Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT

wrote:

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

Bonding probably, since concrete is not particularly high suction. None
of the gypsum plasters are exactly damp resistant though. (having said
that, water should not be coming through concrete anyway)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
John Rumm writes:
wrote:

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

Which direction is the damp going in?

Bonding probably, since concrete is not particularly high suction. None
of the gypsum plasters are exactly damp resistant though. (having said
that, water should not be coming through concrete anyway)

All the gypsom plasters will fail on prolonged damp exposure,
as gypsom itself is soluble (slowly).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

Which direction is the damp going in?

Its heavy transient condensation.

Bonding probably, since concrete is not particularly high suction. None
of the gypsum plasters are exactly damp resistant though. (having said
that, water should not be coming through concrete anyway)

All the gypsom plasters will fail on prolonged damp exposure,
as gypsom itself is soluble (slowly).

I've removed all plaster in the damp zones, and will keep that as
concrete only. The plaster will go on the dry areas.

Thanks both of you... bonding it shall be


NT

wrote in message
...
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

Which direction is the damp going in?

Its heavy transient condensation.

Bonding probably, since concrete is not particularly high suction. None
of the gypsum plasters are exactly damp resistant though. (having said
that, water should not be coming through concrete anyway)

All the gypsom plasters will fail on prolonged damp exposure,
as gypsom itself is soluble (slowly).

I've removed all plaster in the damp zones, and will keep that as
concrete only. The plaster will go on the dry areas.

Thanks both of you... bonding it shall be


NT

May be totally wrong but I thought plaster isn't a preferred base for tiles
and it has (or is recommended ) to be primed? Is there a problem using an
SBR mortar mix?
From http://www.tilersforums.co.uk (cement = cement based adhesive )
A) if it's cement V plaster, you have to prime it, the cement and plaster
don't mix well and bond can become free in the future B) cement based
adhesive are not waterproof, they're water resistant, so they allow water to
pass through them and they don't break down, but the plaster or plasterboard
behind will and can.

PeterK

PeterK wrote:
wrote in message
...
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

Which direction is the damp going in?

Its heavy transient condensation.

Bonding probably, since concrete is not particularly high suction. None
of the gypsum plasters are exactly damp resistant though. (having said
that, water should not be coming through concrete anyway)

All the gypsom plasters will fail on prolonged damp exposure,
as gypsom itself is soluble (slowly).

I've removed all plaster in the damp zones, and will keep that as
concrete only. The plaster will go on the dry areas.

Thanks both of you... bonding it shall be


NT

May be totally wrong but I thought plaster isn't a preferred base for tiles
and it has (or is recommended ) to be primed? Is there a problem using an
SBR mortar mix?

I suppose its an option, not going to handle as well as plaster
though.

From http://www.tilersforums.co.uk (cement = cement based adhesive )
A) if it's cement V plaster, you have to prime it, the cement and plaster
don't mix well and bond can become free in the future B) cement based
adhesive are not waterproof, they're water resistant, so they allow water to
pass through them and they don't break down, but the plaster or plasterboard
behind will and can.

PeterK

Thats what happened. It was all tile cement on plaster, and the area
that got wet failed. But the dry areas were still perfectly sound.

Can SBR be added to plaster? Doesn't sound like its needed though, but
hardly one of my areas of cluefulness.


NT

PeterK wrote:
wrote in message
...
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

Which direction is the damp going in?

Its heavy transient condensation.

Bonding probably, since concrete is not particularly high suction. None
of the gypsum plasters are exactly damp resistant though. (having said
that, water should not be coming through concrete anyway)

All the gypsom plasters will fail on prolonged damp exposure,
as gypsom itself is soluble (slowly).

I've removed all plaster in the damp zones, and will keep that as
concrete only. The plaster will go on the dry areas.

Thanks both of you... bonding it shall be


NT

May be totally wrong but I thought plaster isn't a preferred base for tiles
and it has (or is recommended ) to be primed? Is there a problem using an
SBR mortar mix?

just wouldnt handle well. Some of this has to go on very thinly.


From http://www.tilersforums.co.uk (cement = cement based adhesive )
A) if it's cement V plaster, you have to prime it, the cement and plaster
don't mix well and bond can become free in the future B) cement based
adhesive are not waterproof, they're water resistant, so they allow water to
pass through them and they don't break down, but the plaster or plasterboard
behind will and can.

PeterK

On the damp areas all plaster has been removed, as that's what
happened. I'm just looking to smooth out the dry areas with plaster,
and that worked long term before.


Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes. Is it a terrible idea?
- given that the current plan for those areas is to plaster and tile.


NT

wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.

I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?

Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.

- given that the current plan for those areas is to plaster and tile.

Normally if its a wet service area, they suggest a waterproof adhesive,
and to use a full bed of it - i.e. skim the wall with the glue to a
couple of mm, and then add ribs the top - but not through to the wall.
That way any water that gets through the grout, can't get as far as the
plaster.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.

I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?

Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.

The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.


- given that the current plan for those areas is to plaster and tile.

Normally if its a wet service area, they suggest a waterproof adhesive,
and to use a full bed of it - i.e. skim the wall with the glue to a
couple of mm, and then add ribs the top - but not through to the wall.
That way any water that gets through the grout, can't get as far as the
plaster.

yes, I'll do that where it can get wet. The plaster thought was just
for where it doesnt. I can't think of any good reason to spend many
times as much on waterproof adhesive there.


NT

wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.

The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.

Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 28 Apr, 21:07, wrote:
Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT

Sorry, joined this rather late and am confused as to the purpose of
the tiles and what is meant by heavy transient condensation not to
mention the absence of an answer to the question as to thet direction
of the damp.
Howvever, on the assumption that the tiling is to stop damp going from
the tile side to the concrete (as in a shower or bathroom) my tuppence
happ'ths worth is that I would not go a country mile near any gypsum
plaster and indeed (if it were feasible) would get shot of the
existing gypsum that is allegedly sound. If this is not practicable
on the grounds of qantum and you are, indeed, just patching up an
existing wall with tiles that have failed I would
a) ensure that the removal of apparently unsound plaster and tiles is
extended at least one tile further than the "failure"
b) remove all gypsum from the concrete where you are patching in and
key the concrete
c) apply a sand cement render to it with SBR (or if you can afford it
Ardex render)
d) tile and then regrout well into the old tiled area if not the lot

I may well have misunderstood so forgive me if I have the wrong end of
the stick but the basics are water and gypsum are not natural
bedfellows

Chris

In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.

The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.

Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.

Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

coughed up some electrons that declared:

On 28 Apr, 21:07, wrote:
Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT

Sorry, joined this rather late and am confused as to the purpose of
the tiles and what is meant by heavy transient condensation not to
mention the absence of an answer to the question as to thet direction
of the damp.
Howvever, on the assumption that the tiling is to stop damp going from
the tile side to the concrete (as in a shower or bathroom) my tuppence
happ'ths worth is that I would not go a country mile near any gypsum
plaster and indeed (if it were feasible) would get shot of the
existing gypsum that is allegedly sound. If this is not practicable
on the grounds of qantum and you are, indeed, just patching up an
existing wall with tiles that have failed I would
a) ensure that the removal of apparently unsound plaster and tiles is
extended at least one tile further than the "failure"
b) remove all gypsum from the concrete where you are patching in and
key the concrete
c) apply a sand cement render to it with SBR (or if you can afford it
Ardex render)
d) tile and then regrout well into the old tiled area if not the lot

I may well have misunderstood so forgive me if I have the wrong end of
the stick but the basics are water and gypsum are not natural
bedfellows

Chris

Is there anything that can be applied to sound gypsum to make it more water
resistant?

Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.

The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.

Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.

Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.

Can't I just mix it thick to avoid slip?


NT

wrote:
On 28 Apr, 21:07, wrote:
Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT

Sorry, joined this rather late and am confused as to the purpose of
the tiles and what is meant by heavy transient condensation not to
mention the absence of an answer to the question as to thet direction
of the damp.
Howvever, on the assumption that the tiling is to stop damp going from
the tile side to the concrete (as in a shower or bathroom) my tuppence
happ'ths worth is that I would not go a country mile near any gypsum
plaster and indeed (if it were feasible) would get shot of the
existing gypsum that is allegedly sound. If this is not practicable
on the grounds of qantum and you are, indeed, just patching up an
existing wall with tiles that have failed I would
a) ensure that the removal of apparently unsound plaster and tiles is
extended at least one tile further than the "failure"
b) remove all gypsum from the concrete where you are patching in and
key the concrete
c) apply a sand cement render to it with SBR (or if you can afford it
Ardex render)
d) tile and then regrout well into the old tiled area if not the lot

I may well have misunderstood so forgive me if I have the wrong end of
the stick but the basics are water and gypsum are not natural
bedfellows

Chris


OK, bit more info. All the walls were gypsum plastered, and held out
fine for decades. But eventually damp areas failed, the rest stayed
strongly attached. So duplicating that situation in the dry areas I
wouldnt expect to be a problem. The damp areas have had all traces of
gypsum eliminated - I had hoped to eliminate all gypsum everywhere,
but its just too big a job.


NT

wrote:
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.

The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.

Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.

Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.

Can't I just mix it thick to avoid slip?


NT

or is there a suitable additive? I expect not, but...


NT

wrote:
wrote:
On 28 Apr, 21:07, wrote:
Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT
Sorry, joined this rather late and am confused as to the purpose of
the tiles and what is meant by heavy transient condensation not to
mention the absence of an answer to the question as to thet direction
of the damp.
Howvever, on the assumption that the tiling is to stop damp going from
the tile side to the concrete (as in a shower or bathroom) my tuppence
happ'ths worth is that I would not go a country mile near any gypsum
plaster and indeed (if it were feasible) would get shot of the
existing gypsum that is allegedly sound. If this is not practicable
on the grounds of qantum and you are, indeed, just patching up an
existing wall with tiles that have failed I would
a) ensure that the removal of apparently unsound plaster and tiles is
extended at least one tile further than the "failure"
b) remove all gypsum from the concrete where you are patching in and
key the concrete
c) apply a sand cement render to it with SBR (or if you can afford it
Ardex render)
d) tile and then regrout well into the old tiled area if not the lot

I may well have misunderstood so forgive me if I have the wrong end of
the stick but the basics are water and gypsum are not natural
bedfellows

Chris


OK, bit more info. All the walls were gypsum plastered, and held out
fine for decades. But eventually damp areas failed, the rest stayed
strongly attached. So duplicating that situation in the dry areas I
wouldnt expect to be a problem. The damp areas have had all traces of
gypsum eliminated - I had hoped to eliminate all gypsum everywhere,
but its just too big a job.

Too right, since its in every bag of plaster or cement you buy..and in
tile cement too ptrobably.



NT

wrote:
wrote:
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.
The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.
Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.
Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.
Can't I just mix it thick to avoid slip?


NT

or is there a suitable additive? I expect not, but...


NT

You're beginning to sound like a bit of a fruitcake.

Stuart Noble wrote:
wrote:
wrote:
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.
The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.
Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.
Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.
Can't I just mix it thick to avoid slip?


NT

or is there a suitable additive? I expect not, but...


NT

You're beginning to sound like a bit of a fruitcake.

Structural elements of buildings have been constructed using just
gypsum and tiles, but for asking if gypsum can stick tiles to a wall
I'm a fruitcake? Uhuh, ok.


NT

wrote:
Stuart Noble wrote:
wrote:
wrote:
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.
The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.
Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.
Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.
Can't I just mix it thick to avoid slip?


NT
or is there a suitable additive? I expect not, but...


NT
You're beginning to sound like a bit of a fruitcake.

Structural elements of buildings have been constructed using just
gypsum and tiles, but for asking if gypsum can stick tiles to a wall
I'm a fruitcake? Uhuh, ok.


NT

If you could get away with plaster, tilers would be delighted I'm sure.
Just spend £20 on a bag of tile adhesive and save yourself the worry

Stuart Noble wrote:
wrote:
Stuart Noble wrote:
wrote:
wrote:
Andrew Gabriel wrote:
In article ,
John Rumm writes:
wrote:
John Rumm wrote:
wrote:

Wacky question now... in dry areas can wall tiles be adhered on using
plaster? I'm fairly positive the answer's yes.
I am sure you could get them to stick to bonding - it sticks to most
things.

Is it a terrible idea?
Yes. It would be a right bugger to plaster, and get it flat enough while
still wet enough to stick a tile to.
The cunning plan was to patch plaster it flat, scratch it, and once
dry to tile as usual, but using plaster. I'm sure the answer's yes, it
works.
Yup, that would probably work. Be interesting to know how well, since
there is a big difference in price.

The limitation may be the amount of slip you get compared to a good
adhesive.
Plaster rapidly changes consistency. As normally used, there would
be too much slip -- it only just holds itself, and wouldn't hold a
tile too. But it quickly sets, probably past the point where you
can get suction to a tile-back. So whilst it might work, you probably
only have a few minutes where it's capable of taking a tile, probably
around 15 minutes after mixing.

Tile cement OTOH remains usable for at least half an hour, so you can
get a reasonable number fitted and area covered with each mixing.
Can't I just mix it thick to avoid slip?


NT
or is there a suitable additive? I expect not, but...


NT
You're beginning to sound like a bit of a fruitcake.

Structural elements of buildings have been constructed using just
gypsum and tiles, but for asking if gypsum can stick tiles to a wall
I'm a fruitcake? Uhuh, ok.


NT

If you could get away with plaster, tilers would be delighted I'm sure.
Just spend �20 on a bag of tile adhesive and save yourself the worry

I've spent a lot more than that. I guess the answer is obvious, take a
bit of sheet material and tile it with bonding plaster, see if it
works.


NT

On Sat, 02 May 2009 07:09:21 +0100, The Natural Philosopher
wrote:

wrote:
wrote:
On 28 Apr, 21:07, wrote:
Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT
Sorry, joined this rather late and am confused as to the purpose of
the tiles and what is meant by heavy transient condensation not to
mention the absence of an answer to the question as to thet direction
of the damp.
Howvever, on the assumption that the tiling is to stop damp going from
the tile side to the concrete (as in a shower or bathroom) my tuppence
happ'ths worth is that I would not go a country mile near any gypsum
plaster and indeed (if it were feasible) would get shot of the
existing gypsum that is allegedly sound. If this is not practicable
on the grounds of qantum and you are, indeed, just patching up an
existing wall with tiles that have failed I would
a) ensure that the removal of apparently unsound plaster and tiles is
extended at least one tile further than the "failure"
b) remove all gypsum from the concrete where you are patching in and
key the concrete
c) apply a sand cement render to it with SBR (or if you can afford it
Ardex render)
d) tile and then regrout well into the old tiled area if not the lot

I may well have misunderstood so forgive me if I have the wrong end of
the stick but the basics are water and gypsum are not natural
bedfellows

Chris


OK, bit more info. All the walls were gypsum plastered, and held out
fine for decades. But eventually damp areas failed, the rest stayed
strongly attached. So duplicating that situation in the dry areas I
wouldnt expect to be a problem. The damp areas have had all traces of
gypsum eliminated - I had hoped to eliminate all gypsum everywhere,
but its just too big a job.

Too right, since its in every bag of plaster or cement you buy..and in
tile cement too ptrobably.



NT
Depends on the gypsum plaster. Carlite was notorious in being
hygroscopic and should not be used anywhere near any damp. Thistle on
the other hand...

Maris wrote:
On Sat, 02 May 2009 07:09:21 +0100, The Natural Philosopher
wrote:

wrote:
wrote:
On 28 Apr, 21:07, wrote:
Hi

which plaster do I need to level a wall before tiling? IOW I'm not
after a fine finish, but the more strength and damp resistance the
better. The wall's concrete.

thanks, NT
Sorry, joined this rather late and am confused as to the purpose of
the tiles and what is meant by heavy transient condensation not to
mention the absence of an answer to the question as to thet direction
of the damp.
Howvever, on the assumption that the tiling is to stop damp going from
the tile side to the concrete (as in a shower or bathroom) my tuppence
happ'ths worth is that I would not go a country mile near any gypsum
plaster and indeed (if it were feasible) would get shot of the
existing gypsum that is allegedly sound. If this is not practicable
on the grounds of qantum and you are, indeed, just patching up an
existing wall with tiles that have failed I would
a) ensure that the removal of apparently unsound plaster and tiles is
extended at least one tile further than the "failure"
b) remove all gypsum from the concrete where you are patching in and
key the concrete
c) apply a sand cement render to it with SBR (or if you can afford it
Ardex render)
d) tile and then regrout well into the old tiled area if not the lot

I may well have misunderstood so forgive me if I have the wrong end of
the stick but the basics are water and gypsum are not natural
bedfellows

Chris


OK, bit more info. All the walls were gypsum plastered, and held out
fine for decades. But eventually damp areas failed, the rest stayed
strongly attached. So duplicating that situation in the dry areas I
wouldnt expect to be a problem. The damp areas have had all traces of
gypsum eliminated - I had hoped to eliminate all gypsum everywhere,
but its just too big a job.

Too right, since its in every bag of plaster or cement you buy..and in
tile cement too ptrobably.



NT
Depends on the gypsum plaster. Carlite was notorious in being
hygroscopic and should not be used anywhere near any damp. Thistle on
the other hand...

I've not been out to get it yet, but Thistle is what I had in my
sights


cheers, NT