Making sure your loft conversion is properly insulated is vital for a warm, cost-effective attic. You want to be reassured you’ve got value for your money and that energy isn’t escaping from your roof. There are two ways that loft conversions are typically insulated; ‘cold roof’ and ‘warm roof’ method.
‘Cold Roof’ method
This method is the more straightforward and traditional of the two, though not as energy efficient. It involves leaving a 50mm gap between the insulation layer and the roofing felt. The air in-between this space is kept mobile by fresh incoming air and escaping air, as a flow. The theory is that there will be no condensation as the area is constantly ventilated.
Slab foam insulation, such as Celotex, is typically used for the insulation layer, and you’d need a 70mm thickness for effective insulating. More insulation is also added to the inside of the rafters and the roof section itself needs either mineral wool insulation or thicker Celotex.
‘Warm Roof’ method
This involves covering the entire roof and rafters with insulation, so the roof is kept ‘warm’. There can’t be any gaps in the insulation as the idea is to remove the possibility of warm air coming in contact with a cold surface. When there is a gap, condensation can form and this is called ‘cold bridging’.
Again, Celotex is typically used but 100mm thickness is required. Any internal partition walls also need an insulation layer as do the floor joists. Rockwool fibre is typically used because of the sound reducing function, but quilt insulation is suitable too.
Choosing the right insulation is really important for a cosy loft conversion. The team at J Wolf have over ten years’ experience with loft conversions in South West London so if you’re unsure of what insulation your loft would need, please give us a call on 07832 517516 for a chat or a no-obligation quote.