Richard replaced a cast iron toilet flange and spacers to stop a leaking problem this past weekend.
He used small wood blocks to build up the sub-floor and a replacement PVC flange with an adjustable gasket to seal on the inside of the old cast iron pipe.
Why did he not anchor the replacement flange to the floor?
All the stresses on the flange are transmitted to the gasket. If the flange were anchored to the floor the movement of the toilet bowl would not affect the gasket.