Sequencing a Commercial Building Schedule, Start to Finish

Every commercial building is different, but most of them go up in roughly the same order, and most schedules get the same few things wrong. This post walks through the typical sequence of a mid-rise commercial building with a steel or concrete frame, phase by phase, with the handoffs that drive the logic and the items that tend to sneak onto the critical path. Use it as a checklist when you build a new schedule or review someone else's.

The big picture

At the highest level, a commercial building schedule has a handful of overlapping streams:

1. Preconstruction: permits, submittals, procurement
2. Sitework and foundations
3. Structure
4. Envelope, ending in dry-in
5. Interiors, floor by floor
6. Building systems: permanent power, conditioned air, vertical transportation, life safety
7. Inspections, commissioning, and closeout

Streams 4, 5, and 6 overlap heavily. The art of sequencing a building is mostly about managing those overlaps without creating impossible handoffs.

Phase 1: Preconstruction and procurement

This is where the critical path usually starts, and it is the part most often left out or treated as a single bar.

Long-lead items to schedule explicitly, each with submittal, review, fabrication, and delivery:

• Structural steel (shop drawings and mill orders)
• Electrical switchgear and transformers
• Elevators
• Curtain wall and storefront systems
• Major HVAC equipment: rooftop units, air handlers, chillers, boilers
• Generators
• Specialty items: kitchen equipment, lab casework, anything owner-furnished

A typical procurement chain looks like this:

Submittal prep -> Submittal review -> (Resubmittal, if likely) -> Approved
  -> Release for fabrication -> Fabrication -> Delivery -> Install

The delivery date should drive the install activity. If switchgear arrives in month 14 and permanent power is needed in month 13, the schedule needs to show that, and it is far better to find out at baseline than at month 12. Estimating Activity Durations the Field Will Believe covers how to set realistic review and fabrication durations.

Permits belong here too. Many jobs start on a foundation or early-site permit while the full building permit is still in review. If so, show both, and make the vertical structure depend on the full permit.

Phase 2: Sitework and foundations

Typical sequence:

1. Mobilization, site fencing, erosion control
2. Demolition and clearing, if any
3. Mass excavation, and shoring if needed
4. Underground utilities that conflict with the building footprint
5. Footings and foundation walls, often in pours by area
6. Underslab plumbing and electrical, with inspection
7. Under-slab vapor barrier, then slab on grade

Watch for:

• Under-slab rough-in and its inspection are their own activities. The slab cannot be poured until the inspection passes.
• Slab on grade timing. On a steel building, you can pour the slab before or after steel erection. Pouring first gives you a working surface for lifts and lay-down. Pouring after avoids damage from erection equipment. The choice changes the logic, so decide early.
• Site utilities and the utility company. Permanent water, sewer, gas, and especially electrical service often depend on the utility's schedule, not yours. Get their lead times early.

Phase 3: Structure

For a steel frame:

1. Anchor bolts and base plates set during foundations
2. Steel erection by sequence (often a few floors or bays at a time)
3. Metal deck
4. Shear studs and deck inspection
5. Concrete on metal deck, floor by floor
6. Spray fireproofing, often after deck pours and MEP hangers are installed above

For cast-in-place concrete, the cycle is form, reinforce, embed, inspect, pour, cure, strip, and reshore, floor by floor. The floor cycle time is the heartbeat of the structural schedule.

Topping out is a good physical milestone here. More useful still is linking the start of each floor's envelope and interiors to that floor's structure, not to topping out of the whole building. That is what lets the work stack up behind the frame.

Phase 4: Envelope and dry-in

The envelope typically includes:

• Roofing (often started as soon as roof structure allows, since it is the first step to keeping water out)
• Exterior wall framing and sheathing, air and water barriers
• Curtain wall, storefront, and windows
• Exterior cladding: metal panel, masonry, precast, EIFS
• Exterior doors and temporary closures

Dry-in is the milestone that matters. It is the point at which interior finishes can start without water damage. Be specific about what it includes. See Milestones That Actually Mean Something for how to define it.

On larger buildings, dry-in usually happens floor by floor or zone by zone rather than once for the whole building. If so, model it that way, so Level 2 interiors can start when Level 2 is closed in, not when the whole building is.

Phase 5: Interiors, floor by floor

Interiors are where the schedule repeats itself. A typical floor sequence:

Three relationships worth getting right:

• Rough-in follows framing by area, not by floor. Use a start-to-start relationship with a lag, or split the floor into zones. FS, SS, FF, SF: Choosing the Right Relationship Type covers when each fits.
• Inspections are hard gates. A failed in-wall inspection stops drywall. Give inspections their own activities.
• Finishes that are temperature-sensitive (wood flooring, millwork, some paints and adhesives) should depend on conditioned air, not just dry-in.

Floors typically proceed in a stair-step pattern, each floor a few weeks behind the one below, so crews can roll from floor to floor. If your schedule has every floor starting framing on the same day, it is probably not a plan the trades will follow.

Phase 6: Building systems

These span floors and tend to drive the end of the job:

• Permanent power. Switchgear delivered, installed, terminated, inspected, and energized by the utility. Many downstream activities depend on it: equipment startup, elevator testing on permanent power, fire alarm testing, commissioning.
• Conditioned air. Mechanical equipment set, ductwork and piping complete enough, controls functional, startup. Needed for finishes and for commissioning.
• Elevators. Long lead, then installation in the hoistway (which needs the hoistway built, plumb, and protected), then the state or local inspection. Often used as a construction hoist before final, which has its own logic.
• Fire alarm and life safety. Devices installed, programmed, pretested, then the acceptance test witnessed by the fire marshal. Sprinkler testing, fire pump testing, smoke control testing if required.
• Testing, adjusting, and balancing. After systems are running, before commissioning.

The combination of permanent power, life safety acceptance, and elevator inspection is very often the critical path into TCO.

Phase 7: Inspections, commissioning, and closeout

1. Final inspections by trade (building, electrical, plumbing, mechanical)
2. Fire marshal acceptance
3. Elevator inspection
4. Temporary or full Certificate of Occupancy
5. Commissioning, functional performance testing
6. Punch list: creation, completion, back-check
7. Substantial Completion
8. Owner training, O&M manuals, as-builts, warranties
9. Final Completion

Two things go wrong here constantly. First, the inspection and commissioning activities are given a few days each, when in reality each depends on an outside party with its own calendar. Ask the local authority what their lead time actually is. Second, punch list is scheduled as a single short activity at the very end, instead of rolling floor by floor as each floor finishes.

Logic checks before you call it done

• Does every long-lead item have a submittal, fabrication, and delivery chain that drives its install?
• Do interiors on each floor depend on that floor's dry-in, not the whole building's?
• Are inspections their own activities, with the work after them depending on them?
• Do finishes that need it depend on conditioned air?
• Does TCO depend on permanent power, fire alarm acceptance, and elevator inspection?
• Is the critical path something you can explain in two sentences? If you cannot, look at it again. What Is the Critical Path Method? is a decent refresher.

Key takeaways

• Procurement of long-lead items is often the real start of the critical path. Model it explicitly.
• Link envelope and interiors to the structure floor by floor, so work stacks up behind the frame.
• Dry-in, permanent power, and conditioned air are the handoffs that control interiors.
• Inspections are hard gates. Give them their own activities and realistic lead times.
• The end of the job is usually driven by building systems and life safety, not by finishes.