiled numberous rooms in my house including 10mm thick travertine on walls and floor. I thought it was good pratice to use PVA before applying the adhesive , so I hope my tiles don't start falling off now, though some of them have been up over five years so maybe the adhesive I used was OK with PVA (I know I wouldn't have checked though).
My tile supplier recommended BAL Prime APD, and with possibly 1/4 ton of travertine poised to fall on me whilst in the bath, I did what they said! , so I hope my tiles don't start falling off now, though some of them have been up over five years so maybe the adhesive I used was OK with PVA (I know I wouldn't have checked though).If my supplier had recommended a primer or BAL, then I would have listened, but he didn't (only selling me the flexible adhesive, grout and sealant for the travertine), hence why I thought it was standard practice to use PVA.......I guess you live and learn.
I put the travertine up last year and it seems to be holding up fine; I was more concerned with the floor as this was the first time I'd tiled on wood (18mm WPB in place of floorboards). So far no cracks in the grout or signs of movement though I put about a million screws and extra noggings between the joists to strenghten.
I put the travertine up last year and it seems to be holding up fine; I was more concerned with the floor as this was the first time I'd tiled on wood (18mm WPB in place of floorboards). So far no cracks in the grout or signs of movement though I put about a million screws and extra noggings between the joists to strenghten.
The simple answer is normal PVA isn't waterproof - hence if you tile a steamy bathroom that's been pva'd then there's a very real chance the pva will just peal off the wall...
Obviously waterproof PVAs are available that are far beeter, or a proper sealant.
MDF is pretty nasty though, the minute any water gets in the edge it will blow up like a tampon in a river.
Obviously waterproof PVAs are available that are far beeter, or a proper sealant.
MDF is pretty nasty though, the minute any water gets in the edge it will blow up like a tampon in a river.
OldSkoolRS said:
Yes, that all makes sense...hopefully they'll stay on now (I don't think the steam could get 'under' my tiles anyway now they are sealed), at least I used WBP and not MDF (that was the OP's boxing in).
Well the steam was more a reference to the humid environment. Probably okay as long as the grout isn't constantly wet.ive been tiling for 30 odd years and there is a lot of bulls
t involved nowadays but the pva one make sense,basically it creates a barrier,you are stuck to one side and the other side is stuck to the wall,so not much holding it all up.
also pva or wood glue reactivates when made wet ie: applying adhesive which is wet can reactivate it causing the tiles to not set correctly.
having said all that i used pva for over 20 years and only had a few problems these were mainly down to reacting with certain chemicals in some plaster.
plaster board, render,backer board and plaster do not generally need sealing unless you intend to use powder adhesive on plaster,which should then be treated with whatever is recommended by the adhesive company you intend to use,but generally its apd.
feel free to pm me if anyone needs to ask any questions about tiling.
t involved nowadays but the pva one make sense,basically it creates a barrier,you are stuck to one side and the other side is stuck to the wall,so not much holding it all up.also pva or wood glue reactivates when made wet ie: applying adhesive which is wet can reactivate it causing the tiles to not set correctly.
having said all that i used pva for over 20 years and only had a few problems these were mainly down to reacting with certain chemicals in some plaster.
plaster board, render,backer board and plaster do not generally need sealing unless you intend to use powder adhesive on plaster,which should then be treated with whatever is recommended by the adhesive company you intend to use,but generally its apd.
feel free to pm me if anyone needs to ask any questions about tiling.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff