Building regs insulation guides online?

[festive]

Hi,

after speaking to my building inspector about insulation in my loft room he specified 70mm celotex/kingspan, plus i needed to add battons along my rafters to increase the air gap etc.

I would like to check im doing it all right, is there an online guide or building reg fact sheet for this, ie what i need for a flat dormer roof, does it differ etc.

TIA.

 

[PJ1]

There are no doubt some hard-back guides, but you need to make sure they're upto date as the insulation Regs changed in April 2006. Some Council websites also have guides (under Building Control) but I just couldn't find you one, soz.

The insulation levels required for sloping ceilings and flat roofs are the same at 0.2W/sq.m.K. Dormer walls are 0.3 (lesser standard)
The way you get there is upto you. Cellotex have a good on line calculator. http://www.celotex.co.uk/u-value.asp
Simply put in an email and 'Start the calculator'. It's more efficient to put some insulation between the rafters and then some in full sheets below the timbers, before plasterboarding. They have handy guides you can download as well.
You must have a 50mm an air gap over the insulation and a means to get through ventilation of that void incl.at ridge level for sloping ceiling areas (if you have you have breathable sarking felt, that gap can go down to 25mm).
You can find the Approved Documents to the Building Regs on the Planning Portal. This is the bit for insulation levels to extensions, but there's no pictures! http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2006.pdf