Why I stopped making optimistic schedules

My first construction schedule had 47 lines in Excel. Each task with start date, end date, responsible party. All color-coded, formatted, beautiful. I showed it to the client with pride.

The foundation was scheduled for 3 weeks. It took 6.

By week 4, the client was already asking what went wrong. By week 6, he stopped asking. Just looked at the schedule with that face that says “you have no idea what you’re doing.”

The problem wasn’t Excel. The problem was me.

The mistake everyone makes

Construction schedules lie. Not maliciously. Out of optimism. We look at a task and think “if everything goes right, it takes X days.” Then we put X days in the schedule.

But on a jobsite, nothing goes right. It rains during concrete week. The supplier delays the cement. The mason calls in sick Monday. The client changes their mind about the window position.

I learned to multiply my estimates by 1.3. It’s not pessimism. It’s realism. And you know what happens? Sometimes I deliver ahead of schedule. Client is happy. I’m less stressed.

Gantt isn’t about making pretty charts

Everyone knows Gantt charts. Horizontal bars, lines connecting tasks, professional look. Great to show clients.

But the value of Gantt isn’t in the chart. It’s in the dependencies.

When you draw that structure can only start after the foundation cures, and that MEP rough-in must finish before plaster, you’re mapping the critical path. The sequence of tasks that, if delayed, delays everything.

I discovered this too late on a renovation. Thought I could get the cabinetry started while waiting for the tile to arrive. I couldn’t. The cabinet maker needed the floor done to measure the baseboard. Result: three weeks delay because I didn’t think about the dependency.

How I build schedules now

First, I talk to the foreman. Not with drawings in hand, but with open questions. “How long does it take you to do a foundation this size?” His answer is worth more than any productivity table.

Second, I think in packages, not tasks. Foundation. Structure. Framing. MEP. Roofing. Finishes. Within each package, a few main tasks. But I don’t overdo the detail. A schedule with 200 lines is a schedule you abandon by week two.

For typical residential, 30 to 40 lines works. More than that and you’re micromanaging.

Third, and this is important: I document the assumptions. “Foundation estimated at 5 weeks assuming crew of 3 masons and dry weather.” When it’s late, I know what changed. When the client asks, I have an answer.

The phases that always cause problems

Foundation: everyone underestimates concrete curing. It’s not just 7 calendar days. It’s 7 days of adequate curing. If it rained too much, if it got too cold, it might need more time. And loading the structure before full cure is asking for trouble.

MEP: this is where communication fails. The electrician schedules for Tuesday, but the framing won’t be ready. Or worse: it’s ready, but nobody told him. Coordinating subcontractors is a job in itself.

Finishes: the longest and most unpredictable phase. Because it involves client choices (which tile? what wall color?), different suppliers (cabinet maker, stone fabricator, glazier), and a rigid sequence nobody respects. You can’t paint before drywall. Can’t lay floor before plaster dries. Can’t install countertops before the floor.

I’ve seen projects delayed 3 weeks because the client took too long to pick the grout color. Three weeks. Because of grout.

About buffers

Do I add margin to everything? No. Only on the critical path.

If the cabinet maker is a week late, it probably doesn’t affect the final delivery. Cabinetry usually isn’t on the critical path. But if the structure is a week late, everything after it is late too.

My rule: 20% buffer on critical tasks. Zero on the others. This keeps the schedule realistic without inflating the total timeline too much.

And when do I use that buffer? I never tell the crew it exists. For them, the deadline is the tight deadline. The buffer is mine, to absorb surprises without renegotiating with the client.

What I show the client

Two versions of the schedule. One simplified, with main milestones: foundation complete, structure complete, dried in, finishes, handover. That’s what they see.

The other, detailed, stays with me and the foreman. With all tasks, dependencies, responsible parties. That’s the working tool.

Why? Because the client doesn’t need to know that “floor underlayment” is two days behind. They need to know if they’ll get their house on time. Too much information creates unnecessary anxiety.

Updating matters more than creating

The best schedule in the world is useless if you make it once and never look at it again.

Every Friday, 15 minutes. What got done this week? What was planned and didn’t happen? Why? What changes for the coming weeks?

This simple routine has saved me many times. Because when you update weekly, you catch the delay when it’s 3 days. Not when it’s 3 weeks.

And more: you build a history. On the next project, when you need to estimate how long a foundation takes, you won’t guess. You’ll look at the record from the previous one.

The real deal on timelines

After a few dozen projects, I developed intuition. I know a single-story foundation takes 4 to 5 weeks. That a two-story structure takes 6 to 8. That finishes always, always, take longer than I think.

But intuition doesn’t replace process. I keep making schedules, keep updating, keep documenting. Because intuition fails when the project is different from the pattern. And every project is different from the pattern somehow.

The secret isn’t making a perfect schedule. It’s making an honest schedule, updating frequently, and having history to learn from mistakes.

That first 47-line schedule? I still keep it. To remember never to promise 3 weeks for a foundation again.

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