Use your imagination…we started with a 9′ x 9′ platform that was not even connected to the tree. We were afraid of killing it if we attached nails and screws to it and it would continue to grow causing the tree house to move. Each year we added to this. The railing around the top… the stairs…eventually, it will be screened in. The mosquitoes are vicious in Idaho! Most of the tree house was built with salvaged materials!