I need to do quite a lot of patch repairs (mostly where I've chased out
elctrical cable runs) on an internal wall which had been previously sand-
cement rendered up to 1m, presumably due to s damp problem at some time in
the past. No sign of damp now, but I'd rather do the repairs properly with
similar sand-cement basecoat to avoid potentially compromising things. One
area is about 2'x3' though. I've got a plasterer booked to skim the whole
room afterwards.

Question - how long should my repairs be left to cure before overskimming?
I've been googling and advice seems conflicted as to whether it should be
left for weeks until it's bone dry, or done within a day so it's
deliberately still damp!

I'm on a rather rigid schedule, in that I have the plasterer booked to
start here on a Wednesday (I doubt he'll be skimming till Thursday though),
and I was hoping to do my stuff the previous Sunday (I get back from
holiday on the Saturday). Will that work? Or do I need to do it tonight
after work, which I *really* don't want to do but is the only other
realistic option, giving a gap of 2.5 weeks?

Thanks

--
David

On 06/10/2014 08:22, Lobster wrote:
I need to do quite a lot of patch repairs (mostly where I've chased out
elctrical cable runs) on an internal wall which had been previously sand-
cement rendered up to 1m, presumably due to s damp problem at some time in
the past. No sign of damp now, but I'd rather do the repairs properly with
similar sand-cement basecoat to avoid potentially compromising things. One
area is about 2'x3' though. I've got a plasterer booked to skim the whole
room afterwards.

Question - how long should my repairs be left to cure before overskimming?
I've been googling and advice seems conflicted as to whether it should be
left for weeks until it's bone dry, or done within a day so it's
deliberately still damp!

I'm on a rather rigid schedule, in that I have the plasterer booked to
start here on a Wednesday (I doubt he'll be skimming till Thursday though),
and I was hoping to do my stuff the previous Sunday (I get back from
holiday on the Saturday). Will that work? Or do I need to do it tonight
after work, which I *really* don't want to do but is the only other
realistic option, giving a gap of 2.5 weeks?

Thanks


In my recent experience patching up an old garden wall, an inch depth of
render will be dry enough to take the next layer in 48 hours. Do it
tonight, albeit in a slap happy fashion. Doesn't have to perfect, but it
needs to be dry by Wednesday :-)

In article ,
Lobster writes:
I need to do quite a lot of patch repairs (mostly where I've chased out
elctrical cable runs) on an internal wall which had been previously sand-
cement rendered up to 1m, presumably due to s damp problem at some time in
the past. No sign of damp now, but I'd rather do the repairs properly with
similar sand-cement basecoat to avoid potentially compromising things. One
area is about 2'x3' though. I've got a plasterer booked to skim the whole
room afterwards.

Question - how long should my repairs be left to cure before overskimming?
I've been googling and advice seems conflicted as to whether it should be
left for weeks until it's bone dry, or done within a day so it's
deliberately still damp!

Either will work, but they work in different ways.
Finish coat can be applied direct in 24-48 hours and will bond into
the cement. After that, the cement will have set too much for a direct
cement bond, and it will need to be done as for a reskim - PVA'ed first,
which ideally wants the cement set a bit more, and the wall drier.

I'm on a rather rigid schedule, in that I have the plasterer booked to
start here on a Wednesday (I doubt he'll be skimming till Thursday though),
and I was hoping to do my stuff the previous Sunday (I get back from
holiday on the Saturday). Will that work? Or do I need to do it tonight
after work, which I *really* don't want to do but is the only other
realistic option, giving a gap of 2.5 weeks?

If you have a plasterer for more than a day, why not get the plasterer to
do it?

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

On 06 Oct 2014, (Andrew Gabriel) grunted:

In article ,
Lobster writes:

Question - how long should my repairs be left to cure before
overskimming? I've been googling and advice seems conflicted as to
whether it should be left for weeks until it's bone dry, or done
within a day so it's deliberately still damp!

Either will work, but they work in different ways.
Finish coat can be applied direct in 24-48 hours and will bond into
the cement. After that, the cement will have set too much for a direct
cement bond, and it will need to be done as for a reskim - PVA'ed
first, which ideally wants the cement set a bit more, and the wall
drier.

Ah OK - makes sense. Does that mean though that I'm Ok doing it just
*outside* that 24-48 hr window (ie, in my case it would probably be 4
days.

If you have a plasterer for more than a day, why not get the plasterer
to do it?

Well yes, the obvious answer! Just that I've already got this guy booked
with a fixed quote (which I already think is pretty high) and don't want
to start renegotiating. Plus I can easily do this bit myself (ie for the
cost of materials); I'm just not sure about the timing.

Thanks
--
David

In article ,
Lobster writes:
On 06 Oct 2014, (Andrew Gabriel) grunted:

In article ,
Lobster writes:

Question - how long should my repairs be left to cure before
overskimming? I've been googling and advice seems conflicted as to
whether it should be left for weeks until it's bone dry, or done
within a day so it's deliberately still damp!

Either will work, but they work in different ways.
Finish coat can be applied direct in 24-48 hours and will bond into
the cement. After that, the cement will have set too much for a direct
cement bond, and it will need to be done as for a reskim - PVA'ed
first, which ideally wants the cement set a bit more, and the wall
drier.

Ah OK - makes sense. Does that mean though that I'm Ok doing it just
*outside* that 24-48 hr window (ie, in my case it would probably be 4
days.

Just reread the OP, and given that it's just patches, the wall is
going to have to be PVA'ed anyway, so you might as well do it ASAP.
It will probably dry faster than if you were rendering a large area
too.

Note that if the sand/cement render is to protect against damp, it
will have had a waterproofer addmix added to the mix. You can buy
combined plasticiser/waterproofer addmix (note that you only use it
sparingly). If you don't use that, you might find it tracks enough
damp though to show the patches afterwards.

If you have a plasterer for more than a day, why not get the plasterer
to do it?

Well yes, the obvious answer! Just that I've already got this guy booked
with a fixed quote (which I already think is pretty high) and don't want
to start renegotiating. Plus I can easily do this bit myself (ie for the
cost of materials); I'm just not sure about the timing.

Thanks

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

On 06/10/14 08:22, Lobster wrote:
Question - how long should my repairs be left to cure before overskimming?
I've been googling and advice seems conflicted as to whether it should be
left for weeks until it's bone dry, or done within a day so it's
deliberately still damp!

perfectly OK to skim damp, but dont DECORATE till its properly dried.

skimming works by setting, paint works by truing, more or less.


--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll