I am building a stud wall on the top floor of our extension which has a flat roof. The joists run parallel to the direction of the partition so I know I need to add noggins. But I can't get access to the ceiling joists from above because the roof is flat, and getting access would involve chopping into the ashphalt ceiling.
So I'm guessing I need to gain access to the ceiling joists from below. What is the best way to do that? Should I seek to remove entire ceiling boards rather than chop into them?