max compressive load on telegraph poles.

Frere Jacques

Hi all,

Building a tree house for the smallies and have been offered some old 10" diameter telegraph poles as a prop to raise the house up. Plan is to take 4 of 7' long poles, cement the last 18" into the ground and then build my 6' x 7.5' floor on this using 4x4s and joists.
Here's the "how long is a piece of string? question".
I'm trying to get an idea of the max load 4 posts can take. They are fairly old, soft in the center (80% sound) but apart from that they are in pretty good nick. I've checked buckling calculators but they are US based so I don't know if they are even comparing similar wood but I'd assume all utility poles are soft wood and would have a similar Youngs Modulus.
Those calculators seem to tell me each pole can take about 4 ton compressive strenght!!! All well and good I suppose till you introduce knots and wind shear etc.
At the moment my plan is to build it (assuming 300kg weight in the rain) and invite 5 of the buddies around for a drink, (another 500kg for the 6 of us) and we can all do a rough approximation of river dance to give it a good test run.
Can anyone give me any tips on a safe working load, assuming a BIG safety factor since it's my kids will be playing in and under it (just not during the riverdance test), or else any other suggestions on the build.
TIA.

Poor Uncle Tom

Please, read the forum charter.