Best practice for bolting roof timbers

[dobson156]

I'm bolting some roof timbers together, specifically collar ties to rafters.

What is the absolute most belt and brace/foolproof way to do this?

So far I am looking at Stainless M12 Hex head + M12 Square washers + with a dog tooth washer between the timbers.

I also considered coachbolts / Mushroom head bolts; but if I use those then I can't really use the square washers to spread load.

Any advice greatly appreciated.

 

[^woody^]

4" wire nails are holding up hundreds of thousands of collared roofs. 2 per connection

m8 or 10 coach bolts, round washers will do, square and dog tooth washers if you like but not necessary No need for stainless fixings unless the timber is acidic like oak and aesthetics is important.

Don't over think it. The load is not spread on the washers, it's on the bolt, laterally.

 

[Scally-Ho]

Yeah, 4" wires have been used in roofing for as long as I can remember. If you want to go a step further, then annular (ring shank) nails are nigh on impossible to pull out.

 

[dobson156]

The reason for wanting to bolt rather than nail is because this is going onto to an existing roof and I don't really want to disturb the slates and ageing felt by hammering away at the rafters. I feel more comfortable drilling and bolting and taking my time with it that way.

Will be a lot cheaper going with zinc coated m10s so will take that on board.