We have seen a house extension where the new bricks were not cut into the existing wall and there is a straight vertical line of mortar at the junction between the new/old wall. The vertical junction was hidden behind a drainpipe. Has this been done on the cheap? The explanation from the owner was that this was an alternative technique (and that the extension was built on a steel sheet) so that the extension is solid. We're looking to buy the house but are worried that this is dodgy....are we right?