How many porta potties per person does OSHA require, and does the rule change by trade?

OSHA 29 CFR 1926.51(c) requires one toilet seat and one urinal per 40 workers for a construction crew of 20 to 199 people. For your framing crew of 28, that means one standard portable toilet and one portable urinal meet the minimum. When you grow to 45 workers, you still need one toilet seat and one urinal per 40, so one standard unit and one urinal remain sufficient. Urinals count toward the OSHA requirement because the rule specifies "toilet seat and urinal." The rule does not change by trade; it applies to all construction work under OSHA jurisdiction.

Service and placement
A long-term rental with weekly service is standard. The service visit includes pumping the holding tank, adding deodorizer, restocking toilet paper and cleaning the interior. Place the units on level ground within 25 feet of where the vacuum truck can park. Blocked access results in a missed service and a billed trip.

Adding units for comfort
OSHA sets minimums, but crews appreciate more units. For 45 workers, consider two standard portable toilets or one deluxe unit with a flushing bowl and sink. Add an ADA-compliant unit if anyone needs wheelchair access. High-rise units are available for upper floors, lifted by crane.

Vandalism and winter
Locking units reduce vandalism. In freezing weather, operators add antifreeze to the holding tank to prevent ice. Flushing units and handwash stations may freeze and are often swapped out.
Ask if you have specific questions about your site setup.

OSHA 1926.51(c) applies to all construction trades, but mobile crews with transportation readily available to nearby toilet facilities are exempt. The rule counts urinals toward the requirement, so one standard portable toilet and one portable urinal meet the minimum for 40 workers. For 45 workers, you still need one toilet seat and one urinal per 40, so the same setup works. Weekly service is standard, but heat or heavy use may require more frequent visits. Place units on level ground within 25 feet of truck access to avoid missed service charges. Add an ADA-compliant unit if anyone needs wheelchair access, as the ADA cluster rule requires one per cluster.