Our loft joists have bowed as has the ceiling underneath. Who do we contract to do the necessary work? A guy from a roofing company came and said joists weren´t really what they do, it was just the roof itself. I´m looking at general builders on Checkatrade ( the carpenter listings don´t mention joists) and there´s no way of knowing if these general builders have experience of working with loft joists and know how they should tie in with the existing roof.