at least 600 mm (24 in.) on each side of the notch or hole. Also use reinforcing when notched partition studs have less than 40 mm (19⁄16 in.) of solid wood remaining. Notching and Drilling of Top Plates In load-bearing walls, top plates must be reinforced with 38 mm (2 in. nominal) lumber when the solid wood remaining in the plates is less than 50 mm (2 in.) in width. If required reinforcing must be placed on the face of the plate or stud, sheet metal may be used to support the wall finish and to protect the plumbing and electrical wiring from gypsum board fasteners. Roof Trusses Roof trusses cannot be notched or drilled. FRAMING FOR PLUMBING SYSTEMS The installation of the plumbing system usually begins after the framing is complete. The initial work is called “roughing-in” and includes installing plumbing vents and drains and all hot and cold water piping that will be enclosed in the walls and ceilings and under the basement floor. Since the bathtub must be installed before the wall finish can be applied, bathtub installation is usually included in roughing-in. 151 Kitchen and bathroom in proximity for minimum pipe length kitchen sink and laundry tub drainage connected to combined soil and vent stack bathtub toilet soil stack cleanout washbasin or vanity use 140 mm (6 in.) stud wall when soil stack continues to upper floors cleanout floor drain in front of laundry tubs in basement waste disposal piping system buried under concrete slab and directed outside the building to the sanitary sewer cleanout exterior face of building