Insulating wide valley

[bsr]

Hello

See the attached picture. I have a wide lead valley (blue) running the width of my house where two pitched roofs join. The valley is about 400mm wide.

I have insulated the rest of the roof space with 300mm mineral wool. What should I do here? Can I fill with mineral wool up to the plywood deck (red), or do I need to leave a space for ventilation? Should I use an alternative product? Normally I would leave spaces at the eaves to allow cross-ventilation, but there is none here since there is a pitched roof on both sides.

Thanks


bsr

 

[bsr]

Anyone?

 

[noseall]

Can't see the point insulating there. You need it closer to the inside of the room.

 

[datarebal]

Condensation is likely to form n the under side of the lead. Slip some pir board under with no gaps

 

[bsr]

Noseall, I'm not sure what you mean. The valley is very close to the rooms. At the moment I have only plasterboard, 300mm air space and then the valley. That's why I want to insulate it, but without causing any damp problems.

 

[noseall]

Noseall, I'm not sure what you mean

The insulation needs to be directly beneath the plasterboard.