Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

TIA

On 24 July, 21:57, Fred wrote:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

TIA

just buy a moulding to extend the winda frame?

Cheers
Jim K

On Jul 24, 9:57*pm, Fred wrote:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

TIA

6mm plasterboard does exist, although probably a special order so may
not be a solution. It's fibreglass reinforced I think, and designed
for boarding curves.

I would have used an insulated plasterboard - something like the Knauf
Thermal Laminate Plus at 27mm total thickness.

Alternatively, you could cover the insulation with metal lath, eg
http://www.diy.com/diy/jsp/bq/nav.js...h=lath&x=0&y=0
and then plaster. Not sure what thickness you'd end up with, but
probably less than plasterboard.

A

On Sun, 25 Jul 2010 01:05:42 -0700 (PDT), andrew
wrote:

I would have used an insulated plasterboard - something like the Knauf
Thermal Laminate Plus at 27mm total thickness.

That would have been ideal, what a shame I didn't know about it when I
began!

I'll have to phone around to see who stocks 6mm plasterboard tomorrow.
I think only Lafarge make it.

Thanks.

In article , Fred
writes
On Sun, 25 Jul 2010 01:05:42 -0700 (PDT), andrew
wrote:

I would have used an insulated plasterboard - something like the Knauf
Thermal Laminate Plus at 27mm total thickness.

That would have been ideal, what a shame I didn't know about it when I
began!

I'll have to phone around to see who stocks 6mm plasterboard tomorrow.
I think only Lafarge make it.

It hardly seems worth the effort to save 3mm.

You could face the insulation with 3mm ply and finish it as you had
planned for the PB, either paint or paper.

If you decide to paint it you can leave it looking like wood or fill the
grain with board filler or even polyfilla to leave a plaster smooth
finish that can be primed then emulsioned. In the latter case it's not a
skim coat you are applying, it is just enough to fill the grain so is
nominally zero thickness.

You could put thinner insulation in the reveals, it would make little
difference to the overall heat loss as the area involved is small but
could help avoid local condensation. To avoid buying a full sheet of
thinner stuff I have sawn small lengths of PIR foam in half depth wise
but you wouldn't want to do a lot of it. You could use a layer or 2 of
polystyrene tiles instead of PIR with some loss in efficacy but I don't
think that's a big issue.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

On Jul 24, 9:57*pm, Fred wrote:
I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal).

AFAIK industry practice is...
- 12mm Celotex with 9mm PB over the top
- 20mm Polystyrene + PVA + plaster skim

You can use Marmox 6mm 10mm 12.5mm 20mm...
- Cement & glass-fibre mesh on extruded polystyrene + plaster skim

Marmox is actually better than expanded polystyrene re waterproof.

Jim K wrote:
On 24 July, 21:57, Fred wrote:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't
expect there is a plasterboard any thinner because it would be too
fragile to transport but can you plaster on top of say hardboard?
Does it need any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

TIA

just buy a moulding to extend the winda frame?


How is he going to do that? - he'd have to replace the glass units.


--
Phil L
RSRL Tipster Of The Year 2008

Fred wrote:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

TIA

Have you took off the old plaster down to bare brick? - you'll gain up to
25mm there.

--
Phil L
RSRL Tipster Of The Year 2008

In article ,
Fred writes:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

Yes.

You might want a scratch coat (use bonding coat plaster)
as finish coat by itself might be a bit fragile on celotex.

You can plaster a sheet of glass if you PVA it first.

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

Andrew Gabriel wrote:
In article ,
Fred writes:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

Yes.

You might want a scratch coat (use bonding coat plaster)
as finish coat by itself might be a bit fragile on celotex.

You can plaster a sheet of glass if you PVA it first.

you could use rendering mesh and bonding plaster for a really thin finish.

In article ,
The Natural Philosopher writes:
Andrew Gabriel wrote:
In article ,
Fred writes:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

Yes.

You might want a scratch coat (use bonding coat plaster)
as finish coat by itself might be a bit fragile on celotex.

You can plaster a sheet of glass if you PVA it first.

you could use rendering mesh and bonding plaster for a really thin finish.

It's called metal lath.
You would want stainless steel, not galvanised, near a window,
and stainless steel fixings. It's a complete ******* to handle.
Comes in 8'x3' sheets, and every edge is like a giant razor blade,
and even the surface is like a giant cheese grater. I used some a
few months ago, and in spite of being careful, I still managed
to cut myself several times. You don't even know you've done it,
as mostly it's completely painless at the time. Then you notice
things are getting blood on them, and you've got blood on your
hands, and you start trying to work out where it's coming from.
It's probably a bit thick for what you want, and it doesn't
necessarily lay very flat against the surface, so I'm not sure
you'd achieve significantly less than 9mm with it.

Another option I have used for a thin layer is fine welded mesh.
That came from Wickes, but is galvanised rather than S/S. I don't
recall if they or anyone else does a S/S version. It is much
easier to handle.

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

On Sun, 25 Jul 2010 16:21:09 +0100, "Phil L"
wrote:

Have you took off the old plaster down to bare brick?

Yes.

On Mon, 26 Jul 2010 14:39:34 +0000 (UTC),
(Andrew Gabriel) wrote:

It's called metal lath.
You would want stainless steel, not galvanised, near a window,
and stainless steel fixings. It's a complete ******* to handle.
Comes in 8'x3' sheets, and every edge is like a giant razor blade,
and even the surface is like a giant cheese grater. I used some a
few months ago, and in spite of being careful, I still managed
to cut myself several times. You don't even know you've done it,
as mostly it's completely painless at the time. Then you notice
things are getting blood on them, and you've got blood on your
hands, and you start trying to work out where it's coming from.
It's probably a bit thick for what you want, and it doesn't
necessarily lay very flat against the surface, so I'm not sure
you'd achieve significantly less than 9mm with it.

I thought that if I used 6mm plasterbaord rather than 12.5mm, that a
saving of 6mm would be quite significant. I could only find 6mm
plasterboard on lafarge's web site, not on British Gypsum or Knauff's.
When I called Lafarge's freephone number to find a stockist, the lady
told me they didn't make 6mm plasterboard. I tried to explain that
they made a 6mm contourboard and that it was on their website but in
the end I hung up in frustration because she wouldn't believe me!

I phoned around a lot of builder's merchants and no-one had any and
no-one was interested in finding any. I did eventually find someone
with just four sheets in stock but they wanted 19gbp plus VAT. So I
decided that the 3mm difference between 6mm and 9mm plasterboard would
not be noticeable and bought 9.5mm PB for a fifth of that cost and
used that instead.

I had thought a lath may have allowed me to go thinner but like you
said, the idea of cutting it and it cutting me put me off and being
new to plaster, I wasn't use how easy it would be for a novice to
skim?

BTW I have bought a couple of angle beads to use. Do you hold these in
place with a couple of plasterboard screws, glue (no more tails type
of thing), or just push them into the wet plaster?

Thanks.

In article ,
Fred writes:

BTW I have bought a couple of angle beads to use. Do you hold these in
place with a couple of plasterboard screws, glue (no more tails type
of thing), or just push them into the wet plaster?

Plaster board beads - I just run some plaster up the back, and then
push on to the plasterboard, and plaster should ooze through the slots.
If the beads or the edge are not flat, you might need a screw or nail.
Again, should really use non-rusting ones, as if it ever gets damp,
you can get rust marks coming through the paintwork.

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

On Thu, 29 Jul 2010 15:15:54 +0000 (UTC),
(Andrew Gabriel) wrote:

Plaster board beads - I just run some plaster up the back, and then
push on to the plasterboard,

That's what I did, thanks. Just wanted to make sure I hadn't done it
wrong

Thanks again.

replying to Fred, Mario Toro Paz wrote:
you could use 6mm mdf

--
for full context, visit http://www.homeownershub.com/uk-diy/...te-645810-.htm

On Friday, 9 September 2016 12:44:04 UTC+1, Mario Toro Paz wrote:
replying to Fred, Mario Toro Paz wrote:
you could use 6mm mdf

that'll be useful, 6 years later.

try this
http://wiki.diyfaq.org.uk/index.php/Home_owners_hub


NT

wrote:

Mario Toro Paz wrote:

you could use 6mm mdf

try this
http://wiki.diyfaq.org.uk/index.php/Home_owners_hub

Home owners hub seems to filter out all messages mentioning its name, so
Mario is unlikely to see your helpful link

On 09/09/2016 14:33, Andy Burns wrote:
wrote:

Mario Toro Paz wrote:

you could use 6mm mdf

try this
http://wiki.diyfaq.org.uk/index.php/xxxxxxxxxxxx

Hxxxx oxxxxx hub seems to filter out all messages mentioning its name, so
Mario is unlikely to see your helpful link

That's a shame. I've even tried to create an account there, but the site
won't allow for a legal "_" in a name!

Fredxxx wrote:

Andy Burns wrote:

wrote:

http://wiki.diyfaq.org.uk/index.php/xxxxxxxxxxxx

Hxxxx oxxxxx hub seems to filter out all messages mentioning its name, so
Mario is unlikely to see your helpful link

That's a shame.

Actually it seems to be playing catch-up, NT's and my message have shown
there now, yours not yet, I guess an underscore or a space is enough to
fool their filter.

On 09/09/16 12:44, Mario Toro Paz wrote:
replying to Fred, Mario Toro Paz wrote:
you could use 6mm mdf

you could expanded metal mesh, or lath...


--
Canada is all right really, though not for the whole weekend.

"Saki"

On Saturday, 24 July 2010 21:57:57 UTC+1, Fred wrote:
Hi,

I've been retrofitting celotex to a room. It's gone well except for
one slight problem: the window reveal (I put 25mm celotex inside the
reveal). I'm worried that even if I use 9.5mm, rather than 12.5mm,
plasterboard on top of the celotex that it might overlap too much of
the side of the window frame. I'm not sure how much of a problem this
will be: any overlap will only be cosmetic, it's not going to block
the window or prevent it opening or anything that drastic but will it
look "odd"?

What would you do? Use 9.5mm PB? If there is an overlap (i) it will
probably be hidden by blinds/curtains/whatever SWMBO puts there or
(ii) if we do see it, we may grow used to it.

Alternatively is there something thinner than 9.5mm PB? I don't expect
there is a plasterboard any thinner because it would be too fragile to
transport but can you plaster on top of say hardboard? Does it need
any treatment first (primer? undercoat?) or just PVA?

Or can you PVA celotex and plaster directly on to that?

TIA

Or, I have removed the foil and used plaster and PVA to put a thin skim of plaster direct onto the foam. No problems so far, five years ago.

In article ,
harry writes:
On Saturday, 24 July 2010 21:57:57 UTC+1, Fred wrote:
Or can you PVA celotex and plaster directly on to that?

Yes, you can even PVA glass and plaster onto that.

Or, I have removed the foil and used plaster and PVA to put a thin skim of plaster direct onto the foam. No problems so far, five years ago.

It is also manufactured without foil on one or both sides,
although finding a reseller might be a challenge.

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