Which model of Kingspan / Celotex is right for me?

[steveharman]

Due to space constraints I need to insulate a room using 25mm (rather than 50mm+) Celotex / Kingspan insulation boards.

But I only have a small brain and am confused by the different product codes Celotex & Kinsgspan use - seemingly different names for identical products depending on their thickness.

For example it _seems_ like I need 25mm "Celotex T-Break TB3000", yet this is often described as "suitable for overcoming localised thermal bridges..." Uh? Is that really what I need to insulate my walls?

Other 25mm boards are described as suitable for roof work but no mention is made of wall use.

Can anyone explain please?

Thanks in advance,

Steve

 

[noseall]

Localised thermal bridges are locations such as window and door reveals, or raked eaves where the rafters are very narrow.

25mm celotex would be used along with a much thicker board, say 100mm across the roof timbers and 25mm between.

25mm celotex will be an improvement but will not satisfy reg's and may not be man enough in extremely cold weather.

 

[steveharman]

At last, someone whose explanation I understood.

Many thanks.

Steve

 

[legs-akimbo]

Celotex T - break sounds like something you would dip in your tea.
Why is there a constaint of adding a single more inch to the wall out of curiosity when the U value of 50mm Therma board (Celotex or Kingspan) would clearly be fit for purpose.....Why spoil the ship for an apeth of tar ?

 

[regsmyth]

Because otherwise the timber studs themselves transfer cold to the inner plasterboard, and condensation will tend to form on the surface of the plasterboard.

 

[legs-akimbo]

Ahh Reg I did not realise you were the next door neighbour who pops around to dip celotex T break in Stevies Coa Coa.
I did not see the constitution of the wall elevations described by Steve so how is it you can assertain that interstitial condensation would be problematic. ?
Only certain types of wall construction persist in causing I.C. problems, mainly single leaf hollow block and cast concrete, cavity construction does not as moisture is allowed to dissipate naturally unlike single leaf construction.
When you pop round tommorrow ask Steve to post up a little more information.

 

[legs-akimbo]

Because otherwise the timber studs themselves transfer cold to the inner plasterboard, and condensation will tend to form on the surface of the plasterboard.

The cold bridging of the timber stud is not the factor that causes interstitial condensation and to claim the density of the board has any bearing is nonsense.
I could explain why but I cant be bothered.

 

[joe-90]

Don't you just love the way legs talks? velociraptor of the forum.

 

[tawelfryn]

celotex/kingspan, all the same different name. rule of thumb, thicker the better, cost per sheet/pack/ more money=better performance=more u value, simples

 

[mattylad]

I flicked through & there was a DIY program on today where "Dave Wellman" (I think) was fitting a foil/foam based sheeting that looked like it was only about 5mm thick, had several layers of foam/foil and was suposed to be 200+ a roll of 20msq, what about that then?

It was used on a wooden constructed external facing wall with t/g cladding on the outside

 

[legs-akimbo]

Have always been very suspicious of this type of multi foil type stuff, seemed that highly contentious claims were made as to its R or U values and many of the products did not have Irish acreditation or British kitemarks, which meant only one thing to me they did not do what it said on the tin.
However was speaking to a guy last week who used this on a new build dormer instead of between rafter and he said it was excellent....Untill I use it for myself I will reserve judgement.
Would certainly be an option to consider for the O.P.

 

[jeds]

I flicked through & there was a DIY program on today where "Dave Wellman" (I think) was fitting a foil/foam based sheeting that looked like it was only about 5mm thick, had several layers of foam/foil and was suposed to be 200+ a roll of 20msq, what about that then?

It was used on a wooden constructed external facing wall with t/g cladding on the outside

Multifoil manufacturers have had problems backing up their claims. There was a TRADA certification a year or two back which was based on a full scale test of timber frame houses built in a warehouse somewhere. But that ran out and wasn't renewed. There have been other independant tests since but none have resulted in across the board acceptance of multifoils by UK building control. The nearest it has got to it is that multifoils can be used to supplement standard PUR foams - you need to go to the particular manufacturers websites to see how much foam and when it can be used.

My own view is that once you start with foam you might as well go all the way. I don't see the point in replacing 50mm of easy to fix and relatively cheap foam with 50 or 60mm of very fiddly to fit, expensive, multifoil.

 

[JohnD]

But that ran out and wasn't renewed. There have been other independant tests since but none have resulted in across the board acceptance of multifoils by UK building control.

If I was selling a product that actually worked, and performed as I claimed, then I'd be very keen to get it tested and certified

On the other hand, if I was selling a product that didn't...

 

[jeds]

That's a fair point John.

It works on the basis of extremely low radiated energy loss from the surface of highly reflective foil. That's why they wrap the Hubble Space Telescope in the stuff. That's all very well in the perfect vacuum of space but here on Earth, where we have air and atmosphere and stuff, heat energy is mostly transmitted by conduction and convection which tin foil is almost useless against. Otherwise our gooses would never be cooked.