Hopefully he also told you what YOU need to do (or not do) to keep your new room in good condition. Here is a list of the most common maintenance DOs and DO NOTs after a bathroom renovation:
DO... Make sure natural stone is sealed. This includes granite, marble, slate or any other porous natural product and may include tile, counter top or tub/shower surround materials. Follow manufacturer's instructions regarding the type of sealant and how often it is applied. Stone surfaces should be re-sealed every few months to few years depending on the type, location and traffic.
DO... Seal all grout lines. Tile grout is also porous and needs to be sealed regularly. Again, refer to the manufacturer's instructions for the type of sealer required and frequency of re-sealing.
DO... Check for cracks in grout and repair as necessary. Settling in the building and general use may cause small cracks to form in grout over time or, in some cases, even chipping. Any grout that has "failed" should be fixed as quickly as possible. This is particularly important in wet areas like the shower, bath tub surround and floor.
DO... Check all caulking and repair/replace as required. Caulking provides an important moisture barrier in many areas of the bathroom. Key areas include the joint between the bath tub or shower base and wall tile, the corners of tiled walls, around shower/tub fixtures, between the counter top and backsplash, around the windows and others. If you plan to perform this fix yourself, ensure you use a silicone based caulking and carefully follow the manufacturer's instructions.
DO... Routinely check under sinks and behind toilets for evidence of water leaks. This is particularly important if the water supply and waste lines were not replaced as part of the renovation. Some leaks can be fixed by a handy homeowner and others should be looked at by a licenced plumber. Speak with your contractor if you are unsure.
DO... Turn on the bathroom fan before running a bath or shower. And leave it running a minimum of 20 to 30 minutes after you are done. This will reduce the potential for mold growth.
DO NOT... Screw anything to a shower wall, bath tub surround or floor. Piercing the waterproof membrane behind tile (particularly in a shower stall) can create a pathway for water to travel into walls and floors creating rot, mold and, in severe cases, structural damage. If you need to permanently attach anything to bathroom tile, speak to your contractor.
DO NOT... Over tighten toilet bolts. A new toilet may become loose or "wobbly" over time as it settles on the wax ring. If you plan to re-tighten the bolts yourself, be careful. Applying too much force will form cracks in the porcelain that can cause water leaks or even a pathway for dangerous sewer gasses to enter the room.
DO NOT... Use the wrong cleaning products. Care should be taken to use the cleaners approved for each surface. For example, some common household chemicals will stain natural stone or cause sealer deterioration.
DO NOT... Use a regular interior paint in a bathroom. Kitchen and Bath paints are formulated to be moisture resistant and will last longer than regular paints when subjected to steam.
DO NOT... Take ceramic mugs into the bathroom. Or at least be very careful. With enough force, your dropped coffee mug can cause chips or cracks in ceramic tile (or even glass.) Pieces of a broken ceramic mug (or chipped tile) are also as sharp as glass and can result in severe cuts.
Your contractor may have other recommendations based on your bathroom design and specific materials. Keeping up with the maintenance will add years to the life and looks of your new room!