After what feels like months, the forecast is for 2 days without rain or strong winds, so, at last, the waterproof EPDM membrane for the “flat” roof system can go on.
Over the (checked for nail heads etc.) marine ply sheets is a protective layer (white below) and then the thick rubber EPDM (ethylene propylene diene monomer) rubber sheet.
The MVHR is due to start being installed tomorrow, so some of it’s ducting has arrived: