I'm planning a build of a back yard jungle gym/mini ninja warrior obstacle course and I'm in a bit of a pickle.
On the one hand, I don't mind spending more for cedar and I prefer the look, however, the availability of dimensional cedar is quite limited. Whereas PT lumber is easily available in multiple sizes.
One key consideration is whether an 8ft span of 2×6 cedar will hold up to being used as the side rails of a monkey bar since that is the largest board Home Depot and my local lumber yard carries. I expect kids and adults to be using this structure.
I've reviewed span calculators, but I'm not sure if it's applicable to a point load like this where, for example, 200lbs could be hanging on two beams at a single point in the center. I'm also not sure if 2×6 cedar is hard/strong enough for this purpose.
In another area of the structure, I will be hanging boards across it like this:
Will an 8ft 2×6 cedar board be sufficient to support an adult?
Best Answer
For one Western Red Cedar 2x6 plank, loaded vertically, attached to bombproof supports at either end:
The estimated sag is about a quarter inch in the center, and the shear is 1.39 MpA. Materials data gives me an approximate Shear strength of 5.5 MpA, so you're well within limits.
HOWEVER, the weak point will be the attachments. These will need to be rigid in shear and in bending.
As well, you'll need to design the beams each plank is attached to to support the full load.
8 feet is an invitation to overloading.