Finishing breathable membrane around door and windows

[joeirish]

So I've been building a garden office and need some advice on how to finish the breathable membrane around door and windows. I've now seen e different methods. An X cut out with the membrane then folded into the building on all four sides of the opening. An 'I' cut out with just the sides folded in and the flush edges taped at the top and bottom. And thirdly a flush cut out with the bottom edges under the fill taped and sealed then the other edges taped directly onto the window frame after it is securely attached. This last one to avoid dampness creeping into the inside under the membrane. Would appreciate views on which is the best method. Thanks.

[molynoox]

I think I would be more focussed on the bottom edge / cill if you had to chose where to achieve maximum sealing performance, which rules out the 'I' shape in my view. I personally did the X cut in the membrane and then used Dupont flexwrap all around the frame as well. But I think this was probably overkill

Martin

Edited December 12, 2021 by molynoox
typo

[Dave Jones]

be mindfull on the top and sides that by bringing the membrane inside you are giving moisture a track to get it via gravity.

[Thorfun]

8 hours ago, Dave Jones said:

be mindfull on the top and sides that by bringing the membrane inside you are giving moisture a track to get it via gravity.

this is a pertinent subject for me as our windows are going in next week and I was going to ensure the breathable membrane was correct this week. Are you saying that the breathable membrane should stop before the windows rather than carry it on past the windows?