Got a job coming up which is a 5/6 year old barn conversion which has shrinkage cracks everywhere. The oak beams that run through the ceiling, some of which are about 20 feet long and a foot square, have big gaps around them where they meet the plasterboard ceiling/walls. Some of the gaps are about an inch wide and quite deep. What is best to use to fill these gaps? I don't really want to use expanding foam as it's messy stuff and I just don't like it. Caulk will just shrink and I'm not so sure that filler will stay put?? Any idea's?