Loft Insulation Rejected

[salem2000]

Hi

A friend at work is having probs with BRO in regard to roof insulation in her loft conversion.

50mm air gap maintained, 80mm celotex between joists and insulated plasterboard to cover. BRO said not enough and to start again, no info given by him. I don't know how to calculate the U-values so am stuck there.

Would using "Triso Super 10" in addition to the above, achieve the required U-value which I've been told are 0.20 for the roof on the conversion .

Is there a simple way to work out these calcs.

Thanks

Salem.

 

[freddiemercurystwin]

Firstly, try 60mm Celotex between the rafters and 60mm Celotex under the rafters with normal plasterboard under that (in any case you'll need around 120mm total), then go here: http://www.celotex.co.uk/u_value.php

Personally, I'd favour Kingspan as their technical department is better/quicker and I believe its slightly cheaper as Kingspan's a better insulation hence you don't need quite as much. Give their tech helpline a ringo and they'll email you a calc for BR submission.
http://www.insulation.kingspan.com/uk/pdf/k7.pdf
http://www.insulation.kingspan.com/uk/contact.htm

Tri iso is unproven for roof's and is rejected by most building control departments.

 

[alpcon]

If you are thinking of using tri iso super 10 then you do not need any other form of insulation in the void between the roof timbers. It is not recomended that you fit tri iso horizontally, it comes into its own when used on a vaulted roof either under the roof timbers or over the top of them.

With respect to the building inspector I dont think hes being very helpful as any inspector ive ever come across has always been happy to help.

What about the building spec you are using? surely building control have passed this so why the rejection of the insulation. If you have stuck to the spec as passed then you should have no problems.

I need more info to help you more

 

[al4x]

If you want to go down the trisco route thouch check with the Inspector that he will ok it, as its acceptance seems about as clear as mud.

 

[noseall]

if tri iso is licenced to b.b.s. approval, then it is highly likely b.c. will accept it .

if it is not, then they won't.

 

[salem2000]

Thanks for the info, have passed it on and hope she gets a result.

Salem