UPVC double glazed window in shed.

[Howie1000]

Good morning all, I think I posted this in the wrong section earlier.

I’m part way through building my workshop/shed. It’s framed with 4x2, has cellotex insulation, 11mm OSB inside and out, then will be externally clad with featheredge.
I have a 3ftx4ft UPVC double glazed window and UPVC double glazed french doors to install, I’m not 100% sure of how to do it. I’m going to build the wood frame work for the door and window with a 5mm gap, but it’s the water proofing part that is stumping me. The window has a sill attached already.
Many thanks !
David.

 

[MikeG.]

All windows rely on a mastic bead for water-tightness. It is entirely up to you where you design this bead to be. Personally, with boarded walls I build a 2x1 or 3x1 frame around 3 sides of the window (sides & top), slightly overlapping the frame, and silicon the junction. This means that if the window ever needs replacing all I have to do is remove the 3 pieces of wood, fit the new window, and replace them. Remember, all timber cladding is designed on the assumption that water will penetrate: you have to allow it to get out again, and for the timbers to dry off with good air circulation behind.

 

[Howie1000]

That’s great, Thank you very much for the reply.