Building Regs and Insulation

theGrinch

What is the current requirement in terms of mm for insulation for ceilings, floors and wall in a new extension?

G_M

Building Regulations

Insulation has to comply to the relevant building regulations both when installed during construction or when fitted retrospectively.

• Loft Insulation and building regulations.
• Cavity Wall Insulation and building regulations.
• Solid Wall Insulation and building regulations.
• Floor Insulation and building regulations.
• Other Insulation and building regulations.

https://www.planningportal.gov.uk/permission/commonprojects/insulation/

and

http://www.kingspaninsulation.co.uk/Knowledge-Base/Building-Regulations.aspx

and

http://www.planningportal.gov.uk/buildingregulations/approveddocuments/

chappers

u-values
pitched roof at ceiling level 0.16 equate to 270mm of rockwool which would be the usual method
pitched roof at rafter level 0.18 (90mm celotex between rafters and 50mm insulated plasterboard under rafters with a 50mm ventilated air gap over the insulation)
flat roof 0.18 140mm over rafters and ply deck for a warm roof or 90/100 between and 40/50mm insulated plasterboard under for a ventilated cold roof with 50mm air gap over insulation
wall 0.28 will depend entirely on construction of wall, but for standard brick and block cavity with 100mm cavity then 60mm celotex or full fill with rockwool
floor 0.22 100mm celotex under concrete slab or over slab and under 75mm screed

or check out the celotex site they have a u-value calculator for other constructions

bgm_co

What Chappers said! But if you are over your 25% (of floor area) glazing guide for your construction, you'll need to improve those numbers to suit.

Smiley_Dan

Bear in mind that these figures are worst acceptable standard as deemed by BC.

You should be doing a lot, LOT better than that if at all possible.