Can a contractor be held liable for something done under his / her initiative?

In general, as long as the contractor constructs the work in the manner indicated by the plans that were drawn up, the contractor is highly unlikely to be held legally accountable for the result. However, should there be insufficient detail to construct a particular work then the onus is on the contractor to request this information from the architect. Should they fail to do so, it is possible that the contractor could be held liable under these circumstances.