A schedule is a list of dates. A programme is a network of dependencies that tells you what happens to the end date when one of those dates slips. Only one of them is any use when something goes wrong.
Programme vs Schedule: What Your PM Manages — practical guidance from the team running construction project management on the Garden Route. Below is what makes a programme a programme, how to read one you have been given, and what a project manager is actually managing when they manage time.
The difference, and why it matters
A schedule says: foundations in week two, walls in week four, roof in week seven. It is a statement of intent, and it is perfectly useful right up until something changes.
A programme says: the roof cannot start until the walls are complete, the walls cannot start until the slab has cured, the slab cannot be poured until the municipal foundation inspection has passed, and that inspection cannot be booked until the reinforcement is fixed. It is a network of logic.
The difference shows the moment a delay happens. Ask a schedule what a two-week delay to the windows does to your completion date and it cannot tell you. Ask a programme, and it can — because the answer depends entirely on whether the windows are on the critical path.
That is the whole point. Construction always deviates from the plan. The value of a programme is not that it predicts the future accurately; it is that it tells you the consequence of a deviation while you can still do something about it.
Critical path and float
Two concepts do most of the work.
The critical path is the longest chain of dependent activities through the project. Every activity on it, delayed by a day, delays completion by a day. Every activity not on it has some slack.
Float is that slack — how long an activity can be delayed before it starts affecting something else. An activity with ten days of float can slip by a week and nothing happens to your completion date.
This is why not all delays are equal, and why an experienced project manager sometimes seems relaxed about one thing and immovable about another. A week’s delay to the landscaping and a week’s delay to the roof are entirely different events.
The critical path also moves. As activities complete and others slip, a chain that had float can become critical. A programme that is updated is telling you where the pressure is now; a programme printed once at the start and pinned to a wall is decoration.
And float belongs to someone. Whether spare time in the programme is available to the contractor or to the client is a real contractual question on larger projects, and it is worth knowing the answer before it is contested.
Reading a programme you have been given
Four checks will tell you whether you are holding a management tool or a marketing document.
1. Does it show dependencies? A bar chart with bars but no logic links is a schedule. If nothing shows what depends on what, nobody can tell you the consequence of a slip.
2. Does it include the things that are not construction? Plan approval, municipal and NHBRC inspections, procurement lead times, client decision dates, and any work the client is doing themselves. A programme showing only trades is showing you half the project and hiding the half that usually causes the delay.
3. Is there float, and is it visible? A programme with no slack anywhere is a programme in which the first bad week becomes a delay to completion. Honest programmes carry contingency and say where it is.
4. Is it being updated? Ask when it was last revised against actual progress. A programme that has not moved since week one is not tracking anything.
And ask for a decision schedule alongside it — a list of what you have to choose and by when. It converts a vague obligation into dates, and it is the single most effective tool for keeping a build on time.
What a project manager is actually managing
Managing time on a construction site is not chasing people. It is managing the constraints that make chasing necessary.
Procurement. Identifying long-lead items at the start and ordering them against the programme rather than against the work face. Windows, cupboards, stone tops, specialist tiles, switchgear. A lead time nobody planned for is indistinguishable from a delay.
Information. Making sure the drawings, details and decisions a trade needs are available before that trade arrives, not while they are standing there.
Sequence and interfaces. Making sure trades do not arrive on top of each other, and that each one leaves the work in the state the next one needs.
Inspections and approvals. Booking them, and building the waiting time into the programme rather than being surprised by it.
Early warning. Raising a problem while there is still float to absorb it. This is the single highest-value thing a project manager does, and it is why contract forms like NEC4 are built around it.
And weather. On the Garden Route, sequencing to reach weathertight before the wet part of the year is the biggest single programme decision on a build, and it is worth reorganising a start date for.
Frequently asked questions
What is the difference between a programme and a schedule?
A schedule is a list of activities and dates. A programme is a network showing which activities depend on which, so it can tell you the consequence of a delay rather than just what you had hoped for. When something slips — and it always does — only a programme can tell you whether the end date moves with it.
What is the critical path?
The longest chain of dependent activities through the project. Anything on it, delayed by a day, delays completion by a day. Anything not on it has float — slack it can absorb before it affects anything else. This is why not all delays are equal, and why a week lost on the roof and a week lost on the landscaping are completely different events.
What is float and who owns it?
Float is the amount of time an activity can be delayed before it starts affecting the project completion. On larger contracts, whether that spare time belongs to the contractor or to the client is a genuine contractual question, because it determines who benefits when things go well and who carries it when they do not. It is worth establishing before it is contested rather than after.
How often should a programme be updated?
Regularly enough that it reflects reality — commonly monthly on a residential build, more often on a fast or complex one. A programme that has not been revised since week one is not tracking anything, and its critical path is no longer where it says it is. Ask when it was last updated against actual progress; the answer tells you whether it is being used or displayed.
What is a decision schedule and do I need one?
A list of every selection you have to make and the date by which each one is needed for the programme to hold — finishes, fittings, sanitaryware, colours, anything the contractor cannot order or install without your choice. It is the most effective single tool for keeping a build on time, because late decisions convert directly into standing time, which is the most expensive kind of delay since nothing is being produced.
Who is responsible when a project runs late?
It depends on the cause, and a proper contract sets it out. Delays caused by the contractor are theirs. Delays caused by client changes, late decisions, late client-supplied materials or late approvals typically entitle the contractor to an extension of time and sometimes to costs. Exceptional weather is usually a ground for time without cost. This is one of several reasons to use a recognised standard contract rather than a quotation.
Related reading
- How we run a build programme
- Timeline of a new home build
- JBCC vs NEC4 vs PBA
- Construction project management
Want a programme, not a bar chart?
Ours shows the dependencies, the approvals, the lead times and your decision dates — so when something moves, you find out what it costs you in time before it has happened.
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