Mechanical services — air conditioning included — get sequenced wrong more often than any other trade on a residential build. Not because anyone’s incompetent, but because it sits at the intersection of frame, electrical, and finishing trades, and if it’s not explicitly programmed, it defaults to “whenever there’s a gap.”
Where mechanical services actually belong in the program
Duct runs and rough-in need to happen after frame but before insulation and ceiling fix — miss that window and you’re either cutting into finished ceilings or compromising the duct layout. Electrical rough-in for AC controls needs to be coordinated with the sparkie at the same stage, not sequenced separately. If you’re still deciding between ducted and split system, that decision (see our decision framework) needs to be locked in before this stage of the program, not during it.
The knock-on effect of getting this wrong
A mechanical services trade booked too early sits around waiting for frame; booked too late and it holds up insulation and ceiling fix behind it, which holds up plastering, which holds up everything downstream. This is exactly the kind of trade-sequencing failure we cover in more detail in our piece on HVAC as an afterthought.
Material availability matters here too — duct, insulation and unit stock delays can blow out a program even when sequencing is right. We touch on that in our piece on managing material lead times, and for procurement support specifically, we’ve found Covert Procurement useful for builders managing multiple concurrent Hills District jobs.
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