Electricians and carpenters are not the only ones to ch--- Er ah ah hem, make mistooks. In the thirty some od years i was a mason contractor, I ran into many such short cuts. One fireplace/chimney I lost out on, and another i had not bid on, but i was in the Voluteer Fire Department when called to fire at both houses. The masons who built (both had left town long before the discoveries) had sort of forgotten to put flue liners into the chimneys. Many old houses (from before 20th century)were constructed with linerless chimneys, but with great care to the brick work. These two chimneys not only had no liners, but there were joints in the brick/block work with no mortar. I ended up rebuilding one of those chimneys, but would not do any rebuilding until the entire chimney had been torn down and holes drilled into the footings to be sure there had been no skimping in that part. I started bidding on another huge 3 foreplace chimney. There were some suspicious things with the house foundation i did not like so i started measuring the foundation walls. i found the walls were doubled up because the mason had put the first pours in the wrong place. I would not do the estimate until exploration drilling would be performed to be sure the chimney footing was in the right place. The floor slab had already been poured, so drilling was the only way to determine The builder would not do the exploration and i walked away. I understand there were problems with floor cracking a year or so after the house had been sold. I stayed out of that one, but I m sure there had to be problems higher up. By that time, i had moved to a neighboring town and was out of the gossip loops. There are so many ways for the uninhibited to cut corners, even with inspectors supposedly doing their jobs. The dishonest can find ways.
Tinker