Polystyrene insulation boards

[tomtomgo]

Hi there,

I want to insulate my roof to save on heating bills. The floor in my loft is already insulated with deck boards covering it.

Our loft will never get converted so with rafters that are 100mm deep and with modern breathable felt is it acceptable to use 75mm thick polystyrene sheets leaving a 25mm air gap behind them and then a 50mm 'cold roof' at the top the insulation boards to aid air flow?

I don't want a rubber stamp approval just want to see if this is practical and something people in the trade do for customers.

Cheers,

Tom

 

[freddiemercurystwin]

There is no advantage whatsoever in insulating the roof at rafter level. Insulate at ceiling level only. If necessary add additional insulation at floor level by adding additional joists perpendicular to existing and insulate between, board over the top if you want to use the space for storing the Xmas decs/porn collection. Thousands of threads covering this in the Floors section of the Forum.

 

[tomtomgo]

Thanks for the info. I just wanted the loft to be a bit warmer when used for my model railway as being the digital age porn is widely available on the Internet for free

The floor is sufficiently insulated and I have no problems with damp so it was just for warmth.

Cheers,

Tom