I'm currently in the process of designing a watch tower and was wondering if i can replace my cross braces in my current design with simple knee braces.

Cross brace: enter image description here Knee brace: enter image description here This saves some space and looks a bit better imho. But would it give the same strength as cross braces?

Note that both braces have mortise and tenon connections.

The overal structure is about 4 meters high and 2 by 2 meter width.

Thanks for the idea's!

1 Answer 1


Yes, if...

  1. The means by which you fasten the ends of the knee braces to your structure is adequate. It must be very rigid so no slipping or flexing can occur. There will be substantial shear and tension forces at play. Your mortises should fit snugly.

  2. The posts in your structure are rigid enough. They'll carry a significant amount of bending force due to the longer torque arm that the shorter braces create. Just how much depends on the ratios of braced to unbraced length you go with. I probably wouldn't do less than 1:3.

  • Cheers @isherwood for your words. I'm currently not yet fully capable of making very "snug" wood connections for my braces. So it might be a good idea to keep the crosses in. Although i did do a bit of thinking and i would suspect i need both, the knees to keep the first floor up (otherwise only wood joints would keep the first floor up) and the crosses for main stability. Commented Apr 23, 2017 at 8:58
  • I seriously doubt you need both. Something has gone very wrong if you do.
    – isherwood
    Commented Apr 23, 2017 at 13:53

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