You need a toilet flange extender when you add new flooring to your bathroom. Ceramic tile and laminate flooring will add a half an inch or more to the height of your floor. This will leave the toilet flange in a depression below the line of the floor.
For related topics you want to see the articles 'Repairing a Toilet Flange' and 'Troubleshooting Toilet Problems' for more information.
If you replace the toilet without building up the toilet flange you could be faced with a leaking toilet base. This type of leak means dirty water on your floor.
Another scenario you might have is a toilet that is leaking at the base. When you try to repair it you find that the flange is too low for the height of the current flooring.
Using a toilet flange extender once the toilet is removed is not hard and does not cost very much. It is better to do the job right at this point and not have problems later.
Purchasing a Toilet Flange Extender
You can find toilet flange extenders online, at a hardware store or a home supply store. They can range in price from $5 to $20. The more expensive ones have multiple inserts to adjust the height more precisely.
Most types allow you to leave your old wax ring in place. The new one will install over top of the old one.
Installing a Toilet Flange Extender
You are going to want to follow the instructions for the particular part that you purchased. If you have the option of adding inserts, you will want to do a dry fit to see what works best for you flooring situation.
The extension rings for your tolet flange should screw into your sub floor with long plated wood screws. The new ring will form a bond with the old one.
At this point you are going to want to install new toilet flange bolts or tee bolts as they are sometimes called. You want to double nut them so you will not have trouble loosening or tightening them in the future. See the article 'Replacing Toilet Flange Bolts' for more information on this subject.