Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam.
Pitched roof u value requirement.
U value requirement external walls 0 18 w m k.
U value requirement party walls 0 0 w m k.
The below drawing shows the u value requirements set out for new properties in the building regulations for each element walls floors and roofs.
U value requirement floor 0 13 w m k.
Element u value w m2k walls 0 30 floors 0 22 flat roof or roof with integral insulation 0 20 pitched roof insulation at ceiling level 0 16 pitched roof insulation at between rafters 0 20 windows roof windows and roof lights 1 80 doors with more than 50 of the internal surface area glazed 2 20 other doors 3 00.
Note the distinction between the domestic and non domestic columns.
The u value requirments for building elements are outlined in part l.
U value requirements the u value of a building element i e walls floors or roofs is a measure of the thermal efficiency or heat loss through that element the lower the u value the better the thermeal efficiency of the element.
Typically the u value requirement of a pitched roof is 0 18 w m2k which you could achieve with your 150mm between the rafters and another 12mm fixed under the rafters.
Pitched roof with insulation between ceiling joists or between rafters determine the thickness of the insulation layer required to achieve a u value of 0 21 w m2k if insulation is between the joists and 0 26 w m2k if insulation is between the rafters.
U value requirement opaque doors 1 0 w m k.
Of the building regulations 2007.
The required u value will depend on the location of the project england scotland or wales type of building domestic or non domestic and the application floor wall or roof.
U value requirement roof 0 13 w m k.
Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation.
The new maximum u values are.
The actual specification required for a compliant building and necessary building fabric u value targets may vary depending on the actual overall proposed specification and the outcome of the energy.
U value requirement semi glazed doors 1 2 w m k.
