Loft Conversion Insulation Value
Discussion
We are in the process of looking at options for a loft conversion on our house (1930's semi) and I'm struggling to understand in layman's terms what the current Building Reg standards are for this element.
The website below suggest a u-value of 0.18 w/m2k, but I can't get my head round whether this relates to the roof structure as a whole (i.e. combined across the void between the joists and between the sloping trusses) or whether it has to relate to any individual section of the roof (i.e. the insulation between the joists needs to be 0.18, as does the insulation between the trusses).
Hopefully this makes sense! Anybody able to assist?
The website below suggest a u-value of 0.18 w/m2k, but I can't get my head round whether this relates to the roof structure as a whole (i.e. combined across the void between the joists and between the sloping trusses) or whether it has to relate to any individual section of the roof (i.e. the insulation between the joists needs to be 0.18, as does the insulation between the trusses).
Hopefully this makes sense! Anybody able to assist?
tleefox said:
We are in the process of looking at options for a loft conversion on our house (1930's semi) and I'm struggling to understand in layman's terms what the current Building Reg standards are for this element.
The website below suggest a u-value of 0.18 w/m2k, but I can't get my head round whether this relates to the roof structure as a whole (i.e. combined across the void between the joists and between the sloping trusses) or whether it has to relate to any individual section of the roof (i.e. the insulation between the joists needs to be 0.18, as does the insulation between the trusses).
Hopefully this makes sense! Anybody able to assist?
http://www.kingspaninsulation.co.uk/Knowledge-Base/Building-Regulations.aspxThe website below suggest a u-value of 0.18 w/m2k, but I can't get my head round whether this relates to the roof structure as a whole (i.e. combined across the void between the joists and between the sloping trusses) or whether it has to relate to any individual section of the roof (i.e. the insulation between the joists needs to be 0.18, as does the insulation between the trusses).
Hopefully this makes sense! Anybody able to assist?
Assuming England you will need:
0.18 for the ceiling
0.28 for the walls, note that the dwarf wall on a pitched loft conversion counts as wall.
As you are not converting over an unheated space I don't think you need to worry about the floor but check that.
Edited to say, for your roof, assuming 600mm joists, VCL and Plasterboard, you would need 150mm of Celotex FR5000 or equivalent. Don't forget you should leave a ventilation gap of 50mm.
for the dwarf wall, the joist thickness may prevent you installing anything over 100mm so you might need over joist insulation too. I certainly did for my garage conversion.
i can help if you need me to, just an amateur but did my own calcs for Building Control sign off.
Edited by worsy on Wednesday 9th December 15:54
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff