Where to cut 2 rafters for skylight

[gasbusters]

Hello guys, im doing my loft skylight and just realised the rafters are too close for me to get away with cutting one to fit skylight.

The skylight is 78 x 98cm velux centre pivot. The gap between the two rafters is 76cm.

So it looks like il have to cut two rafters, which im guessing will considerably weaken the roof?

Can someone advise qhats tje best way of strenghtening the opening?

I was going to double up the two joists on either end of the window that have not been cut using 2x6 beams.

Then double up where the rafters have been cut top and bottom using 2 x 6 beams.

In the photos I have made a 78x98 template to show where the window will fit

Any advice would be much appreciated

 

[gasbusters]

 

[noseall]

Everyone will be wondering why you don't move it to left 8" so that you only need remove one rafter.

Anyhoo, seeing as your Velux is betwixt two purlins, then doubling up the rafters (between purlins) will be ok.

 

[gasbusters]

Everyone will be wondering why you don't move it to left 8" so that you only need remove one rafter.

Anyhoo, seeing as your Velux is betwixt two purlins, then doubling up the rafters (between purlins) will be ok.

The gap on the left between rafters is the one thats 76cm, about 3 cm too narrow to fit the window into.

I was tempted to plane down that rafter buy 3 cm but just enough for the wi dow length then double it up.but not sure its a goid idea

 

[catlad]

Sister a rafter to the one on the left of your mock up frame and start from there. You are supposed to leave a baton width all around your frame. Also if you have some scrap timber screw it across the rafters above your frame, helps to keep the rafters in place when you cut through them.
not necessary at the bottom because the purlin will do that.

 

[noseall]

not necessary at the bottom because the purlin will do that.

..or at the top (second image).