In 500+ projects, the same problems show up. Here's the list, with price tags.
I have a bias I should disclose upfront: after 24 years and more than 500 commercial projects, I've stopped being surprised by construction problems. I've seen the same ones enough times that I can usually tell in the first conversation whether a project is heading toward a clean close or toward an expensive lesson.
The expensive lessons are avoidable. That's the frustrating part. They're not random — they follow a pattern. And the pattern is consistent enough that I can name five of them here, with reasonable accuracy about what each one costs when it hits.
Mistake 1: Executing the GC contract before completing design
What it looks like: An operator is excited about a site. They've selected a general contractor. The architect has schematic drawings but not construction documents. The GC has given them a price — "preliminary, subject to final drawings." The operator signs the AIA contract and starts the clock.
What happens next: The construction documents come in and the scope changes. The structural engineer adds a requirement that wasn't in the schematic drawings. The mechanical engineer specifies equipment that's more expensive than the GC's preliminary allowance. The cost of the project is now different from the number in the contract, and the operator is in a price negotiation with a contractor who knows they're already committed.
What it costs: Change orders driven by design development after contract execution typically run 5-15% of total project cost. On a $5M build, that's $250,000 to $750,000 in additions that didn't exist in the original price — and that the operator has limited leverage to negotiate because they're already under contract.
The fix: Don't sign the GC contract until the construction documents are at least 90% complete. A contractor who prices a complete set gives you a number you can hold them to. A contractor who prices a schematic gives you an estimate that will change.
Mistake 2: Ordering FFE too late
What it looks like: The building is at 80% completion. Walls are up, MEP rough-in is done, flooring is going in. The operator starts shopping for equipment.
What happens next: They find that the commercial kitchen range hood they need is 18-24 weeks out. The walk-in cooler system they specified is 14 weeks. The custom millwork for the front counter is 16 weeks. The building will be ready for occupancy in 8 weeks. The CO is delayed because the equipment that makes the building functional hasn't arrived.
The GC bills for delay. The trades who were scheduled for final connections have to remobilize. The operator's opening date slips. A month's revenue is lost.
What it costs: Delay costs on a commercial project run $5,000-$20,000 per week depending on the size of the project and the crew size. On a 4,000 square foot QSR build with 10 weeks of delay, that's $50,000-$200,000 in direct costs before accounting for lost revenue from the delayed opening.
The fix: Equipment procurement decisions belong in the design development phase, not the construction phase. Get lead times from your equipment vendors before you set your construction schedule. Build the schedule backward from the equipment delivery dates, not forward from groundbreaking.
Mistake 3: Accepting the first MEP bid without a takeoff
What it looks like: An operator gets a bid package back from three general contractors. The GC's MEP numbers look significantly different from each other — one has MEP at 19%, one at 26%, one at 31%. The operator selects the low bidder, partially because the MEP number is lower.
What happens next: The low MEP number was based on a rough percentage of total construction cost, not on a detailed mechanical, electrical, and plumbing takeoff. When actual subcontractor bids come in during construction, the MEP numbers are higher than the GC's allowance. Change orders follow.
What it costs: The gap between an estimated-percentage MEP budget and an actual-takeoff MEP budget is typically 8-15% of the MEP line, which on a $1.3M MEP budget is $104,000 to $195,000 in unbudgeted exposure. On projects where the MEP was significantly under-estimated, the gap is wider.
The fix: Ask the GC directly: "Is your MEP number a percentage estimate or a subcontractor quote?" A percentage is not a committed number. If the GC hasn't received actual MEP sub bids, the MEP line in their budget is an allowance, not a price. Get a detailed MEP takeoff before signing off on the budget. This is standard practice for any CM worth their fee.
Mistake 4: Treating permits as the architect's problem
What it looks like: The operator assumes that the architect files for permits and they'll be notified when the permits are ready. The project timeline is built around the GC's planned start date.
What happens next: The municipality has a 12-week plan review cycle. The fire marshal has comments on the life safety plan that require a design revision and resubmission. The resubmission goes back in the queue. The permit takes 22 weeks instead of the planned 8 weeks, and the GC's mobilization window is gone. The project is delayed before the first shovel is in the ground.
What it costs: A delayed permit on a $5M build with a 10-week schedule impact costs the project $100,000-$300,000 in carrying costs, GC schedule inefficiency, and delayed opening revenue. In jurisdictions with unpredictable review cycles, permit delay is one of the most expensive risks a developer faces — and one of the least managed.
The fix: Treat permitting as a project management function, not a passive administrative step. Know the review cycle in your jurisdiction before you set your schedule. In slow-review municipalities, use a permit expediter — someone who knows the reviewers, manages the queue, and flags when a resubmission is needed faster than the standard turnaround. Permit expediter fees typically run $5,000-$15,000 and can compress the timeline by 4-8 weeks.
The wry observation: I've watched operators spend 90 days optimizing their contractor selection and then lose 12 weeks at the permit desk because no one was watching it.
Mistake 5: Budgeting for the best-case site
What it looks like: An operator signs a ground lease or purchase agreement on a site based on an initial budget that assumed clean site conditions — flat grade, readily available utilities, no environmental unknowns. The budget is tight but workable.
What happens next: The geotech report comes in and shows unstable soil conditions requiring a deeper foundation or a different foundation type. Or the Phase I environmental assessment reveals recognized environmental conditions that require a Phase II investigation and potentially remediation. Or the civil engineer identifies a drainage issue that requires a detention pond that wasn't in the original scope.
Site conditions are the one category of cost that's genuinely difficult to predict before you drill. Every other budget line — structure, MEP, interiors, FFE, soft costs — can be estimated with reasonable accuracy from the design documents. Site costs can't, until you have data.
What it costs: Site condition surprises run from $50,000 (minor utilities conflict) to $500,000+ (significant soil remediation, major drainage work, complex foundation redesign). On projects where the site appeared clean and wasn't, the surprises have been the most expensive single line item on the change order log.
The fix: Do the site investigation work before you finalize your budget. A geotech report costs $5,000-$12,000. A Phase I environmental assessment costs $1,500-$4,000. Together they give you the information you need to budget the site correctly. If the site conditions are adverse, you know before you've committed to a construction contract. If they're clean, you've spent $10,000-$15,000 to confirm a $400-600K budget line.
That's the best money you'll spend in preconstruction.
The common thread
Five mistakes. They look different on the surface — timing, procurement, due diligence, permitting, site selection. But they're all the same problem: decisions made with incomplete information, at stages where the incomplete information was knowable.
The GC contract signed before the drawings were complete: the information was coming, the operator didn't wait for it. The FFE ordered late: the lead times were available, the operator didn't ask for them. The MEP number accepted without a takeoff: the question was askable, no one asked it. The permit timeline treated as someone else's job: the municipality's review cycle was public information. The site budgeted before the geotech was done: the investigation was schedulable before the LOI was signed.
CM doesn't eliminate problems. It eliminates the problems that are preventable by watching the right things at the right time. In 500+ projects, these five are the most preventable.
In preconstruction on a new build? We work with operators at the stage where these decisions are still correctable. If you want a read on your current process or a second set of eyes on your budget and schedule assumptions, that conversation is worth having before the GC contract is signed — not after.