Reflective Insulation

How are insulation and ventilation dealt with in a loft conversion?

When a loft has not been converted, you are supposed to put insulation on the floor of the loft. There also has to be ventilation under the eaves to prevent condensation. But when a loft has been converted to an extra room, what should be done about insulation and ventilation? I suppose you would remove the insulation on the loft floor, because you no longer want to prevent heat entering the loft, so would you insulate the sloping roof itself? And you would not want a breeze flowing through the loft, so would you cut down on the ventilation?

Public Comments

1. The sloping timbers on a roof are called rafters, a lot of the time they are 100mm from edge to edge but when converting a loft building control say that we have to put 90mm foil backed insulation between the rafters while still maintaining a 40mm gap for airflow, additional timbers are fixed to the under side of the rafters to obtain the extra 30mm or so needed to fulfil their requirements. Having done that they say that we then need to fix 30mm foilbacked insulation covering the complete underside of the rafters before fixing the plasterboard to eliminate any coldness that would normally occur if the plasterboard was in direct contact with the rafter, this is refered to as a "Cold bridge" As for the insulation in the floor, there is no direct regulation as far as I can remember however I tend to insulate it more for the purpose of sound proofing rather than heat. Hope this helps, Let me know if you need me to expand on anything.