an extention is being built on the side of my house, it is currently up to just under first floor height. There are no holes knocked throughthe exterior wall yet only cut for the vertical damp proof course. However there are small cracks starting to appear in the existing house where the ceiling joins the walls which were not there berore the extension starting, do you think it is just settlement caused by the weight of the new walls hanging on the old or movement caused by cutting with the sthil saw or a combination of both. any thoughts apprieciated please.