Detail of IWI on single skin / half brick wall for picky building control

[Bruce]

We are insulating our conservatory to bring it into the heated envelope of the house and was going to use the SWIP system but our building control won't approve of it as SWIP have their BBA certification done on a double brick wall rather than just one brick. It is also rather expensive with not great insulating performance but I was prepared to take that hit but I just feel deflated by the retraction of approval from the BC.

 

So I am abandoning the idea of having a vapour open insulation and will go with a more traditional PIR insulated wall. But to make them happy, I need to submit a detail of what we are going to do. What I want is something similar to the one below from Kingspan but I want it to be PIR manufacturer agnostic or from a manufacturer that doesn't charge £350 for two sheets of insulation. I really like how simple it looks. Has anyone done this with Celotex GA4000, how do I do that and make BC happy?

 

Alternatively, we could do the stud system based on below Celotex system (but this one seem outdated and cannot find an updated version). But using a timber stud wall like that, how do you create the distances needed to create the cavity, just blocks on treated timber?

Any help appreciated.


 

 

 

[torre]

Have you asked SWIP for their help? Solid walls are likely to be common for their product so maybe they can clarify their certification or submit some argument to help you engage with BC.

 

It's also worth checking with a specialist supplier like Mike Wye or Lime if their systems are BBA approved. alternatively ask Celotex for a detail. Most insulation suppliers have pretty helpful technical departments

[SimonD]

You used to be able to use LABC approved construction details but since recent updates of Part L, for example, they're no longer in use. Ty Mawr used to have a load of them for their systems. But, I think your BC may need some guidance as there is no requirement that systems must have a BBA cert. The system just needs to be designed by a suitably competent person to show it complies with relevant standards. 

[Redbeard]

21 minutes ago, SimonD said:

But, I think your BC may need some guidance as there is no requirement that systems must have a BBA cert.

 

Very true, but a lot of authorities used it as a 'short cut'.

[sgt_woulds]

Yes, but you can push back.  In my experience, most BCO aren't up to date with current regulations anyway, so going back with a reasoned argument and references to the regulations will mollify them.

 

Our standard responce to BBA questions for our woodfibre insulation:

 

We don’t have a BBA for our wood fibre boards and It is not mandatory to carry this certification for building regulations compliance; regulation 7 (1) states that  CE marking and the appropriate Declaration of Performance can be used to establish the suitability of a product for its intended use. 

 

Additional national or international technical specifications are referenced in Section 1.14 and Independent certification schemes are in Section 1.15.  These are not mandatory and it is stated that they ‘may be in addition to, but not conflict with, CE marking’.

 

Our products are all CE-marked, and the DOP information is available on our website

 

 

I would suggest to get a WUFI calculation for whichever system BRUCE chooses.  This should also help with BCO approval.

 

Back to Earth offer WUFI assessments for their IWI systems - I'm sure they will try to pursuade you away from unnatural insulations to more healthy options though... 🙂

 

 

[Nickfromwales]

Is the roof being converted too? If not, insulating the walls is pointless. 

[SimonD]

3 hours ago, sgt_woulds said:

Yes, but you can push back.  In my experience, most BCO aren't up to date with current regulations anyway, so going back with a reasoned argument and references to the regulations will mollify them.

 

Our standard responce to BBA questions for our woodfibre insulation:

 

We don’t have a BBA for our wood fibre boards and It is not mandatory to carry this certification for building regulations compliance; regulation 7 (1) states that  CE marking and the appropriate Declaration of Performance can be used to establish the suitability of a product for its intended use. 

 

Additional national or international technical specifications are referenced in Section 1.14 and Independent certification schemes are in Section 1.15.  These are not mandatory and it is stated that they ‘may be in addition to, but not conflict with, CE marking’.

 

Our products are all CE-marked, and the DOP information is available on our website

 

 

I would suggest to get a WUFI calculation for whichever system BRUCE chooses.  This should also help with BCO approval.

 

Back to Earth offer WUFI assessments for their IWI systems - I'm sure they will try to pursuade you away from unnatural insulations to more healthy options though... 🙂

 

 

 

I used the European Technical Assessment certification for our woodfibre which was fine by our BC who had never come across the stuff before. I still have yet another stern conversation to have with the building warranty underwriters mind you.