Evil hybrid roof construction

[bmj1]

Okay, I think this is very bad, but want to get opinions:

 

• We have a finished flat roof: 100mm warm deck above, and for some reason, 25mm between the joists ?!
• The insulation between doesn't appear to be pressed up tight against the plywood above (which I understand is the thing to do when doing this), but instead, there is a gap due to the piece of wood running across above the joists
• I'm concerned about interstitial condensation

 

Is the only sensible option is to remove the 25mm insulation between, and live with 100mm insulation above... and make up on the SAP elsewhere ?

 

Edited June 21, 2023 by bmj1

[Mr Punter]

I don't think there will be an issue with 25mm.

 

It will help a bit with u value and leave you space for services.  I assume you have VCL on top of the ply?

[ETC]

Ask Unilin (was Xtratherm) to do an interstitial condensation risk analysis for you. They can do it over the phone and email you the results within 30 minutes.