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 Triebwerk mechanism. Bürde thing is i wish there welches an auto stop at the bottom. i can Tümpel my wife https://attic-lift09752.yomoblog.com/42097849/the-greatest-guide-to-attic-lift