This problem has been coming up a lot recently, especially with self builders. The question is in what circumstances can you fully fill the rafter depth with insulation.

Here’s the Advice Note No. 5 on Roof Ventilation and Insulation

It shows the concepts behind the key roof details in order to insulate and (where required) ventilate.

The Advice Note is also in the right side bar widget.

A special thanks to Niall Crosson (Twitter handle: @ecologicalbuild ) at Ecological Building Systems for advice on this.

If anyone thinks different to this, I’d love to hear from you…