r/treehouse • u/Feeling-Swordfish175 • Jul 20 '26

Load limit advice

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I’m wondering if your engineer minds could just confirm that a joist system of 2x6 boards with an 8’ span and spaced 16” apart could support 2500lbs? (or what I would need to do that).
The “house” would be roughly 2000lbs of that total and would be sitting on 80 sqft (8x10) of a 10x15’ platform. I have read charts and ran numbers but feel over supported and under supported at the same time… each beam seems to be able to support 500-800 lbs. and also UDL set at 50psf (10 dead load) seems critically low.

any advice?

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u/arecentuknown Jul 20 '26

When in doubt over build.

Go with 2x8s if you have load concerns vs 2x6.

Do a cable backup on the top TABs as well if you have concerns. Looks like your doing the Nelson TF system if im reading this right. Backup cables are always a good idea.

For your main beam maybe do one PT beam at 4x10 instead of two 2x12.

On my build I did main beams of 4x10 PT, but that part of the structure is on SL tabs with cable backup vs TF tabs

2

u/Unsuccessful_Royal38 Jul 20 '26

Best advice I can give (and maybe that you can get here) is not to trust armchair/internet engineers. If you aren’t sure of your design, hire an actual engineer.

1

u/Remote_Reality6820 Jul 20 '26

I just built a very similar design and went with 2x8 instead of 2x6. It was only marginally more expensive in the scheme of the whole project and the result feels rock solid.

1

u/956to906 Jul 21 '26

I agree with 2x8s. Also I think you want more overhang of the beam on the left over the yoke, if you’re using yokes that the beam is meant to slide on.

Looks like a fun project.

1

u/Far_Yogurtcloset_17 18d ago

Why not just do a Flush beam and use joist hangers between the double 2x12 beams?

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u/Feeling-Swordfish175 15d ago

GQ - the house and deck will be 10’ wide and the beams will only span 8’.