In Toronto, the real estate market has been HOT. With homes being sold at record prices, banks are doing more appraisals to protect themselves. You might have offered to purchase a home for $1 million dollars but that home is really worth $900,000. Banks would have a lot to lose if you default in payments. The lenders want to make sure that the money being lend to you is protected and appraisals are usually the way to do it.
Lenders would send in an appraiser after an offer to purchase has been accepted, but before the mortgage is advanced and the Buyer takes possession. The appraiser will physically go to the house and compare it to recent sales in the surrounding neighbourhood.
There are situations when the appraiser does not think the home is worth what the buyer and seller agreed what it was worth. In this situation, the buyer would have 2 options:
Find another lender who sends in another appraiser.