Meeting 0.18 K /mk

[dcfctillidie]

Hi ,

What is the most economical way of gaining 0.18K/mk or below on a new extension without internal insulated plaster boards.

 

[noseall]

Hi ,

What is the most economical way of gaining 0.18K/mk or below on a new extension without internal insulated plaster boards.

Economical on space or £££'s?

We use rebated Unilin full fill 90mm boards, where space is a premium. It means we can build with a 100mm cavity.
Wall make up = 100mm 3.5n Fibolites/100mm cavity/105mm brickwork. Megabucks

Or go with 150mm cavities and use the much more affordable and user friendly fibreglass cavity batts or slabs.
Wall make-up 100mm 3.5n Fibolites/150mm cavity/105mm brickwork. Affordable.

 

[tony1851]

Some builders are now using studwork for the inner skin, maintaining the 50 cavity, and filling the space between the studs with 90 PIR, but it needs 32.5 mm insulated plasterboard internally.
The relentless increase in U-values is becoming ridiculous and using up valuable space, critical where small infill extensions are being built.