What are my insulation choices here please?

[Franalogue]

New build with room in roof trusses. I am confused as to what meets regs. Can I have insulation boards just between the trusses (eg Celotex or Kingspan) with plasterboard over or do I have to also have some over this, intruding into the habitable space thus reducing the room sizes up there. I have emailed the building inspector and I can't make head nor tail of his reply. If I want to use foiled boards, what size please? Can I use an 'on a roll' type or batts? Just want to know what's acceptable as I probably can't afford to insulate it all in one go and will have to buy it in dribs and drabs as I go along. If I know my choices I know what to look out for basically. Thanks in advance.

 

[Ian H]

I think the standard is 100mm Celotex between the rafters and 50mm Celotex below them, then plasterboard.

The foil boards aren’t for insulation, they are to stop moisture.

 

[endecotp]

I probably can't afford to insulate it all in one go

Have you discovered Seconds & Co for cheap kingspan?

 

[Franalogue]

Hi, OK so 100mm between rafters and 50mm in the upright bit. Yes I will be looking at the Seconds and Co bundles on Ebay as i go along thanks.

Thanks for the replies.

 

[^woody^]

Seconds is crap, and not that cheap for what are broken and dented boards. Ask for a discount from your local supplier.

 

[garyo]

Hi, OK so 100mm between rafters and 50mm in the upright bit. Yes I will be looking at the Seconds and Co bundles on Ebay as i go along thanks.

Thanks for the replies.

100mm between rafters and uprights, plus 50mm beneath rafters and over uprights.

 

[Ian H]

I’m following this guy to see if any falls out

 

[^woody^]

Pervert

 

[pilsbury]

I’m following this guy to see if any falls out
View attachment 148803

Are illegal immigrants good insulators?

 

[Ian H]

Are illegal immigrants good insulators?

Yes, you can fit loads of them between the rafters

 

[Franalogue]

OOooh I hadn't though about using illegals. They would keep it warm up there is there is enough of them.

 

[endecotp]

Seconds is crap, and not that cheap for what are broken and dented boards.

They seem to have various different offerings. Here is my experience; others may differ.

I got some of their “stock” seconds boards, which look virtually perfect to me. No dents or cracks, but just a few wrinkles in the foil. Pricewise, for example a 70/80mm Kooltherm board is £38+VAT+delivery, compared to about £58+VAT+delivery from Insulation Superstore (whose prices are generally some of the better ones I’ve found). The Travis Perkins online price is £91.13.

They also have the advantage of actually being in stock.

Then they have their palettes of bargain boards. These have been stored outside and are clearly in much worse condition. Someone here said they were “cheaper than sand” so if you were doing a floor slab maybe that would be a possibility?

Ask for a discount from your local supplier.

That didn’t work for me.....

 

[pilsbury]

I got a smashing deal on seconds. 120mm boards at about £20/sheet. A hefty saving when you need 15 of them. Mine had no foil so I simply added a cheap plastic VCL. Some edges duffed but who cares? Chop them off.

 

[Ian H]

Are they still pretending there’s a worldwide shortage?