Fixing celotex or similar to the ceiling
Pete Verdon
bathroom ceilings. The main job was the kitchen, which was damaged by a
water leak, but while he's here I thought he might as well skim over the
ugly old artex in the new bathroom.
It's occurred to me that the bathroom ceiling is really in need of some
more insulation. Unfortunately the odd shape of the roof makes it very
difficult to get at the loft above it. So I thought I might fix some
insulating boards to it before the plasterer visits, and get him to skim
onto those instead. This will also cover an ugly gap that exists at the
top of the tiles.
Any comments on this plan? Screw or glue?
Cheers,
Pete
Tim W
wibbled on Wednesday 18 November 2009 00:13
You could consider Marmox or equivalent - those are a layer of foam faced on
both sides with glass mesh and cement. They can be glued or screwed up and
available in a range of thicknesses. Not as efficient as celotex type
materials but totally vapour proof and according to Mamrox you can apply
skim plaster directly to them (tape joints with scrim as per plasterboard.
I'd fill the joints with silicone first (as I did on a damp floor when
using Marmox under wood) to complete the vapour barrier).
Very light and easy to cut - score n snap as PB, though that stuff will
destroy one stanley blade every few sheets.
--
Tim Watts
This space intentionally left blank...
Pete Verdon
> You could consider Marmox or equivalent
Hmm, I actually have a few sheets of 6mm Marmox in the shed, left over
from the main bathroom build. Not sure that's enough insulation though.
Pete
Tim W
wibbled on Wednesday 18 November 2009 01:09
I was thinking more like 20 or 30mm?
Are you actively trying to stop heat loss or just reduce the cold surface a
bit to lessen condensation?
Pete Verdon
> Pete Verdon <ne...@verdonet.organisation.unitedkingdom.invalid>
>>> You could consider Marmox or equivalent
>> Hmm, I actually have a few sheets of 6mm Marmox in the shed, left over
>> from the main bathroom build. Not sure that's enough insulation though.
> I was thinking more like 20 or 30mm?
Yep. In fact I might go even thicker just in order to cover up the gap
at the top of the tiles. (At one time there was a plan for a false
ceiling on battens, so the tiler didn't bother filling the last inch or
two at the top.) The alternative is some thin coving.
> Are you actively trying to stop heat loss or just reduce the cold surface a
> bit to lessen condensation?
The latter.
Pete
JimK
<n...@verdonet.organisation.unitedkingdom.invalid> wrote:
> Tim W wrote:
get some extruded polystyrene sheets (B&Q apparently do some in packs)
stick em to the celing and then screw you rmarmox underneath so that
plasterer can skim? best of both worlds?
JimK
Andrew Gabriel
Even 25mm Cellotex will achieve that.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Pete Verdon
> Pete Verdon <ne...@verdonet.organisation.unitedkingdom.invalid> writes:
>> Tim W wrote:
>>> Are you actively trying to stop heat loss or just reduce the cold surface a
>>> bit to lessen condensation?
>> The latter.
> Even 25mm Cellotex will achieve that.
That's good to know.
I've never actually handled Celotex before. I had been kind of assuming
I'd stick something up and let the plasterer do his thing, but it's
dawned on me that plaster probably won't stick to plain Celotex, will it?
Pete
John Rumm
You could use a pir foam board and plaster board below. Use long screws
through both layers.
--
Cheers,
John.
/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
NT
<n...@verdonet.organisation.unitedkingdom.invalid> wrote:
> Andrew Gabriel wrote:
Sounds like you've got enough room there to use cheap polystyrene then
a layer of plasterboard
NT
Pete Verdon
> Sounds like you've got enough room there to use cheap polystyrene then
> a layer of plasterboard
The more thickness the better, within reason. The ceiling is unusually
high for a modern house, so no worries about lowering it.
Is polystyrene in the ceiling OK from a fire point of view?
Pete
Tony Bryer
> The more thickness the better, within reason. The ceiling is unusually
> high for a modern house, so no worries about lowering it.
>
> Is polystyrene in the ceiling OK from a fire point of view?
IIRC the really bad thing about polystyrene tiles beloved of 1960s home
'improvers' was that in the event of a fire, the fire spread across them
and burning droplets then spread the fire. Above a ceiling I would have
expected it to have melted long before the plasterboard was penetrated
and if you reach that stage you've got serious problems.
--
Tony Bryer, Greentram: 'Software to build on' Melbourne, Australia
www.superbeam.co.uk www.superbeam.com www.greentram.com
Roger Chapman
> Pete Verdon wrote:
>> I have a plasterer coming round this weekend to do my kitchen and
>> bathroom ceilings. The main job was the kitchen, which was damaged by
>> a water leak, but while he's here I thought he might as well skim over
>> the ugly old artex in the new bathroom.
>>
>> It's occurred to me that the bathroom ceiling is really in need of
>> some more insulation. Unfortunately the odd shape of the roof makes it
>> very difficult to get at the loft above it. So I thought I might fix
>> some insulating boards to it before the plasterer visits, and get him
>> to skim onto those instead. This will also cover an ugly gap that
>> exists at the top of the tiles.
>>
>> Any comments on this plan? Screw or glue?
>
> You could use a pir foam board and plaster board below. Use long screws
> through both layers.
I thought you could get plaster board faced PIR. Would that be more
expensive, or less expensive than getting two separate layers? Fitting a
combined sheet should surely be easier.
Tim W
wibbled on Wednesday 18 November 2009 23:52
No it won't It's (usually) faced in shiney foil.
30+mm Marmox will probably achieve what you want, though not strictly
equivalent to 25mm celotex, but we're not working with critical numbers
here.
If using celotex (or any equivalent product) then you'll need to screw it to
the ceiling timbers with big washers (they make washers for this purpose).
At this point you'll need to cover it with something that takes plaster.
Your choices are now plasterboard (moisture resistant - pink - would be a
good idea), or Marmox or something else with a suitable surface. This would
be screwed through the celotex into the same timbers.
Cheers
Tim
Tim W
wibbled on Thursday 19 November 2009 00:26
> On Thu, 19 Nov 2009 00:17:23 +0000 Pete Verdon wrote :
>> The more thickness the better, within reason. The ceiling is unusually
>> high for a modern house, so no worries about lowering it.
>>
>> Is polystyrene in the ceiling OK from a fire point of view?
>
> IIRC the really bad thing about polystyrene tiles beloved of 1960s home
> 'improvers' was that in the event of a fire, the fire spread across them
> and burning droplets then spread the fire. Above a ceiling I would have
> expected it to have melted long before the plasterboard was penetrated
> and if you reach that stage you've got serious problems.
>
The same might be true of Marmox. Celotex (PIR foams in general) does have
the advantage it doesn't do this.
JimK
> I thought you could get plaster board faced PIR. Would that be more
> expensive, or less expensive than getting two separate layers? Fitting a
> combined sheet should surely be easier.
yup abt £18+vat / 8' X4' sheet for small quantities recently...
Bloody heavy though - 2 man job for any ceiling tho - quick if awkward
JimK
Bruce
There is one Celotex product (PL3000) that has a sheet of Celotex
insulation material bonded to a sheet of plasterboard.
Thickness starts at 37mm (25mm Celotex + 12mm plasterboard) and goes
up from there. The plasterboard has a taper edge.
http://www.celotex.co.uk/Products/Celotex-Products/Celotex-PL3000
Unfortunately, you now have to register with your name, address and
telephone number to obtain the data sheet.
Andrew Gabriel
Bruce <docne...@gmail.com> writes:
>
> There is one Celotex product (PL3000) that has a sheet of Celotex
> insulation material bonded to a sheet of plasterboard.
>
> Thickness starts at 37mm (25mm Celotex + 12mm plasterboard) and goes
> up from there. The plasterboard has a taper edge.
>
> http://www.celotex.co.uk/Products/Celotex-Products/Celotex-PL3000
>
> Unfortunately, you now have to register with your name, address and
> telephone number to obtain the data sheet.
Yep - I stopped planning on using their products at that point.
Andrew Gabriel
PIR foams natively are very flammable. The ones used in building
insulation have varying degrees of fire retardants added (varying
from nothing, so be careful). In any case, even when there's
enough retardant to prevent spread of fire, they still burn in
a fire, releasing toxic gasses.
geraldthehamster
<n...@verdonet.organisation.unitedkingdom.invalid> wrote:
> > Are you actively trying to stop heat loss or just reduce the cold surface a
> > bit to lessen condensation?
>
> The latter.
>
> Pete
I would locate the joists, first attach 25mm foiled Celotex or
Kingspan with plasterboard screws, then screw 9mm plasterboard over
that, through to the joists.
IME, Kingspan foiled board is covered with a strong reinforced foil,
and you could screw straight to the ceiling and the heads won't pull
through. Celotex has a crappy thin foil so you'd need to use bits of
card or similar as washers, to hold it up while you fix the
plasterboard.
Or you can get insulation-backed plasterboard to do it in one.
All are semi-rigid materials in large sheets, that would be quick and
easy to cut and fix, preferably with an assistant to help hold it up
while you screw. So to speak. Don't forget that you have a head to
hold things up with, as well as two hands ;-)
Cheers
Richard
fred
>insulation material bonded to a sheet of plasterboard.
>
>Thickness starts at 37mm (25mm Celotex + 12mm plasterboard) and goes
>up from there. The plasterboard has a taper edge.
>
>http://www.celotex.co.uk/Products/Celotex-Products/Celotex-PL3000
>
was only available (from other mfrs) with less efficient insulation
while thicker ones used polycynodoodah, the exact opposite of what was
required.
>Unfortunately, you now have to register with your name, address and
>telephone number to obtain the data sheet.
>
Well, you have o register with _a_ name, _an_ address and _a_ telephone
number to obtain a data sheet ;-)
I agree with AG's position on this being nn unnecessary PITA but I will
still buy Celotex seconds if they available when Kingspan ones are not
or more expensive.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs
fred
<254ac1e8-0275-4695...@s31g2000yqs.googlegroups.com>,
JimK <jk98...@googlemail.com> writes
>On 19 Nov, 07:37, Roger Chapman <ro...@nospam.zetnet.co.uk> wrote:
>
>> I thought you could get plaster board faced PIR. Would that be more
>> expensive, or less expensive than getting two separate layers? Fitting a
>> combined sheet should surely be easier.
>
>yup abt �18+vat / 8' X4' sheet for small quantities recently...
>
another insulation? Also was it a local source or a national?
Bruce
>In article <6e1ag51hlk2ems4h9...@4ax.com>, Bruce
><docne...@gmail.com> writes
>>There is one Celotex product (PL3000) that has a sheet of Celotex
>>insulation material bonded to a sheet of plasterboard.
>>Thickness starts at 37mm (25mm Celotex + 12mm plasterboard) and goes
>>up from there. The plasterboard has a taper edge.
>>http://www.celotex.co.uk/Products/Celotex-Products/Celotex-PL3000
>>
>That's good to know, when I was looking in the past, the thinner stuff
>was only available (from other mfrs) with less efficient insulation
>while thicker ones used polycynodoodah, the exact opposite of what was
>required.
I'm looking for something thinner, to give a total thickness not
greater than 25mm. I was planning to use 12mm Celotex and
plasterboard, but none of the local merchants stock that thickness and
a special order would involve a whole pallet. It's for a tiny
cloakroom, so I only need one sheet. :-(
>>Unfortunately, you now have to register with your name, address and
>>telephone number to obtain the data sheet.
>>
>Well, you have o register with _a_ name, _an_ address and _a_ telephone
>number to obtain a data sheet ;-)
That's true. I wonder how many people have signed in as M Mouse?
>I agree with AG's position on this being nn unnecessary PITA but I will
>still buy Celotex seconds if they available when Kingspan ones are not
>or more expensive.
It seems a little silly to cut one's self off from a good supplier
just because of the need to register with the supplier's web site.
I agree with the principle, but does cutting off one's nose really
make sense ... ?
js.b1
- Jewsons 50+12.5mm PIR+PB is something like £70/sheet inc VAT.
- Gyproc Thermaline 35mm XPS+PB is about £37/sheet inc VAT.
Marmox is very expensive - 50mm is £17.56/sheet inc VAT and delivery,
min order 5 sheets - but a sheet is just 1200x600mm compared to
2400x1200mm for the previous.
The good thing about Marmox is the waterproof cementitious coating +
waterproof extruded polystyrene + waterproof cementitious coating.
That means it can "catchup" with PIR+PB performance per unit thickness
because you can glue it straight to damp solid brick walls and just
skim it - rather than Baton thickness on top of PIR+PB thickness. For
example 50mm Marmox becomes about 55mm bonded to the wall & skimmed
with R = 1.53, whereas 25mm batons + 25mm PIR + 12.5mm PB (37.5mm K17)
becomes 62.5mm for R = 1.15. You have to go to 25mm batons + 40mm PIR
+ 12.5mm PB (52.5mm K17) which becomes 82.5mm to get R = 1.80. With
batons there is the risk of interstitial condensation with solid
double brick if the dew point happens to migrate out of the wall into
that void.
For a ceiling, I would go with whatever the local building merchant
has and screw thro the PB and the PIR into the joists.
JimK
> The problem with PB backed insulation is the cost & availability.
> - Jewsons 50+12.5mm PIR+PB is something like £70/sheet inc VAT.
> - Gyproc Thermaline 35mm XPS+PB is about £37/sheet inc VAT.
Jewsons? £70 ????? presume you don't have an account then
Try a local insulation specialist - 25mm foiled PIR + 12.5mm taper
edge = £18+VAT for a few.
(It's ot rocket science - they use spray glue and bob's your insulated
uncle).
> The good thing about Marmox is the waterproof cementitious coating +
> waterproof extruded polystyrene + waterproof cementitious coating.
not much use on the OP's bathroom celing tho
> That means it can "catchup" with PIR+PB performance per unit thickness
> because you can glue it straight to damp solid brick walls and just
> skim it - rather than Baton thickness on top of PIR+PB thickness
You can dot and dab PIR PB straight on without battens.
> For a ceiling, I would go with whatever the local building merchant
> has and screw thro the PB and the PIR into the joists.
That I agree with :>) tho watch the weight if areas/pieces are
large...
JimK
js.b1
> Jewsons? £70 ????? presume you don't have an account then
They do not even stock it, just XPS with PB.
So it has to be special order. Bizzare.
> Try a local insulation specialist - 25mm foiled PIR + 12.5mm taper
> edge = £18+VAT for a few. (It's ot rocket science - they use spray
> glue and bob's your insulated uncle).
I know, will have to hunt around.
> You can dot and dab PIR PB straight on without battens.
Ah, but mention solid wall (not OP) and they run a mile.
A bathroom might need care around the edge to avoid moisture.
> That I agree with :>) tho watch the weight if areas/pieces are
> large...
It is surprisingly heavy.
JimK
> On Nov 19, 9:18 pm, JimK <jk989...@googlemail.com> wrote:
>
> > Jewsons? £70 ????? presume you don't have an account then
>
> They do not even stock it, just XPS with PB.
> So it has to be special order. Bizzare.
>
> > Try a local insulation specialist - 25mm foiled PIR + 12.5mm taper
> > edge = £18+VAT for a few. (It's ot rocket science - they use spray
> > glue and bob's your insulated uncle).
>
> I know, will have to hunt around.
>
> > You can dot and dab PIR PB straight on without battens.
>
> Ah, but mention solid wall (not OP) and they run a mile.
who's "they" Jewson's numptys again?
No "mile running" noticeable here....
http://www.british-gypsum.com/pdf/WB09_DriLyner_02.pdf
see p7
JimK
Andrew Gabriel
Tim W <t...@dionic.net> writes:
> Pete Verdon <ne...@verdonet.organisation.unitedkingdom.invalid>
> wibbled on Wednesday 18 November 2009 23:52
>
>> Andrew Gabriel wrote:
>>> Pete Verdon <ne...@verdonet.organisation.unitedkingdom.invalid> writes:
>>>> Tim W wrote:
>>
>>>>> Are you actively trying to stop heat loss or just reduce the cold
>>>>> surface a bit to lessen condensation?
>>
>>>> The latter.
>>
>>> Even 25mm Cellotex will achieve that.
>>
>> That's good to know.
>>
>> I've never actually handled Celotex before. I had been kind of assuming
>> I'd stick something up and let the plasterer do his thing, but it's
>> dawned on me that plaster probably won't stick to plain Celotex, will it?
>>
>> Pete
>
> No it won't It's (usually) faced in shiney foil.
>
> 30+mm Marmox will probably achieve what you want, though not strictly
> equivalent to 25mm celotex, but we're not working with critical numbers
> here.
>
> If using celotex (or any equivalent product) then you'll need to screw it to
> the ceiling timbers with big washers (they make washers for this purpose).
I just used plasterboard screws (having a large tub of them).
They're only holding up the celotex for just long enough to
fix plasterboard under it, which will then hold it fine.
The other thing I've done (different ceiling) is to cut the
celotex into rectangles to wedge between the ceiling joists,
and no fixings were required. Depends how much headroom you
have and available depth of joists and allowing for ventilation.
In both cases (both bathrooms), I taped over the celotex joins
(and joist edges in second case) with aluminium tape, to make
a moisture-proof seal (and also used foil-backed plasterboard,
although I wouldn't bother going with the pink stuff on a ceiling).
> At this point you'll need to cover it with something that takes plaster.
> Your choices are now plasterboard (moisture resistant - pink - would be a
> good idea), or Marmox or something else with a suitable surface. This would
> be screwed through the celotex into the same timbers.
Tip - mark where the timbers are on the walls, or you won't find
them very easily.
Tim W
wibbled on Sunday 22 November 2009 19:23
> I just used plasterboard screws (having a large tub of them).
> They're only holding up the celotex for just long enough to
> fix plasterboard under it, which will then hold it fine.
That's a useful tip.
> The other thing I've done (different ceiling) is to cut the
> celotex into rectangles to wedge between the ceiling joists,
> and no fixings were required. Depends how much headroom you
> have and available depth of joists and allowing for ventilation.
> In both cases (both bathrooms), I taped over the celotex joins
> (and joist edges in second case) with aluminium tape, to make
> a moisture-proof seal (and also used foil-backed plasterboard,
> although I wouldn't bother going with the pink stuff on a ceiling).
>> At this point you'll need to cover it with something that takes plaster.
>> Your choices are now plasterboard (moisture resistant - pink - would be a
>> good idea), or Marmox or something else with a suitable surface. This
>> would be screwed through the celotex into the same timbers.
>
> Tip - mark where the timbers are on the walls, or you won't find
> them very easily.
>
Indeed :)