Rafter straps- inside or outside??

[Crofter]

I want to tie my rafters down onto the frame using twist straps (already purchased).

There are three places that I can put them:

- on the inside of the frame, running down the studs. They would then have a sheet of 50mm PIR   placed over them, followed by the VCL and then battens which create the service void. So the batten fixings would hit the metal straps and prevent them from being adequately fixed through to the studs.

- on  the outside of the frame, fixed through the sheathing and onto the studs, either above or below the breather membrane. The first layer of battens then need to be fixed over the top, so again I have the issue of fixings clashing with the metal strap- although at least this time I'm not also working blind through 50mm of PIR.

- on the outside of the frame, but on top of the battens. This minimises the clashing of fixings and metalwork (although the counterbattens will need to be able to run over the top)- but is presumably the least strong out of all the options, and would need longer fixings to reach through te batten, sheathing, and into the stud.

 

Any thoughts would be much appreciated!

[Oz07]

option 2.

[Tennentslager]

Option 2 for me.

Your studs are 47mm right?

Twist straps maybe 30mm?

Slide to one side and nail in at a slight angle. 

That'll leave you room to get a fixing through the batten.

Don't worry about the 5mm thickness of the strap, you'll not notice this once the cladding is on...