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On a traditional frame, I would like to install a roof window 118 x 78 Velux® type and so I have to make an opening and cut an intermediate failure of 95 x 200. I thought to make a trimmer with faults 75 x 200 on each side fixed with lag bolt on one of the intermediate breakdowns and anchor of failure on a breeze block wall to reinforce the sawed out fault. The breakdown and the wall are spaced from 1.90m, 0.90m between breakdown, the frame is composed of rafters and battens, the length of the breakdown is 3.50m, what advice can you give me?

I will give you first advice to consult a carpenter to know if your framework can support this type of transformation. Always avoid cutting structural elements and prefer to choose another location for the window. You will have to reinforce the frame by elements in parallel, sawing a farmhouse and indeed create a trimmer, essential element for this kind of installation.
See our sheet on mounting a roof window.

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    • Laying a roof window
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    • Mounting a roof window

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