Roof Collars

[Vonnell]

I'm involved with a loft being boarded for storage. 7x2 purlins are braced centrally by 4x3 struts. Two 6x2 collars then span the roof at thirds. The guy wants the collars removed as they do make access difficult.
I've advised him to sister the binders below the purlins and fix a 4x3 hanger from binder to purlin where the collars were. Then fix new collars above head height from rafter to rafter. Does this sound right?
If so, how many new collars are needed and would he use something like 4x1 or 90CLS? I told him he could borrow my nail gun to fix the collars

 

[^woody^]

The collars are bracing the purlins/rafters at mid span. If you remove the collars, I can't see how the doubled up binders and hangers will compensate for this bracing - its a solution to a different problem. Same with putting the collars higher up.

You may just as well remove the collars only and not bother with the other work. But advise the guy he does this at his own risk and the possibility of gradual deflection of the rafters is increased

In these situations, what you should do is install bracing to the posts/binders/purlins from the eaves. But the ceiling joists must the adequately bracing the roof for this solution to be effective

CLS is not structural timber unless graded as such - and you really want to use treated timber in roof construction

 

[Vonnell]

Ok, will take that on board. Cheers Woody