Client is looking for the custom glaze…
Will be tricky on the change of pitch/ridge (1 side 10 degrees, 1 side 5 degrees…and not a true 45 degree angle).
We are also looking for direction on the centers and size of rafters required? Sheet length will be 2m.
(I had thought using glulam for rafters and thus getting a cleaner look, which would then be painted to look good).
We’re pretty limited in the type of polycarbonate flashings we can get. You’re probably better going for a metal one (from a roofing company), with a soft edge. Then you’ll be able to form the edge to the various pans and ridges of the Custom Glaze butting up together.
Normally you have purlins every 1500mm max, but since your one will be just over 2m total, you’d put a purlin at the mid point i.e. 1m.
If you’re using glulam wider than 70mm (the width of the ridge on the Custom Glaze), and you put them at 600mm centre to centre, then the sheets will join directly over the rafters, and fasten directly into them.
In which case the mid purlin would just be there to stop flex, and would not need to be substantial. If necessary you can put a screw through the mid pan to stop it flexing up from wind coming underneath.
There is a tolerance with the sheets, and they have been known to be 595mm centre to centre, not 600mm. So I would suggest waiting until the sheets are in stock first, and measuring them, before putting the rafters up.