celotex, kingspan, xtratherm

[Fred]

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

[harry]

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.

[ransley]

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

[Jim]

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.

[John Rumm]

On 16/07/2010 10:48, Fred wrote:

> 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?

Mostly - they are usually PIR foam based boards and hence will have
similar insulation values. What differs is what is used to cover them.
Some like celotex also have reinforcement fibre strands that run through
the board ever few inches (not that it does much for you).

The finish is often a foil vapour barrier on at least one side and often
both, although other options include cork and bituminous layers (for
sound deadening), and timber coated on one side (roof decks),
plasterboard (dry lining) etc.

> 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?

If you download the data sheets from the celotex or kingspan sites they
specify ways to do it. (IIRC they include an adhesive layer as well).
However I expect that the commonly available double sided foil boards
would perform adequately in this application.

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

[george [dicegeorge]]

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=_TeJm9EuHkAC&dq=insulate+and+weatherize+bruce+harley&printsec=frontcover&source=bn&hl=en&ei=e5pATMfTL5_40wTTzrSXDw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CCQQ6AEwAw#v=onepage&q&f=false

[g]

[Fred]

On Fri, 16 Jul 2010 15:50:51 +0100, John Rumm
<see.my.s...@nowhere.null> 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.

[John Rumm]

On 16/07/2010 19:14, Fred wrote:
> On Fri, 16 Jul 2010 15:50:51 +0100, John Rumm
> <see.my.s...@nowhere.null> 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

Basically - they also make it harder to cut since they can snag saws
etc. I can't see they add much practical strength in a typical application.

> local depot stocked xtratherm instaed. I'd never heard of that. If it
> is the same thing, then I'll stop worrying then. Thanks.

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

[Hugo Nebula]

[Default] On Fri, 16 Jul 2010 06:15:52 -0700 (PDT), a certain
chimpanzee, ransley <Mark_R...@Yahoo.com>, 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"?

[Fred]

On Sat, 17 Jul 2010 03:30:24 +0100, John Rumm
<see.my.s...@nowhere.null> 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.

[d...@gglz.com]

On 21 July, 21:17, Fred <f...@no-email.here.invalid> wrote:
> On Sat, 17 Jul 2010 03:30:24 +0100, John Rumm
>

> <see.my.signat...@nowhere.null> 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.

[John Rumm]

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.

[Fred]

On Wed, 21 Jul 2010 22:55:14 +0100, John Rumm
<see.my.s...@nowhere.null> 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.

[John Whitworth]

"Fred" <fr...@no-email.here.invalid> wrote in message
news:3g2g465jmh1bqvqsm...@4ax.com...

> On Wed, 21 Jul 2010 22:55:14 +0100, John Rumm
> <see.my.s...@nowhere.null> 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.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "John Whitworth"
<sexyjw@g_EEEEEEEEEEEEEEEE_mail.com> 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]

Some numbers at the end of this:

http://wiki.diyfaq.org.uk/index.php?title=Heat_loss

(PIR foam is about twice as good as traditional quilt)

[John Rumm]

On 22/07/2010 10:10, Fred wrote:

> 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

No need to replace all of it... leave 100nn between the joists (assuming
they are 100mm deep!), and stick say 80mm of PIR foam on top followed by
your floor boards. That will give you the equal of 270mm of quilt.

> 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?

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.
##~~~~~~~~##~~~~~~~~~##
##~~~~~~~~##~~~~~~~~~##

[Chris J Dixon]

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
ch...@cdixon.me.uk

Have dancing shoes, will ceilidh.

[John Whitworth]

"Chris J Dixon" <ch...@cdixon.me.uk> wrote in message
news:9p9i46tega8m509uu...@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

[Jim K]

On 23 July, 12:54, "John Whitworth"
<sexyjw@g_EEEEEEEEEEEEEEEE_mail.com> wrote:
> "Chris J Dixon" <ch...@cdixon.me.uk> wrote in messagenews:9p9i46tega8m509uu...@4ax.com...

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

[John Rumm]

On 23/07/2010 06:24, Chris J Dixon wrote:
> 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?

Yup. While the foam can be damaged by point loads - spread over a joist
with a board over, you can screw the board down through the foam and it
hardly crushes at all. The same construction technique is used for "warm
deck" roofs these days.

[John Rumm]

Its fine - try it. If you stand on a bit, your foot does not sink in.

[m...@privacy.net]

On 23 Jul,
"John Whitworth" <sexyjw@g_EEEEEEEEEEEEEEEE_mail.com> wrote:

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

[Fred]

On Fri, 23 Jul 2010 00:24:49 +0100, John Rumm
<see.my.s...@nowhere.null> 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 ;(

[Fred]

On Thu, 22 Jul 2010 22:34:28 +0100, Grimly Curmudgeon
<grimly...@REMOVEgmail.com> 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.

[Fred]

On Thu, 22 Jul 2010 22:34:28 +0100, Grimly Curmudgeon
<grimly...@REMOVEgmail.com> 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

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the

drugs began to take hold. I remember Fred <fr...@no-email.here.invalid>
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.

[Fred]

On Wed, 21 Jul 2010 22:55:14 +0100, John Rumm
<see.my.s...@nowhere.null> 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

[John Rumm]

On 29/07/2010 10:19, Fred wrote:

> BTW at what point does a sheet become a second? There were some marks

It might be knocked about a bit, or have a void somewhere. Sometimes it
can just be because its an odd shape it seems.

> 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.

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

> 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

yup

> blade? Is it more rigid and therefore stronger?

yup

[Fred]

On Thu, 29 Jul 2010 13:05:59 +0100, John Rumm
<see.my.s...@nowhere.null> 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?

[John Rumm]

On 02/08/2010 15:25, Fred wrote:

> 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.

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

>
>>> 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?

Yup the larger ones tend to be more generally useful. The small one is
handy for opening stuff I suppose, but I don't bother buying them these
days.

> 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?

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

[Jón Fairbairn]

On 2010-08-02, John Rumm <see.my.s...@nowhere.null> 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 Jon.Fa...@cl.cam.ac.uk
http://www.chaos.org.uk/~jf/Stuff-I-dont-want.html (updated 2009-01-31)

[Fred]

On Mon, 02 Aug 2010 23:33:23 +0100, John Rumm
<see.my.s...@nowhere.null> 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.