Roofspace Apartment Insulation Advice

[DIYChrisC]

Hi
I have an apartment on the top floor (partly in the roof) of an old building (1850). I want to add some insulation. I've attached a drawing to explain what I'm trying to do. I've tried to allow a space for ventilation as I've read about doing, but the walls protrude into the rafters so there isn't a flow from the eaves ? I can't find any information that matches my specific scenario. Can anyone offer any advice ? Thank You

 

[Ian H]

If you can stand to loose the room the 50mm insulation would be better as a continuous layer on the undersides of the rafters. That way you also don’t alter any air space between the rafters too.

 

[DIYChrisC]

I think what you've said makes sense to me now too. Thank you for the advice.