We had a large ground floor extension done 6 years ago across the full back of our 30s semi. The back bedroom upstairs has a bay window and has developed a crack in the plaster at the edge on either side over the years. I don't know if it's just shifting that's to be expected and that 1930s plaster will just blow when you have this sort of major work done, but we want to redecorate the room and rather than plaster over the cracks we think we should get the structure checked, and that it was all done safely.
Who would I get in to check this properly? It will all need replastering but I didn't just want to trust a builder or plasterer to tell me "oh yes, that's quite normal, it just needs fresh plaster".
A general surveyor? A structural engineer? What would they need to do to check it's all safe as on the outside some of the new extension roof may be hiding what brickwork they need to look at.