Dry lining rooflight upstand - condensation risk ?

[bmj1]

Hi all,

 

We've got some rooflights built like this:

 

 

I'm not entirely sure on the insulation in the upstand (if any).

 

Is there any reason not to use a insulated plasterboard here (17mm PIR + 9.5mm plasterboard), in order to reduce the thermal bridging ?

 

(My concern is of creating interstitial condensation)

[Nickfromwales]

I always recommend Marmox boards and plaster directly to them.  

[Dave Jones]

upstands should have the same level of insulation as the roof. 99.9% of chippies totally ignorant of this fact including yours. 

[Wumpus]

We used compacfoam to form the upstand. Robust and insulated.

[nod]

99% are boarded withe 12.5 mil wallboard without any condensation issues Ideally there would be enough room for an insulation board But there rarely is 

[Dave Jones]

3 hours ago, nod said:

99% are boarded withe 12.5 mil wallboard without any condensation issues Ideally there would be enough room for an insulation board But there rarely is 

make the upstand wider externally. still takes the same size light and has full level of insulation.

[bmj1]

40 minutes ago, Dave Jones said:

make the upstand wider externally. still takes the same size light and has full level of insulation.

 

I've got space for insulated plasterboard internally, just wondering if a risk of condensation?

[Dave Jones]

15 hours ago, bmj1 said:

 

I've got space for insulated plasterboard internally, just wondering if a risk of condensation?

 

as long as the U value and depth are the same as the roof. e.g lower U value (more ££££) can be slimmer as long as end result is same.

[Nickfromwales]

25mm Marmox + skim. Almost 100% of the thickness is then insulation.