I'm renovating a small bathroom and want to tile onto a block wall
that has been finished with a sand/cement render. The 30 year old
plasterwork that was on has been removed - it more or less fell off.
The wall is out of plumb by about 1.5cm bottom to top, and surface
hollows of about 8mm over 2m. I don't think I'll get a good result
tiling onto it as-is

I was originally planning of getting a plasterer in, but was starting
to think about DIY as the final surface does not need to be perfect -
just good enough to take tiles.

What about using something like Ardex AM 100 "Rapid Hardening One Coat
Tiling Render" (http://www.ardex.co.uk/ardex_am100.asp) which
apparently will apply in 2mm-20mm in one coat. How hard is it for a
novice to get a decent result with this type of thing? The short
working time is a bit of a concern.

Another option would be to dot-and-dab 9.5mm plasterboard - but I will
lose more space this way - but it would be a lot easier.

Niall

In article m,
Niall Smart writes:
I'm renovating a small bathroom and want to tile onto a block wall
that has been finished with a sand/cement render. The 30 year old
plasterwork that was on has been removed - it more or less fell off.
The wall is out of plumb by about 1.5cm bottom to top, and surface
hollows of about 8mm over 2m. I don't think I'll get a good result
tiling onto it as-is

I was originally planning of getting a plasterer in, but was starting
to think about DIY as the final surface does not need to be perfect -
just good enough to take tiles.

Personally, I would put another scratch coat on.
You could either put this on the coat already there if it's well
attached and you can afford the loss of 1.5cm of room, or you could
take it off first, but that could be hard work.

I've posted in some detail how to get a scratch coat vertical, flat,
and true. See:
http://groups.google.co.uk/group/uk....1e3f05f98e8d4f
and substitute sand and cement for plaster. You could use plaster,
although sand and cement would be slightly better for tiling onto.

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

On 27 Sep, 17:22, Niall Smart wrote:
I'm renovating a small bathroom and want to tile onto a block wall
that has been finished with a sand/cement render. The 30 year old
plasterwork that was on has been removed - it more or less fell off.
The wall is out of plumb by about 1.5cm bottom to top, and surface
hollows of about 8mm over 2m. I don't think I'll get a good result
tiling onto it as-is

I was originally planning of getting a plasterer in, but was starting
to think about DIY as the final surface does not need to be perfect -
just good enough to take tiles.

What about using something like Ardex AM 100 "Rapid Hardening One Coat
Tiling Render" (http://www.ardex.co.uk/ardex_am100.asp) which
apparently will apply in 2mm-20mm in one coat. How hard is it for a
novice to get a decent result with this type of thing? The short
working time is a bit of a concern.

Another option would be to dot-and-dab 9.5mm plasterboard - but I will
lose more space this way - but it would be a lot easier.

Niall

I agree with the other post

Use 3:1 sand and cement. Add a glue such as Feb SBR to ensure
adhesion.
it is best for an amateur to use the "screed" method whereby you put
on vertical lines about 4 to 6" wide near each corner and get these
absolutely right first (much easier) and once they have set you can
just fill in between
Plastering is not that difficult if you are reasonably competent DIY
and read up on the techniques.
Chris

On Sep 27, 9:31 pm, (Andrew Gabriel)
wrote:
In article m,
Niall Smart writes:

The wall is out of plumb by about 1.5cm bottom to top, and surface
hollows of about 8mm over 2m. I don't think I'll get a good result
tiling onto it as-is

Personally, I would put another scratch coat on.
You could either put this on the coat already there if it's well
attached and you can afford the loss of 1.5cm of room, or you could
take it off first, but that could be hard work.

I've posted in some detail how to get a scratch coat vertical, flat,
and true. See:http://groups.google.co.uk/group/uk....1e3f05f98e8d4f
and substitute sand and cement for plaster. You could use plaster,
although sand and cement would be slightly better for tiling onto.

Andrew/Chris

Thanks for your replies - very useful, I think I will give it a go
myself and save a few hundred euro. I was wondering how to setup
screeds to make it easier - that plumb dot and plaster screed
technique you describe sounds like it will make it fairly
straightforward. The sand/cement render already on the wall is
fairly solid, so I think I can apply the new coat over it. The nice
thing about the Ardex AM100 was that it can be applied thinly, and
sets quickly - apparently you can tile onto it the same day - wouldn't
I have to leave a regular sand and portland cement render 2-4 weeks?

Niall

Niall

In article om,
Niall Smart writes:
Thanks for your replies - very useful, I think I will give it a go
myself and save a few hundred euro. I was wondering how to setup
screeds to make it easier - that plumb dot and plaster screed
technique you describe sounds like it will make it fairly
straightforward. The sand/cement render already on the wall is
fairly solid, so I think I can apply the new coat over it. The nice
thing about the Ardex AM100 was that it can be applied thinly, and
sets quickly - apparently you can tile onto it the same day - wouldn't
I have to leave a regular sand and portland cement render 2-4 weeks?

Yes you would, but I'm not familiar with the product you mention.
Check if it requires any type of bonding layer on the existing
render. Mortar has a two-stage set. The first happens within 24
hours at which point it won't move anymore, but will break easily
(or at the micro level, you can brush the surface off with your
hand). The second stage takes about 6 weeks to reach its final
strength, and then you won't be able to brush the surface off with
your hand. For tiling on, you don't need the full 6 weeks, but it
needs to have dried. Most tile adhesives require the surface to be
dry, which usually requires waiting some days depending on the
thickness of the coat, weather, etc.

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