Couple of PIR insulation board questions

[d000hg]

Looking around insulation seconds I have seen this: https://www.secondsandco.co.uk/product-page/105-110mm-1-2x2-4m-foil-tissue-kooltherm-sheet
Foil on one side, tissue on the other. I can't even find this particular product online does anyone know what it is, if it has a special application, and where it would/would not be suitable?

My other query was about PIR board sold for cavity part-fill applications. Is this any different from what you'd use in full-fill... seems to just be foil on both sides?

The 3 areas I'm putting my order together for are:

• 100/120mm insulation between joists in a suspended wooden floor. So the base will be open to the air
• 75mm insulation in a stud wall against an external solid timber wall. I'm leaning towards solid-fill i.e. pressed against the wall with an interior VCL under the plasterboard.
• 100/120mm insulation warm roof i.e. a solid layer of PIR on top of a VCL

I would prefer to buy the same stuff for roof and floor if possible, for the wall I'd like to go with 1.2x.45m boards and just build the stud around them.

I figure I want foil anywhere it is exposed to air or possible damp... what else is important?

 

[d000hg]

BTW spoke to Kingspan and they think it's K106.

They confused me recommending TR26 for my roof and TP10 for the floor. When I asked about the difference since they look identical online, it simply seems to boil down to "that's what it's rated for".

On the other hand Celotex seem to recommend their same product for all scenarios pretty much. Would you expect these things to really matter in terms of building control? When I phone up my builder's yard to ask for pricing they just say "kingspan" which suggests builders aren't specifying very closely?

 

[Adam182]

In terms of building regs its the thickness that counts,

I did a bunch of research for my renovation and came to the conclusion aslong as you buy the required thickness they are all pretty much the same, just get whichever is cheapest.

 

[John D v2.0]

If the foil is facing into a void then it has a small addition to the u value based on it being a low emissivity surface. Also it doubles as a vcl.
The tissue faced sounds like it's designed for direct plastering or rendering or something. You couldn't stick any wet materials to the foil but tissue would be alright.
Won't affect the u value of the main body of it though, unless they did something to improve the compressive strength or something

 

[d000hg]

Cool. Seconds and co had some great deals on today so I bought a load of foil faced PIR for (seemingly) a song. No idea which brand until it arrives but I came to the same conclusion: it's basically the same stuff.

Here's a question: what if you want to insulate the OUTSIDE of a wall? PIR board has very low moisture absorption but clearly isn't suitable for rain exposure. Does anyone make a product that is, or how would you use PIR on this scenario... Assuming appearance is of little importance, some hidden back wall.

 

[John D v2.0]

On ours the external insulation was polystyrene with fibreglass mesh on it and render. I'm not sure if that's best practice, but it did the job.
On grenfell they used external pir insulation with a ventilated rain screen....

 

[Notch7]

Assuming appearance is of little importance, some hidden back wall.

Insulation, then 50 x 25mm battens, then cement rendaboard -but just paint the surface dont bother rendering.