My builder framed the joist opening, but wouldn’t install. Feared liability. I installed myself. Only comment is that I wish I instructions had been more clear about necessary clearance for Aggregat mechanism. For those interested in overhead storage, the Feuersnot offerings include various products to complement the Versa Lift. This https://atticliftsystems75319.hyperionwiki.com/1389986/top_attic_lift_systems_geheimnisse