An open project manager seat doesn't just cost a salary — it costs project margin, schedule, and the burnout of every PM covering the gap.
Direct cost: the salary you're saving. Indirect cost: the margin slippage on projects the missing PM should be running. For a commercial mechanical PM running $15M–$25M of annual revenue at 12–18% target margin, every month of vacancy costs roughly $25K–$45K in margin slip and schedule recovery cost. After 90 days, the math gets dramatically worse because senior PMs covering the gap start declining new pursuits.
Three multipliers: (1) projects assigned to overloaded PMs slip on submittal turnaround, which costs change order recovery; (2) the operations team starts saying no to RFPs because there's nobody to run the work, which costs forward revenue; (3) the senior PMs picking up slack start interviewing because they're carrying two jobs, which costs you a second seat and a retention problem.
For experienced commercial mechanical PMs ($15M+ revenue capability), expect 75–110 days from req open to start date in a competitive metro. That's source, screen, interview cycle, offer, counter-offer dance, two-week notice, and any moving timeline. Internal promotions are faster (30–45 days) but only work when the bench is already deep.
Three levers: (1) run a continuous warm pipeline — a senior recruiter brings 8–12 vetted candidates per quarter even when no req is open, so when a seat opens you start from a shortlist, not from zero; (2) tighten the interview loop to two rounds in two weeks (most contractors stretch this to 6+ weeks and lose candidates); (3) pre-clear offer authority so the hiring manager can move when a candidate says yes.
When the gap is acute (>60 days), the project is mid-stream, and losing schedule will cost more than the contractor premium. Contract PMs run $185–$275/hr loaded in 2026. That's expensive — but a 30-day schedule slip on a $20M healthcare project costs more than 6 months of contract PM fees in liquidated damages alone.
The first 90 days decide year-three retention. Assign a project that's challenging but winnable, pair the new PM with a senior operator who actually mentors (not just signs reports), introduce them to three customers in the first month, and review compensation at six months — not the typical annual cycle. PMs who feel set up to win in year one stay through year five.
Filling the seat with the wrong candidate to stop the bleeding. A bad PM hire costs 18–24 months of cleanup — projects they touched have to be re-baselined, customer relationships have to be repaired, and the team has to recover from the management style. The math says: stay open 30 more days, hire correctly, and net out positive within 9 months.