OSHA 1926.51: do weekend overtime crews change toilet counts?
Weekend overtime crews do not change the minimum toilet count for a construction site under OSHA 1926.51(c). The rule sets minimums by the maximum number of employees present at any one time, not by shift or day. For 50 workers, you need at least two toilet seats and one urinal, or three toilets without urinals. If you have 20 workers on Saturday, that is fewer than the weekday peak, so the existing units meet the requirement.
Follow the peak count, not the shift. OSHA 1926.51(c) says 20 to 199 workers need one toilet seat and one urinal per 40 workers. Your site has 50 workers on weekdays, so you must provide for 50. The weekend crew of 20 is below that threshold, but you already have the units for 50. You do not remove them for the weekend.
Service frequency stays weekly. A standard portable toilet on a construction site needs a service visit every week for pumping, cleaning and restocking. The weekend crew uses the units, so the service frequency does not change. If the units are full or dirty on Monday, the crew will complain.
Placement and access matter. Make sure the vacuum truck can reach the units every service day, even on weekends if that is your schedule. Blocked access means a missed service and a billing trip.
Stick with your weekday setup. Any questions on your specific site?