Early in the planning process, consider where extra wall depth may be needed to accommodate items that are recessed into walls, such as medicine cabinets and plumbing and/or electrical components that accompany bathroom fixtures. A 6-inch – (152 mm) deep wall is typically needed for these items. Installation instructions for some equipment, like full-body spray showers and wall – mounted/hung toilets, specify a 2 inch by 6 inch (51 mm by 152 mm) studded wall to enclose valves and pipes.
Wall insulation can be beneficial in the bathroom for a number of reasons. The first is auditory privacy. This means privacy for the bathroom user as well as the occupants of adjoining rooms. You will find a complete description of specific noise issues related to the bathroom and how they can be handled in the "Noise" section beginning on page 61. Insulation is also essential when it comes to controlling energy and moisture. Added insulation on the exterior walls will keep the room warmer in the winter and cooler in the summer. A warmer room is more comfortable for users, especially when they are wet, and you will need less energy for additional heating. Added insulation on the exterior also means a warmer wall. Because warm, moist air is attracted to cold surfaces, a warmer wall will attract less moisture and therefore mean fewer condensation problems. Moisture control is covered in more detail in chapter 3, "Environmental and Sustainability Considerations."
If you want to add additional insulation but do not plan to replace the wallboard on bathroom walls, you will probably need to use a foam or blown-in type insulation to fill the walls. Professional installers can do this for you. If the wallboard is being replaced or you are working with new construction, consider adding insulation in all walls that adjoin another room and extra insulation on exterior walls.
Excess moisture is another issue associated with bathrooms. Because of all the moisture-producing activities, special measures must be taken when constructing the walls to prevent mold, mildew, and rot from forming. The shower, steam room, and tub all produce moisture that can come into contact with the walls. To prevent this moisture from making contact with the wall structure, cover all walls in these heavy moisture areas with water-impervious wallboard. If you have a steam shower, the ceiling must also be waterproof, as well as sloped or curved to allow water to drain off. Refer to chapter 3, "Environmental and Sustainability Considerations" for more information on moisture control and ventilation.