Framing
A key part of your new tile installation is ensuring your walls are free of any deterioration and sturdy enough to build onto. After completing the demolition process, whether your going to start a full remodel or just a partial freshening up of your bathroom, the walls are exposed and you can begin to see the health of the studs.
Inspection
Your first step is to identify if the wood has been exposed to moisture that leaked in from the shower or from faulty plumbing. If you have chosen to undergo a partial remodel, then your limited to amount of inspection you can complete, but it is still worthwhile. Where a shower pan or bath tub meets with the walls in the shower area, you will immediately see discoloration, wetness, or in extreme cases damage to the wood. The damage can be minimal or it can be complete deterioration in the form of wood rot.
Replace
Finding damaged wood that has been exposed to moisture, whether behind the walls or even in the floor, will need to be replaced. Since the wood framing is the key to the structural stability of your bathroom remodel, ensuring each stud in the wall or running board and floor joist is free of damage is imperative. A professional contractor will be able to remove the damaged wood and replace it with wood that is cut to size and plumb to the wall or level with the floor. Your wood choices are going to be pressure treated or non-presure treated, ideally a pressure treated wood will be resistant to moisture damage under normal conditions. You also have to consider that pressure treated wood is going to dry out and can be prone to twisting, therefore, you will need to determine which is best and within the building code requirements in your area.
Reinforce
In the fortunate event that the wood framing of your bathroom has not been exposed to moisture and free of any damage, during inspection you should have been able to determine if the any reinforcement will be required. In the event that your bathroom remodel includes a built up shower pan, you will be adding a few hundred pounds to the floor and that pressure will be spread to the walls. A professional contractor will be able to determine if the current framing will be able to sustain the weight of new construction, plus the transitional weight from normal usage.
Level Wall Studs
With your wall studs exposed, using a a level or a straight edge, you can determine if you have any wood studs that are extending outward or inward, or even bowing into each other from the weight of your home settling. If you install a tile substrate over mis-leveled wood studs, the result would be a wall that is not straight, and would have to be compensated with a thicker applied tile adhesive. Planning ahead of time, by sistering new wood to existing wall studs or shaving off bumps where needed, will provide you with a straight surface to install your tile substrate, which ultimately will give you a much more problem free installation of your tile.
Construction
With a partial bathroom remodel, you might choose to only replace the tile on the walls. if this is the case, then you may also want to build a custom shower niche into one or multiple walls to store shower accessories during usage. If your looking into a complete bathroom remodel with a built up shower pan, your going to need to construct a shower curb to keep all water from the shower area from entering the rest of the bathroom. Additionally, you may also want to construct a section wall, or shower pony wall, that divides the wet area and non-wet area. As an added convenience during usage, you can construct a shower bench or shower seat inside the shower pan which gives you an extra added comfort. All of these additions can be constructed with wood materials, as a pre-manufactured component, or a combination of both, depending upon your preference.