100 or 120mm celotex - warm roof?

[pilsbury]

i was planning on 100mm. My BC guy said 120mm was the norm. What have others done to achieve the required u values? Standard warm roof construction. Cost is important to me. I'm not after super insulated, just to confirm to regs. The rest of the house is old solid walled, single glazed!

 

[chappers]

120 minimum

 

[Doggit]

I've always been told 135, but would that be 100 between the rafters, and 20+15mm plasterboard over them.

 

[pilsbury]

I've always been told 135, but would that be 100 between the rafters, and 20+15mm plasterboard over them.

Cold roof?

 

[Doggit]

No, warm roof, just a query as to the difference.

 

[John D v2.0]

If there are any rafters in the insulation layer it's not a warm roof. You can get hybrid roofs but even those most of the insulation is on top.

 

[chappers]

I've always been told 135, but would that be 100 between the rafters, and 20+15mm plasterboard over them.

that's why I said 120 minimum, 120 can satisfy BR for a warm roof, depending on type of insulation and fixing methods.

 

[chappers]

.

 

[rssteve]

120mm min to get he u value. I remember a previous post where you said 100mm had been passed on your plans. Guess they've picked that up now though.

 

[noseall]

120mm. Standard.

 

[Notch7]

120mm to achieve a 0.18 u value, thats a warm roof all over the top not inbetween

checkout the kingspan u value calculator

 

[catlad]

Bet you wished you had put more in now that energy prices have doubled!

 

[^woody^]

All insulation is the same.

 

[RonnyRaygun]

All insulation is the same.

Eh??

 

[pilsbury]

Bet you wished you had put more in now that energy prices have doubled!

Ha! It got 120mm….. also now got double glazing in the rest of the house too…. All modern like.

But zero loft insulation as that’s all out as part of the loft conversion.