How to make this airtight?

[WWilts]

New build in progress.

 

Roof window (Velux) installed with insulation sleeve around & under the flashing.

 

Problem: Rough opening bigger than the window. Gap between window and rough opening allows free air flow.

 

How to make this airtight? And well insulated?

[MikeSharp01]

Not sure about Velux but we have have Fakro and their insulation detailing on the quad units us great look at their website.might give you.some ideas. Air tightness involves sealing the window frame to the air tight layer - is that your plasterboard or have you got a plastic membrane in there somewhere?

[WWilts]

 

1 hour ago, MikeSharp01 said:

sealing the window frame to the air tight layer - is that your plasterboard or have you got a plastic membrane in there somewhe

Sadly no plastic membrane, only plasterboard with scrim and skim. But might be able to seal an airtight membrane to window frame & plasterboard

[Russell griffiths]

ILLBRUCK air tight foam. 
then pack out reveals with insulated plasterboard. 

[WWilts]

On 13/07/2022 at 08:04, Russell griffiths said:

ILLBRUCK air tight foam. 
then pack out reveals with insulated plasterboard. 

Used Contega solido tape to seal Velux frame to surround. With any luck, that will keep it airtight
Then insulated plasterboard to pack out reveals.