Everybody films the crane. It’s a good show — a house arrives on trucks, and by dinnertime there’s a building standing where there wasn’t one. What nobody films is the six weeks before it, which is when the day was actually decided.
So here’s what really happens, and the handful of site decisions that determine whether it goes well.
The trucks roll in early. The crane sets up and gets its outriggers on solid ground. Before anything gets lifted, the set crew checks your foundation against the drawings, because the foundation is the one piece of this that got built outdoors in field conditions.
Then the modules go on. They aren’t lifted dead level — the crew tips them slightly and lands one outside corner at a time, then pinches toward the middle. The first module takes the longest, because once it’s down and released, everything else is measured off it. If the first box is wrong, the whole building is wrong.
After placement, the mate walls get strapped and fastened together. Hinged roof sections come up, eaves fold out, and the building starts looking like a building.
A straightforward house is usually a day. A more complicated one is two.
And then the part people don’t expect: the set isn’t the end of site work; it’s the start. Button-up, marriage line finishes, roofing and siding at the mate lines, mechanical connections, and everything else that makes an assembled building a finished one. The crane leaves. The work doesn’t.
On a stick job, a bad decision shows up as a slow week. You lose ground, and you make it up.
Set day doesn’t work that way. Six weeks of other people’s decisions all come due at once, in one morning, in front of a crane that bills by the hour and a set crew that’s booked somewhere else tomorrow. If the site isn’t ready, nothing about that day is negotiable. You don’t get a partial set. You get a postponement, and postponements cost real money — crane, crew, trucks, and a rescheduled slot you may not like.
That’s why almost everything below happens weeks before the trucks roll.
The foundation is a measurement, not a pour. This is the big one. Modular needs tighter tolerances than most site crews are used to — roughly a quarter inch of level over the length of a wall, with diagonals matching within a half inch. That’s not a suggestion; it’s what lets the boxes land square and the mate lines close. Get the as-built verified in writing, well before the trucks are loaded, and check it again if there’s been any settling since the pour. Finding a quarter-inch problem on a Tuesday is a phone call. Finding it on set day is a crane sitting idle.
Access is a route, not a driveway. Somebody needs to physically drive the entire route, especially the last quarter mile. Trucks need wide turns, gentle grades, and firm surfaces. Low wires, tight corners, soft shoulders, and a tight corner at a driveway culvert are all cheap problems before set day, and expensive ones on delivery morning. In Maine, add mud season to that list — a road that hauls fine in August can come apart when the frost goes out.
The crane needs ground, not just space. Plan on 25 to 40 feet of working area beyond the foundation footprint on at least one side, often two, with stable ground under the outriggers and a clear path overhead. Crane setups also have to stay a minimum of 15 feet from power lines. If a line needs to be moved or dropped, that’s a utility lead time measured in weeks, so find it early.
Route the utilities during the foundation phase. Water, sewer, electric, and gas should be located and stubbed while the pad and foundation are going in. Relocating any of it after the building is sitting on top is expensive, ugly, and entirely avoidable.
Assign the weather call in advance. High winds stop a set. Saturated ground stops a set. Somebody has to own that decision, and everyone has to know who it is and by when they’ll make it. “Let’s see how it looks in the morning” is how you end up paying for a crane that never picked anything up.
Have the button-up crew ready that same week. An open building is a wet building. The gap between set day and weather-tight is where we see the most damage and the most finger-pointing. Schedule it as part of the set, not as the next thing on the list.
The projects that go smoothly all do the same unglamorous thing: they hold a pre-set meeting a couple of weeks out with the GC, the set crew, the crane operator, and the excavator in the same conversation.
Foundation as-built verified. Route driven, not assumed. Crane position agreed on and cleared. Weather call assigned to a name. Button-up on the schedule.
That meeting takes an hour. It is the cheapest hour on the whole project, and skipping it is the most expensive thing you can do for free.
This is the same thing I’ve been saying since the first post, showing up in a different place.
Modular doesn’t remove work. It moves it earlier — the design decisions, the procurement, the site readiness, all of it upstream of the day the trucks arrive. When people say a modular project “went sideways,” what they almost always mean is that something that needed to be settled in week four didn’t get settled until week ten.
Set day is just where you find out.
Do the work early, and it’s the best day on the job. There’s nothing else in construction quite like watching a building go up in an afternoon, and I’ve never gotten tired of it.
Next week: why multifamily is where this makes the most sense right now, and what’s different about pricing one.
— Thatcher
