Between them (horizontally) run the main beams supporting the roof.
the roof has been insulated with 100mm kingspan leaving a 50mm gap to the felt at the back oif the slates, foilback plasterboarded and plastered.
Problem :- The beam between the topmost and middle velux has a weepy wet water mark that doesn't actually drip off but has not gone away yet (such that we can't varnish that side of the beam or the small 6inch piece of plasterboard that spans between the beam back to the roof.
The beam between the middle and lower velux has no problems whatsoever.
The only difference we can see (without starting to rip it all down) is the lap of the flashings - the problem area has a 2inch lap between the bottom flashing of the top window and the top flashing of the middle window, the other velux has a 6inch lap at this area.
Is this the problem i.e. water penetration ? how would I tell if it were condensation from the inside? Anyone know the minimum lap for veluxes installed above each other? Any suggestions for what to do next?
thanks in advance