Why do some building types finish closer to plan than others?

TL;DR: On healthcare and education builds, the median activity finishes within three weeks of the due date in the latest revised schedule. On residential and commercial builds, the median overrun runs five to six and a half weeks, roughly double. In this blog, we look at what might explain that gap, from penalty exposure to client structure and what it means for how planners should be setting durations in the first place.

A construction schedule is made up of thousands of individual activities, each with its own planned end date. 

Some activities contain what is known as time risk allowance. This refers to intentional spare time built in so that an issue within one activity doesn’t automatically delay the ones after it. 

Or they may have float. Unlike time risk allowance, this isn’t built in deliberately. It’s simply a byproduct of how the schedule comes together: the time an activity can be delayed before that delay starts to matter. Free float is how much delay an activity can absorb before it pushes back the activities that follow it. Total float is how much delay it can absorb before it pushes back the project end date itself. Either way, there’s often legitimate wiggle room to finish later than planned without the project falling behind.

But, as we all know, this wiggle room isn’t usually used evenly across projects and activities. So my team and I at the Buildots Intelligence Lab decided to measure it. The question we asked: “For every activity that reached 100% complete, how far past its planned end date did it actually land?”

We took the most recent schedule and calculated the median activity overrun for each project, specifically measuring the slip of individual activities within a project. Because we used the most recent schedule, in many cases, the data you’ll see below shows you overrun against a plan that has already been revised at least once.

What we found

An interesting difference jumped out immediately. On healthcare and education projects, the median activity reaches completion within three weeks of its planned date. On residential and commercial projects, the median activity runs measurably further behind – to the tune of double the overrun.

Vertical	Median activity overrun
Healthcare	+2.6 weeks
Education	+2.9 weeks
Residential	+5.2 weeks
Commercial	+6.4 weeks

One thing worth flagging, though we can’t make much of it yet: high-rise residential appears to be pulling the overall residential number in a better direction (+3.4 weeks overrun) compared to other residential development (+6.3 weeks overrun). The sample isn’t big enough to split out and call an official finding, so the table above uses the combined data. It’s something we’ll keep watching.

Why is this gap happening?

While we can’t draw definitive conclusions, we can offer some candidate explanations worth testing:

Different penalty structures

Education has an obvious version of this. The school year starts on a fixed date whether or not the building is finished, and many education contracts carry damages for missing it. This inflexibility comes at a cost that slipping a commercial handover often doesn’t have. But the underlying mechanism, how exposed a project is to overrun penalties, could plausibly differ by building type more generally, not just for education.

Mission-critical discipline

Healthcare has different pressures and still lands close to plan. We can only speculate why: the impact in relation to people not getting the medical treatment they are expecting on time, or something about how healthcare programs are managed that this dataset can’t show us.

Different client organizational structures

Different client types (for example, public bodies and private clients) may simply be structured to manage projects differently – whether it’s different oversight cadence, different risk tolerance or different decision-making chains. That alone could produce a gap like this.

More realistic planning

Another possibility is that healthcare and education schedules are simply written with more realistic durations from the start. If so, the lower overrun would reflect more realistic planning rather than better building.

So what does this mean?

For planners

This research really highlights the importance of data-driven scheduling. It’s important for planners to have access to recent data on how similar activities have performed on past projects, not generic or outdated benchmarks, and account for the variables that actually move duration – whether it’s project type, geography or something else entirely.

For the industry

This raises a real question about whether the discipline visible in healthcare and education is something transferable, or whether it’s a structural artifact of how those sectors are procured and governed.

Over to you

If your healthcare or education projects hold activities closer to plan than your residential or commercial ones, we’d like to know what you think is actually driving the difference. Penalty exposure, client structure, something else? Get in touch.

Methodology

• Metric: median activity overrun (planned vs. actual completion date) per project, then median across all projects in each vertical
• Schedule basis: most recently revised schedule, not original baseline
• Sample: 150 completed projects
• Vertical grouping: Healthcare and Education vs. Residential and Commercial
• Caveat: high-rise residential shown as a directional sub-pattern only, sample size insufficient to report separately