tiling over new plaster
- Thread starter helpdad
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Plaster should be dry before it's tiled on mt,
but you shouldn't really tile on backing plasters!
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Have a look at this thread, some good info about tiling on bonding.
//www.diynot.com/forums/viewtopic.php?t=183886
//www.diynot.com/forums/viewtopic.php?t=183886
You cannot tile over Bonding full stop
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rich can he use an acrylic primer to help tileing over gypsum, im haveing a guess that hes useing cement based adhesive??
[quote="jrplastering";p="1972252"]rich can he use an acrylic primer to help tileing over gypsum, im haveing a guess that hes useing cement based adhesive??[/quote]
Interesting! Is that possible, it would save some greif?
Interesting! Is that possible, it would save some greif?
dnt get me wrong you still should not tile over bonding im just thinking outside the box of a way to save you the agro.
Ah. I think I understand exactly where you are going with this, Richard. They are 7mm ceramics, 300 x 400. I've been googling, and discovered the max is 20Kg/mtr sq., . It is actually my son that is doing his house up, and I just get called upon. (Oddly, the 2 plasterers we spoke to didn't mention the bonding problem, it occurred to me that we would have to wait some time for it to dry properly). He has weighed thme, and a metre is 15Kg.
Any more observations?
Thanks.
Any more observations?
Thanks.
so with tiles that big he will have to use cement based addy so if hes tileing onto gypsum he will need an acrylic primer.
definatlywould have been better with sand and cement, i dnt understand why plasterers dnt warn people bout these things they just get thier money and run
definatlywould have been better with sand and cement, i dnt understand why plasterers dnt warn people bout these things they just get thier money and run
Well what was he plastering over? Perhaps he had to use bonding.
Not ideal as it sucks up moisture, but if it is sealed is there a problem?
There are umpteen jobs been tiled onto gypsum, NHBC approved, architect designed etc etc .
The best way is of course on to rubbed up sand and cement, which has been put onto blocks or bricks, but tiling will continue to be done onto gypsum (and plasterboard) and I've never heard of it giving any problems.
What is the problem with tiling onto bonding? You have two possible points of failure
Bonding to substrate
Tiles to bonding
I've never seen properly applied bonding or gysum come away from a wall - so the problem must be the tiles to the bonding. I'm not a tiler so can someone talk be through this please - cheers!
Not ideal as it sucks up moisture, but if it is sealed is there a problem?
There are umpteen jobs been tiled onto gypsum, NHBC approved, architect designed etc etc .
The best way is of course on to rubbed up sand and cement, which has been put onto blocks or bricks, but tiling will continue to be done onto gypsum (and plasterboard) and I've never heard of it giving any problems.
What is the problem with tiling onto bonding? You have two possible points of failure
Bonding to substrate
Tiles to bonding
I've never seen properly applied bonding or gysum come away from a wall - so the problem must be the tiles to the bonding. I'm not a tiler so can someone talk be through this please - cheers!
same here ive seen it done loadsa times just been told you shouldnt do it by a plasterer round my way a plasterer i respect greatly.
how ever as i said i thought an acrylic primer would allow him to tile onto the bonding no problems, but then again im not a tiler, so i guess final say is up to rich c
how ever as i said i thought an acrylic primer would allow him to tile onto the bonding no problems, but then again im not a tiler, so i guess final say is up to rich c
Unfortunately many “plasterers” are unaware of the properties & limitation of the products they are using when it comes to what will follow on. Some are very proud of their “looks like glass m8” finish or recommend the hapless customer PVA new plaster before painting or tiling, we get examples & consequences of it on here all the time. I started out just plasterign initially & have to admit I didn’t know about the limitations myself until I started to get in to tiling around 5 years ago & then fire surrounds 3 years ago. In fact I even used Bonding to patch on a couple of my first jobs until I was put wise; luckily it was only to patch small holes & they were only small tiles & haven’t fallen off to my knowledge! I also managed to screw up my very own (luckily) fire surround by using Gypsum plaster which subsequently fell off due to the heat; most of you who know me will be aware that's another one I go on about all the time.
Bonding plaster is very porous and will wick moisture away from the adhesive very quickly which can cause curing problems even when primed, it’s also very soft & doesn’t have the strength to allow the adhesive to bond effectively. It didn’t matter much when ceramic was practically all you could get & the largest tiles you could get came in a box the size of a Farmhouse loaf with the name “Crystal” on the side. Tiling is now far more complicated with the increasing popularity of large format tiles & the choice of ceramic, porcelain & a variety of reconstituted & natural stone, some of which weigh a ton.
Here are some extracts from various acredited sources but there are many others too neumerious to mention;
The tile association;
When it is known in advance that tiles are to be fixed to a plastered wall, it is essential that there should be good adhesion between the undercoat and the plaster finish coat. Tiles should only be fixed to the finish coat and must not be fixed directly to a gypsum undercoat."
The Tile Association wishes to acknowledge the assistance provided by British Gypsum and the Federation of Plastering & Drywall Contractors in the drafting of this advice note.
British Gypsum tiling guide;
http://www.british-gypsum.com/pdf/SB07_Tiling_02.pdf
The BG data sheet (top page 3);
http://www.british-gypsum.com/PDF/DS-101-01 Thistle Bonding Coat.pdf
Specifically states “Tiles should not be applied directly to Thistle undercoats with the exception of Thistle Dri-Coat”
The BAL (which I use almost exclusively) data sheets also state stipulate tiling on finish coat only.
Even though those couple of early efforts of mine had no comebacks, I wouldn’t have chanced it if I’d known at the time & certainly wouldn’t risk it now with large format tiles.
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For the OP; I would get it skimmed with Multi & tile over that; your maximum tile weight should be just inside the 20 kg/sqm limit by the time you add on 4 kg/sqm for the cement powder addy, don't attempt to tile with tub ready mix. When using cement addy, you must prime with an acrylic primer to avoid any chance of reaction between the cement in powder adhesive & gypsum. Again, not very widely known is that to avoid problems, you must leave a base + finish plaster coat for 4 weeks before you tile; a skim can be tiled after around 10-14 days. Where time is a factor this is another reason I won’t usually recommend plastering, re-plastering or conventional sand/cement render before tiling, there are other far more suitable products you can use that will allow you to crack on without having to wait around for days, sometimes weeks on end.
Bonding plaster is very porous and will wick moisture away from the adhesive very quickly which can cause curing problems even when primed, it’s also very soft & doesn’t have the strength to allow the adhesive to bond effectively. It didn’t matter much when ceramic was practically all you could get & the largest tiles you could get came in a box the size of a Farmhouse loaf with the name “Crystal” on the side. Tiling is now far more complicated with the increasing popularity of large format tiles & the choice of ceramic, porcelain & a variety of reconstituted & natural stone, some of which weigh a ton.
Here are some extracts from various acredited sources but there are many others too neumerious to mention;
The tile association;
When it is known in advance that tiles are to be fixed to a plastered wall, it is essential that there should be good adhesion between the undercoat and the plaster finish coat. Tiles should only be fixed to the finish coat and must not be fixed directly to a gypsum undercoat."
The Tile Association wishes to acknowledge the assistance provided by British Gypsum and the Federation of Plastering & Drywall Contractors in the drafting of this advice note.
British Gypsum tiling guide;
http://www.british-gypsum.com/pdf/SB07_Tiling_02.pdf
The BG data sheet (top page 3);
http://www.british-gypsum.com/PDF/DS-101-01 Thistle Bonding Coat.pdf
Specifically states “Tiles should not be applied directly to Thistle undercoats with the exception of Thistle Dri-Coat”
The BAL (which I use almost exclusively) data sheets also state stipulate tiling on finish coat only.
Even though those couple of early efforts of mine had no comebacks, I wouldn’t have chanced it if I’d known at the time & certainly wouldn’t risk it now with large format tiles.
---------------00000000000000---------------
For the OP; I would get it skimmed with Multi & tile over that; your maximum tile weight should be just inside the 20 kg/sqm limit by the time you add on 4 kg/sqm for the cement powder addy, don't attempt to tile with tub ready mix. When using cement addy, you must prime with an acrylic primer to avoid any chance of reaction between the cement in powder adhesive & gypsum. Again, not very widely known is that to avoid problems, you must leave a base + finish plaster coat for 4 weeks before you tile; a skim can be tiled after around 10-14 days. Where time is a factor this is another reason I won’t usually recommend plastering, re-plastering or conventional sand/cement render before tiling, there are other far more suitable products you can use that will allow you to crack on without having to wait around for days, sometimes weeks on end.
i have to say although i was plastering for some time before i joined this forum i never knew about all these regulations aswell (like rich) i have learnt ALOT from rich mic and roughcaster and definatly value everything they have taught people and pecially me mabey not in person but i have listened and read everything they have to say.
thanks guys
thanks guys
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