Accurate birdsmouth for ashlar stud advice

[JCBolty]

Hello,
I'm doing a loft conversion and the SE has designed an Ashlar stud wall which requires a 4x2 top plate birdsmouth jointed to the existing rafter.

I could really do with some advice on how to cut them regularly and accurately across the full width of the roof.

Naturally the rafters are Victorian and some irregularly shaped, just make things more interesting!

Many thanks in advance!
James

 

[catlad]

you can build your stud wall and then offer it to the rafters and with a saw lying on top of the wall as a guide cut into the rafters, don't cut into them any more than a third.

 

[JCBolty]

Thanks Catlad - simple ideas are the best!

If I slightly over cut a joint or two is it acceptable to pack with something non-compressible, like meta plate?

Thanks again!

 

[catlad]

Lead makes a good packer as you can screw or nail through it.

 

[Nige F]

Good advice from catlad - just a thought from me - is there some type of Simpson Strong Tie that would do the job - seems a bit brutal and awkward cutting out existing rafters which will be variable in position, as you surmised.