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Currently, the collar ties in the garage (from 1950) overlap the rafters and are nailed into the rafters from the side with just two or three nails on each end. There is one collar tie every 4 feet (1.22 m).

This might be sufficient, but I would like to increase the strength for roof loading. Below is a picture showing one end of the collar tie.

Questions:

  • Are there straps that are designed for connecting an angled rafter to a horizontal collar tie?
  • If so, what type of strap and what shape should it be to effectively connect the collar tie to the rafters?
  • Other considerations or best practices?

collar tie

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    FYI, these are rafter ties, as they're on the wall plate. Collar ties are higher, intended to increase headroom (or add stability if used in conjunction with rafter ties).
    – isherwood
    Commented Feb 22, 2023 at 14:27

2 Answers 2

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Brackets and straps aren't always the answer. Here they're simply not needed. Just add a few screws.

I owned a very similar garage, circa 1958. It experienced many heavy snow years in its lifetime and didn't show any sign of problems despite having only two rafter ties. You have twice that many, so the concern is halved. A few 2-1/2" construction screws (piloted to prevent cracks) tightened things up nicely and added more shear strength. That's all that's needed. Pilot full-diameter through the first member to allow slip, and roughly half into the second.

Brackets must be rigidly fastened or they don't prevent sag due to positional shift. They may prevent catastrophic failure, but you want more than that. You want a positive position lock. Unless you find a bracket that's exactly suited to your situation and install it very well, it's just an unnecessary expense that doesn't accomplish much.

If you insist, avoid bends, which can flex. Any long, flat strap of heavy gauge steel will do. It needs to be long enough that the effect of the 1½" offset is diminished. Something in the range of 18-24" would be fine. Fasten it to the face of the assembly showing the full rafter tie with 4-6 screws at each end.

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Check out the SIMPSON STRONG TIE catalog.

There are connectors for most any construction situation. However if you are looking to increase the load bearing capacity of the roof rafters, you should look into adding gussets. These can be plywood added at the corners.

Advice pertaining to your specific needs should come from an engineer.

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  • Gussets are fine, but they're require blocking out one member. This essentially shifts the problem without buttoning it up, since the blocks will only be held by shear fasteners just as the rafter ties are now. I suppose if the gusset was installed between the members....
    – isherwood
    Commented Feb 22, 2023 at 14:22
  • Actually I did look through different Simpson ties, but wasn't sure what to use. Do you have a suggestion for that scenario? Basically we would need a tie that can link two overlapping 2x6's at an arbitrary angle. (Even "hurricane clips" turned 90-degrees might work if we screw one into the top of the rafter-tie and the other into the side of the rafter because they are intended to prevent a lifting force, but wasn't sure if there was a Simpson strap intended for this specific purpose.)
    – KJ7LNW
    Commented Feb 23, 2023 at 0:02

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