Help! Wall insulation

Danny, I posted this just recently............... Just thought I'd share this info with everyone. I've just added a Dormer to a new upstairs room. Basically 4" x 2" (95mm x 45mm) stud

walls. I've 'stuffed' it with the following insulation called Rocksilk

by Knauf. The spec. sheet gives the following details...

UNIVERSAL SLAB RS45 Thickness 100mm (I have also used 75mm)

Length: 1200mm Width: 600mm Area per pack (m^2): 3.6 Lamda (W/mK): 0.035 R Value (m^2K/W): 2.85 Fire ClassSlabs per Pack: A1 Pack per Pallet: 5 Product Code: 2361392

The price for one pack from Sheffield Insulations in Aberdeen was =A332. So that's nearly =A310 per square metre. Quite expensive for what it is. It is good to work with, easily cut with a breadknife. Just cut it about a quarter inch oversize and push between the studs.

Chris.

Cheers for that.

Did you put the DPM behind the insulation, or in front (before the plasterboard)?

Thanks

On 24 Nov 2005 09:44:51 -0800, a particular chimpanzee named "daniel" randomly hit the keyboard and produced:

Hmm. The last question will depend on whether you're converting a porch into a habitable part of the dwelling or whether it was part before. If the latter, then you're not making the situation worse than previously and therefore don't need a Building Regulations application. If the former and you are 'renovating' the walls, roof or floor over a substantial area, you should insulate to a 'reasonable' standard.

To answer your first question; you would be better with a PIR insulation such as Celotex, Kingspan, Xtratherm, etc. between the studs, and a vapour barrier on the _inside_ (polythene or foil backed plasterboard) to prevent condensation from within the building getting into the timbers.

No I didn't as this is effectively an extension of the roof itself so there is roofing felt, then 22mm. sarking boards, then

Chris.

You will get condensation on the sarkin boards. Can you get access from the attic to inspect?

The porch was not part of the dwelling before as there was an exterior grade door between it and the dwelling, so my understanding is that we will have to insulate to a reasonable standard.

Thanks for the advice, I think I'll pack the studs and then use a lined plasterboard as you mentioned.

Ok, seems to be a similar situation to me then.