Design against the building you measured, not the one you imagined

By this stage you have a site whose gates cleared and a budget with a fit-out line. Design is where those two meet, and the discipline is the same as everywhere else in this roadmap: the cheap version of every mistake happens on the plan, the expensive version happens on site at trade prices.

Design against the walkthrough measurements, not the agent's brochure. The numbers that shape a gym floor plan:

• Ceiling height at the lowest obstruction, not the highest point. Ducting, sprinklers and beams set your real clearance, and a rig needs height for pull-ups with a tall member on the bar. Measure under the obstruction.
• The column grid. Columns are the most common reason a floor plan does not work. Mark every column on the plan before you place a single platform, because a column in the middle of the lifting area is a constraint, not a detail.
• The floor plate shape and sightlines. Long and narrow behaves very differently to square. A floor you cannot supervise from reception costs you staff hours forever.
• Where the wet areas already are. Existing changerooms in the right place are worth a lot. In the wrong place they are worth less than nothing, because moving drainage is one of the dearest lines in a fit-out.
• The switchboard location. If your electrical work is significant, the cable run from the board to your equipment is part of the cost.

Zone the floor before you pick equipment

Work in zones, strength, cardio, functional, group, recovery, front of house, and size each zone from your brief, not from what fills the space. Equipment schedules come next stage, and they come out of the layout, not the other way around. A layout built around a specific supplier's catalogue is a layout that supplier designed for you.

Two structural rules that are not judgement calls:

• Anything above ground level, a mezzanine or a first-floor strength area, is a structural engineer's question. Dropped weights are an impact load, not a static one, and a full rig is a concentrated load. In the project our field guide is built on, the fit-out budget carried $110,000 of fabrication for a mezzanine. Case study budgeted figure; the facility never opened. That is the scale of spend that makes the engineer's answer worth having first.
• Air conditioning across the floor plate is a deliberate decision, not a default. Among real trading sites we work with, a roughly 1,800 m² gym running saunas, chilled ice baths and split systems paid around $8,500 a month for power, while a similar-sized site running ducted air through the floor paid around $20,000. Operator experience real monthly bills, our own sites and sites we work with, as at August 2026; your tariff and climate will move these. Decide the HVAC scope on purpose, in the design, with your electrician in the room.

What the fit-out costs

The maintained range is roughly $1,500 to $3,000 per m², with soft costs at 8 to 15% and contingency at 5 to 10% on top. Vendor-published Published rate sources and dates in the cost to open calculator, rates as at 25 July 2026.

Who verifies this stage

A structural engineer for floor loading, mezzanines and anything on a suspended slab. A licensed electrician for the fit-out's maximum demand against the supply you verified at stage 2. Your building certifier for exits, accessibility and fire requirements that the change of use attached. None of this page is engineering advice; it is the list of questions to put to the people whose signature counts.