flat roof insulation

[eon2000]

Can anyone please help. I have a bedroom extension over the garage with a flat roof. I want to insulate the roof but I'm concerned about condensation and mold. I was going to use some rockwall and push it down between the joists from within the house main loft. I think the roof is a cold roof as there is no external ventilation. As the flatroof is joined to the house loft, will the air flow be sufficient enough to not cause condensation.
Thanks[/b]

 

[tony1851]

If it's a flat roof, how can you insulate it through the house loft?

 

[freddiemercurystwin]

Aye a bit or terminology gone astray there me thinks. Maybe a quick sketch would help.

 

[jabuzzard]

If it's a flat roof, how can you insulate it through the house loft?

As the original poster says the flat roof is joined to the main house roof which is presumably pitched. As such there is probably a gap between the main roof and the flat roof into which you could in theory push insulation. My parent's house is like this.

The reality is that you will struggle to push insulation down there. Best option is to pull the ceiling down, insulated with celotex/kingspan and reboard with insulated plasterboard.