Hi Lennart,
I am pleased to see that I am not the only person who is building using scissors braced roofs.
I will take a guess that you are trying to follow a typical north American design where principal rafters are jointed directly to the top of a main post.
The feet of traditional scissors braced roof couples (rafters, scissors, collars, etc.) tend to sit directly on the wall plate and the couple can be positioned and fair faced with a main post or tie beam if a flush wall frame is required or centred if the roof is to be left open.
The recent Timber Framing magazine (no soixante neuf) contains a bumper 14 page scissors brace roof feature.
If you check out the "Design" section on my website you will see a perspective view of a scissors braced roof under the "2 bay Weekend cabin" illustration.
I hope that this helps to solve your problem.
Regards
Ken Hume
Visit
http://kfhume.freeserve.co.uk
