Hi,

Would I be right to think that celotex, kingspan, and xtratherm are
all pretty much the same and 50mm of one is as good as 50mm of
another, or is one better than the other?

Daft question #2: if attaching to an exterior wall to add insulation,
should the foil side face the exterior wall or the inside of the room?

TIA

Fred
wibbled on Friday 16 July 2010 10:48

Hi,

Would I be right to think that celotex, kingspan, and xtratherm are
all pretty much the same and 50mm of one is as good as 50mm of
another, or is one better than the other?

If the base substance is the same, then basically, yes. There might possibly
be variations in foam density for different applications.

The only other thing to check is if the product has the required fire
retardent (ie non spreading/self extinguishing) properties for the
application.

Daft question #2: if attaching to an exterior wall to add insulation,
should the foil side face the exterior wall or the inside of the room?

TIA

I though they were usually foil faced on both sides? My BallyTherm board is.

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On Fri, 16 Jul 2010 10:58:50 +0100, Tim Watts wrote:

I though they were usually foil faced on both sides? My BallyTherm board is.

Perhaps they are. I've never bought any before but am about to place
my first order. If so, that would stop me worrying about which way
round was the right way! BTW are the ebay sellers the best for price
and service? They all seem to offer free nationwide delivery and I am
pretty sure they are all just agents fro builder's merchants.

On 16 July, 10:48, Fred wrote:
Hi,

Would I be right to think that celotex, kingspan, and xtratherm are
all pretty much the same and 50mm of one is as good as 50mm of
another, or is one better than the other?

Daft question #2: if attaching to an exterior wall to add insulation,
should the foil side face the exterior wall or the inside of the room?

TIA

The stuff is incredibly expensive but you can buy seconds. They are
seconds because of mechanical damage or they have large voids oin the
foam. This can be fixed with "canned foam"
http://www.secondsandco.co.uk/
I have bought hundreds of these. Excellent. They deliver too. About
half price.

On Jul 16, 4:48*am, Fred wrote:
Hi,

Would I be right to think that celotex, kingspan, and xtratherm are
all pretty much the same and 50mm of one is as good as 50mm of
another, or is one better than the other?

Daft question #2: if attaching to an exterior wall to add insulation,
should the foil side face the exterior wall or the inside of the room?

TIA

Polyisocyanurate has the highest R value pf 7.2" initialy, it is rated
here at R6.7 or so as it looses some R value as it cures, its the
product that is foil faced here in the US. Polystyrene is about
R5"-5.5", and the white foamboard R 4-4.5" With the added value of a
foil radiant barrier Polyisocyanurate is the best beal. Liqued foams
are the same, they vary depending on type from R4 - R 7 per inch

On 16/07/10 13:12, Fred wrote:
Perhaps they are. I've never bought any before but am about to place
my first order. If so, that would stop me worrying about which way
round was the right way! BTW are the ebay sellers the best for price
and service? They all seem to offer free nationwide delivery and I am
pretty sure they are all just agents fro builder's merchants.

FWIW it's worth getting an insulation contractor to quote as well (if
you can find a proper one that can with jobs that don't consist of just
rolling out loft roll).

We found one that would supply & fit for less than it would have cost us
to buy in the insulation ourselves (even at ebay prices). Which was a
bit counterintuitive - something to do with bulk buying discounts I
would imagine.

On 16/07/10 10:48, Fred wrote:
Hi,

Would I be right to think that celotex, kingspan, and xtratherm are
all pretty much the same and 50mm of one is as good as 50mm of
another, or is one better than the other?

Daft question #2: if attaching to an exterior wall to add insulation,
should the foil side face the exterior wall or the inside of the room?

TIA
Vapour barrier should be on the warm side to stop 'dew' forming as water
vapour permeates through it - so in england on the inside,
in the tropics if its for keeping cool then on the outside.

Insulate & Weatherize (Taunton's Build Like a Pro) [Paperback]
Bruce Harley

http://books.google.com/books?id=_Te...page&q&f=false

[g]

On Fri, 16 Jul 2010 15:50:51 +0100, John Rumm
wrote:

Some like celotex also have reinforcement fibre strands that run through
the board ever few inches (not that it does much for you).

So these threads are supposed to strengthen the board but do nothing
to affect the u-vales? I was hoping to buy celotex but I was told the
local depot stocked xtratherm instaed. I'd never heard of that. If it
is the same thing, then I'll stop worrying then. Thanks.

[Default] On Fri, 16 Jul 2010 06:15:52 -0700 (PDT), a certain
chimpanzee, ransley , randomly hit the
keyboard and wrote:

Polyisocyanurate has the highest R value pf 7.2" initialy, it is rated
here at R6.7 or so as it looses some R value as it cures, its the
product that is foil faced here in the US. Polystyrene is about
R5"-5.5", and the white foamboard R 4-4.5" With the added value of a
foil radiant barrier Polyisocyanurate is the best beal. Liqued foams
are the same, they vary depending on type from R4 - R 7 per inch

In SI units, polyisocyanurate (PIR) has a conductivity value (k-value)
of 0.023W/mK. Divide the thickness by the k-value to get the R-value,
so 50mm thickness gives an R-value of 2.17m^2K/W.

American R-values are effectively resistivity values, as they are
expressed as Rnn per inch, which is a) a little misleading and b) not
entirely accurate, as some materials have different resistances as
they get thicker.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have I strayed"?

On Sat, 17 Jul 2010 03:30:24 +0100, John Rumm
wrote:

Loads of people make PIR foam boards... (ecotherm, ruberoid, and plenty
of others) they all do much the same thing.

Thanks everyone. After all that they delivered Celotex. Now to cut it;
what's best: a fine toothed saw or a knife? I was thinking a snap off
knife extended to the depth of the board but is that safe? the
instructions say not to extend the blade very far.

On 21 July, 21:17, Fred wrote:
On Sat, 17 Jul 2010 03:30:24 +0100, John Rumm

wrote:
Loads of people make PIR foam boards... (ecotherm, ruberoid, and plenty
of others) they all do much the same thing.

Thanks everyone. After all that they delivered Celotex. Now to cut it;
what's best: a fine toothed saw or a knife? I was thinking a snap off
knife extended to the depth of the board but is that safe? the
instructions say not to extend the blade very far.

Snap off knife perfectly ok, but I found a tenon saw best of all -
saw, saw, saw down the line, thump it to free last bits, then once it
flaps over - use the blade on the remaining foil layer.

wibbled on Wednesday 21 July 2010 22:28

On 21 July, 21:17, Fred wrote:
On Sat, 17 Jul 2010 03:30:24 +0100, John Rumm

wrote:
Loads of people make PIR foam boards... (ecotherm, ruberoid, and plenty
of others) they all do much the same thing.

Thanks everyone. After all that they delivered Celotex. Now to cut it;
what's best: a fine toothed saw or a knife? I was thinking a snap off
knife extended to the depth of the board but is that safe? the
instructions say not to extend the blade very far.

Snap off knife perfectly ok, but I found a tenon saw best of all -
saw, saw, saw down the line, thump it to free last bits, then once it
flaps over - use the blade on the remaining foil layer.

I used a wavey breadknife (not serrated). Serrated cuts really well, but
makes a lot of dust. Wavey knife was harder through the foil, but made for
less mess.

Some people like saws - that'll drop a lot of dust and crumbs (not too good
to be breathing a lot of those in - not toxic, but it is classed as a
mechanical respiratory irritant, so basic dust mask advisable). The good
news is that the dust/crumbs are clean and not sticky and a domestic hoover
sorts them out wonderfully without knackering itself.

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On Wed, 21 Jul 2010 22:55:14 +0100, John Rumm
wrote:

I use either a snap off blade knife with extended blade, or a general
purpose jack saw. The latter is better for fiddly bits and cutouts. The
former makes no dust.

Thanks everyone for your help again.

I hadn't discovered celotex when I insulated my loft some years ago,
so I bought those rolls of insulation. I did see some "spaceboard",
which I think is celotex without the foil, and it said that one sheet
was equivalent to so many millimetres of rolled insulation but I can't
remember how many. Does anyone know the equivalence?

IIRC the recommendation is to use 270mm of roll insulation (what is
the proper name for it- rockwool?); how much celotex would that be
equivalent to?

I would like to board the loft to make storage space and if I replaced
the rolls for celotex, that would give me more head room but it seems
a shame to replace all those rolls. Is there a second hand market on
ebay for them I wonder! One advantage of the rolls is that by having
two layers perpendicular, they cover the joists. If I cut celotex into
the gaps between the joists, is the heat loss through the joists
significant? Is it still best to cover them?

Thanks again.

"Fred" wrote in message
...
On Wed, 21 Jul 2010 22:55:14 +0100, John Rumm
wrote:

I use either a snap off blade knife with extended blade, or a general
purpose jack saw. The latter is better for fiddly bits and cutouts. The
former makes no dust.

Thanks everyone for your help again.

I hadn't discovered celotex when I insulated my loft some years ago,
so I bought those rolls of insulation. I did see some "spaceboard",
which I think is celotex without the foil, and it said that one sheet
was equivalent to so many millimetres of rolled insulation but I can't
remember how many. Does anyone know the equivalence?

IIRC the recommendation is to use 270mm of roll insulation (what is
the proper name for it- rockwool?); how much celotex would that be
equivalent to?

BCO told me that Celotex was equivalent to roughly twice the thickness of
normal insulation. I.e. 150mm Celotex = 300mm roll insulation etc.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "John Whitworth"
saying something like:

BCO told me that Celotex was equivalent to roughly twice the thickness of
normal insulation. I.e. 150mm Celotex = 300mm roll insulation etc.

The numbers will tell for sure, but I have a recollection of 100mm
fibreglass = 50mm aeroboard = 25mm Kingspan.
However, and it's a big however - the insulation values claimed for
Kingspan, Celotex, et al, only apply if the fit is perfect. Air leaks
around the sides reduce its effectiveness considerably, which probably
takes it into line with your BCO's estimate.

John Rumm wrote:

Using the PIR over the top of the joists is the best way. No titting
about cutting it to shape then!

So in cross section:

wwwwwwwwwwwwwwwwwwwwwww ---- loft boarded floor
ccccccccccccccccccccccc
ccccccccccccccccccccccc ---- PIR foam
ccccccccccccccccccccccc
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~## ---- joists with quilt infill.
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~##

Just to clarify, there has been lots of discussion elsewhere
about various methods of constructing raised floorboard support.
Are you saying simply perch them on to of the PIR foam?

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.

"Chris J Dixon" wrote in message
...
John Rumm wrote:

Using the PIR over the top of the joists is the best way. No titting
about cutting it to shape then!

So in cross section:

wwwwwwwwwwwwwwwwwwwwwww ---- loft boarded floor
ccccccccccccccccccccccc
ccccccccccccccccccccccc ---- PIR foam
ccccccccccccccccccccccc
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~## ---- joists with quilt infill.
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~##

Just to clarify, there has been lots of discussion elsewhere
about various methods of constructing raised floorboard support.
Are you saying simply perch them on to of the PIR foam?


You can certainly put T&G floorboards directly onto PIR when that PIR is on
a flat surface. However, I am not sure how it would perform if the PIR was
sitting on joists itself.

JW

On 23 July, 12:54, "John Whitworth"
wrote:
"Chris J Dixon" wrote in messagenews:9p9i46tega8m509uung8u2l71humk9p2of@4ax .com...



John Rumm wrote:

Using the PIR over the top of the joists is the best way. No titting
about cutting it to shape then!

So in cross section:

wwwwwwwwwwwwwwwwwwwwwww ---- loft boarded floor
ccccccccccccccccccccccc
ccccccccccccccccccccccc ---- PIR foam
ccccccccccccccccccccccc
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~## ---- joists with quilt infill.
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~##

Just to clarify, there has been lots of discussion elsewhere
about various methods of constructing raised floorboard support.
Are you saying simply perch them on to of the PIR foam?

You can certainly put T&G floorboards directly onto PIR when that PIR is on
a flat surface. However, I am not sure how it would perform if the PIR was
sitting on joists itself.

JW

given that it's a loft and shurely the boards would be screwed through
into the joists -- how much "action" is it likely to get/suffer from?
any point loads spread by chip and PIR onto several joists - maybe a
bit of compression on joists in well used hatch areas possibly? worth
a test tho - it's firm stuff (kingspan partic - Xtratherm seems softer
but not a lot)

Jim K

On 23 Jul,
"John Whitworth" wrote:



"Chris J Dixon" wrote in message
...
John Rumm wrote:

Using the PIR over the top of the joists is the best way. No titting
about cutting it to shape then!

So in cross section:

wwwwwwwwwwwwwwwwwwwwwww ---- loft boarded floor
ccccccccccccccccccccccc
ccccccccccccccccccccccc ---- PIR foam
ccccccccccccccccccccccc
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~## ---- joists with quilt infill.
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~##

Just to clarify, there has been lots of discussion elsewhere
about various methods of constructing raised floorboard support.
Are you saying simply perch them on to of the PIR foam?


You can certainly put T&G floorboards directly onto PIR when that PIR is on
a flat surface. However, I am not sure how it would perform if the PIR was
sitting on joists itself.

JW

I've put mine (actually T&G chipboard) exactly like John's ascii art above.
No problem. It may be a problem below a floor in a habitable room, but for
usual loft storage it's fine.

--
B Thumbs
Change lycos to yahoo to reply

On Fri, 23 Jul 2010 00:24:49 +0100, John Rumm
wrote:

Using the PIR over the top of the joists is the best way. No titting
about cutting it to shape then!

So in cross section:

wwwwwwwwwwwwwwwwwwwwwww ---- loft boarded floor
ccccccccccccccccccccccc
ccccccccccccccccccccccc ---- PIR foam
ccccccccccccccccccccccc
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~## ---- joists with quilt infill.
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~##

Thanks for all the replies.

I was going to ask whether you needed something between the joists and
the insulation boards but other people have beaten me to that. I had
always thought (wrongly) that it would crush where the weight was
applied over the joists and it's too expensive to tread on some to see
what happens!

I have seen spaceboard in the shops and always thought it was an
expensive way of buying small blocks of PIR but according to their web
site, I was surprised to see it is a type of polystyrene:

http://www.space-insulation.com/board.html

The only disadvantage with the arrangement above is that I still lose
some headroom, albeit less than if I used rolls. I think we've agreed
that PIR requires half the thickness of a roll.

I'm still curious whether I could fill with celotex between the joists
to maximise headroom or would the heat losses through the joists be
too much? Do they really need to be covered?

I'm afraid that whatever I do, I will have to "tit about" because I've
got one of those roofs with "W" shaped trusses on every joist ;(

On Thu, 22 Jul 2010 22:34:28 +0100, Grimly Curmudgeon
wrote:

However, and it's a big however - the insulation values claimed for
Kingspan, Celotex, et al, only apply if the fit is perfect. Air leaks
around the sides reduce its effectiveness considerably,

I suppose it should be no surprise that the marketing department use
the best figures ;(

I'm surprised that a small gap can half the effect of the insulation
though. Ouch! That's a big drop. Does the usual advice apply: spray
expanding foam into any gap 1cm?

I suppose the same is true for whatever insulation you use though?
Surely if you used rolls and left a gap the air space would reduce the
effect of the insulation there too.

On Thu, 22 Jul 2010 22:34:28 +0100, Grimly Curmudgeon
wrote:

Air leaks
around the sides reduce its effectiveness considerably,

Sorry but I've thought about this some more, isn't there a problem
when using celotex between joists that some gaps around the sides are
inevitable?

I'm thinking that the spacing between the joists may vary along its
length by a few mm so you would have to measure carefully and cut
trapezoids to fit. And wouldn't you need an occasional hole to pass
the lighting circuit through? Or do you fill around the cable with
caulk to make airtight? I presume T&E and PIR is ok, unlike T&E and
polystyrene?

TIA

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Fred
saying something like:

Air leaks
around the sides reduce its effectiveness considerably,

Sorry but I've thought about this some more, isn't there a problem
when using celotex between joists that some gaps around the sides are
inevitable?

It just requires a bit of care in cutting and trimming down - the foam
gun is handy, as you say, when there's a gap.

I'm thinking that the spacing between the joists may vary along its
length by a few mm so you would have to measure carefully and cut
trapezoids to fit. And wouldn't you need an occasional hole to pass
the lighting circuit through? Or do you fill around the cable with
caulk to make airtight? I presume T&E and PIR is ok, unlike T&E and
polystyrene?

I've seen foam, wads of f/glass, r/wool stuffed in holes - not perfect,
but apparently good enough. On some jobs the gaps were left bare - I
wonder if the people who were paying for those jobs knew quite how much
better it could have been.

On Wed, 21 Jul 2010 22:55:14 +0100, John Rumm
wrote:

I use either a snap off blade knife with extended blade, or a general
purpose jack saw. The latter is better for fiddly bits and cutouts. The
former makes no dust.

I've fitted it in my wall now and will think about doing the roof
another time. It has occurred to me that if you did the whole loft
insulation in celotex you would need ~150mm, so you would need two
layers any way, so whether I use celotex/celotex or rockwool/celotex,
there are still going to be two layers and the joists will be covered
either way, so I guess I don't need to worry about losses through the
joists.

I did have some cut-offs of 50mm celotex and trod on them; you are
right they do not crush. The foam is tougher than it looks.

BTW at what point does a sheet become a second? There were some marks
on the foil of mine but isn't that inevitable? I did reject one sheet
of 25mm which was squashed where it had been tied to the pallet and
was completely bent along its length. I did get a couple of "you won't
see it when it's in the wall" comments before they finally agreed to
swap it. I think some of the 50mm sheets look wider at the edges than
in the middle. Is that a side-effect of the manufacturing process, is
there always some curl at the edge? They were from a subsidiary of
Travis Perkins so it wasn't some fly by night shop I bought them from.

I didn't have snap-off knife so I used a kitchen knife (don't know
what type but it was a long one!) and it worked ok. Next day I bought
a snap-off knife. I see you can get 9mm, 18mm, 20mm blades. I guess
this is the height of the blade? What is the advantage of a taller
blade? Is it more rigid and therefore stronger?

TIA

On Thu, 29 Jul 2010 13:05:59 +0100, John Rumm
wrote:

Might be down to how they are stored. Many boards come with instructions
to keep under cover - yet many places store them outside.

They were taped onto a pallet to stop them blowing away. The 25mm one
got the tape wrapped around it, and this crushed it to less than 25mm!
That was definitely a second imho but I did have someone on the phone
and the driver grumble about swapping it!

They were saying you won't see it when it's in the wall but my line of
thought is that if I get a second, I should pay for a second, not for
a "first" and surely it being crushed to less than 25mm would affect
its performance.

Never mind, it was swapped the next day.

blade? Is it more rigid and therefore stronger?

yup

I got an 18mm knife. Is that a good size for general DIY use? Is there
ever a time that a smaller or bigger one is better?

I don't know why I never thought to use a saw. Only after I had
finished did I use a saw on an off cut and it went through it like a
hot knife through butter; much easier than the kitchen knife. If only
I had done that before!

How many tpi does the official celotex saw have?

On 2010-08-02, John Rumm wrote:
On 02/08/2010 15:25, Fred wrote:
How many tpi does the official celotex saw have?

Never seen an official one. A standard hardpoint jacksaw seems to work
fast enough.

I've cut xtratherm with two types of jigsaw blades, a long
wood-cutting toothed blade, and the a Bosch T313AW "special
for soft material" with a scalloped cutting edge. They both
cut fast enough, but the amount of dust produced by the wood
blade was enough to be a nuisance, (it gets
electrostatically charged and sticks to everything). The
scallop-edged blade does produce dust, but *much* less.


--
Jón Fairbairn
http://www.chaos.org.uk/~jf/Stuff-I-dont-want.html (updated 2009-01-31)

On Mon, 02 Aug 2010 23:33:23 +0100, John Rumm
wrote:

I doubt a bit of crushing makes that much difference...

It must eventually make a difference because if crushed enough. This
really was a bent and squashed all over the place. Even if the damage
had not affected its u-value, it certainly was not "first" grade.
Since I was paying for "firsts", I didn't want to be sent a second!

I was gluing it into the window reveal so I wanted it to be as
straight as possible.

Never seen an official one. A standard hardpoint jacksaw seems to work
fast enough.

There is one but I have been too lazy to register on the celotex site
to read the spec. It's also listed on the toolstation web site but
they don't go into details. I wasn't going to buy one especially but I
thought if I knew the tpi, I could match it to the nearest saw I had
next time.