I have supported mine only at the ends for a couple years of regular use, but it was only a few inches off the ground...
When I put it in a permanent spot and start relying on it to hold up roof and snow load I intend to support it at all the stock points and at least one more longitudinally centered point beneath a reinforcing post.
Either one if the container is uncompromised. They are designed to be loaded up to the capacity listed on the end and stacked on ships. When stacked, they only make load bearing contact on the corners where the picking eye is. They do not require additional support between the corners if the container is unmodified.
If you have cut holes in the walls for doors or windows then it needs to be supported between the corners. Where and how much depends on how much has been changed.
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posted 3 days ago
They will be 20' in the air with no center supports, only at the ends. The 45' containers have mounting spots at two locations. Do o have to use the 40' location or 45' location. I have never worked with a 45' container
Do you plan to cut any holes in the container walls? If so, that will drastically affect the support needed, as described by others. The exact support required depends totally on where and how the cuts are made, so nobody can advise you without more details.
If uncut, then you can support them at either 40' or 45' spacing, as mentioned by Caleb.
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