While I agree with silentsong, you should also check your availability of resources, although that’s usually more of an RC problem with wood. Having no wood to build the next scaffold will cause your workers to stop.
On the other hand, at which point should they be smart enough to leave a smaller part of the building unbuilt? Instead of the whole roof, only the conflicting part, for instance?
silentsong you were right. I had more then enough resources but once i cleared off that overhang that was above the roof the workers went right back to work and finished the house. I didn’t realize the over hang was their covering the roof blocking the workers from their job. Thanks for all the help everybody.