Roof insulation - slate roof

[renwaldo]

I have a new build house (3 years old) with a slate roof. As far as I can tell there is no insulation between the rafters but quilted insulation in the loft. Two bedrooms sit within the roof space so the loft is very small.

I am concerned the developer did not put in the correct roof insulation. Should there be something between the rafters as well as the quilted insulation ?

 

[chipchaser]

Hi Renwaldo,

Building Regs Part L1, Conservation of Fuel and Power changed in April 2006. If your house was designed/approved after that date the current regs apply. A detailed answer requires more information but it is possible that your insulation quilt at ceiling joist level is sufficient. Having insulation at ceiling level and insulation between the rafters would not be a preferred solution, that is its normal to do one or the other not both.

Compliance with the regulations is achieved by calculating the Target CO2 Emission Rate and comparing that to a notional building which meets SAP 2005 via a formula which also takes fuel type and lighting into consideration.

As a guide Rockwool say that about 325 to 355mm of Rockwool roll would comply. This would need to be checked as part of a calculation of the energy use of the house as a whole as outlined above. To be more specific, your easiest route would be to ask the builder what was specified.

Regards
Graham