Hi, I am converting my loft into another bedroom, I was going to get it done by a loft company but work is in short supply and so is the cash...I know I have to inform the local council...my house is a 50s semi detached and the loft has 2 windows built in to the new roof I had done last year..it has only got the 4x2 joists and boarded out for storage/junk ect ect...now what I need to know is what size joists will have to be laid down and can the new joists run parrarel along the existing ones or do they go across them ...also do they have to sit on the existing walls or just fitted to the existing joists