Homes take longer to build than they used to.
Not all of it is the builder's.

The Australian Bureau of Statistics publishes average time from commencement to completion for new private houses, quarterly and by state. In September 2019, the last full quarter before the pandemic period, the average new detached house took 2.2 quarters to complete, just under seven months. By June 2024 that had risen to 3.3 quarters, just under ten months. A 50 per cent increase in average build time, published by the ABS in its article Home Building Through the Pandemic.

The pipeline figures give the same period its scale. At the national peak in March 2023 there were 104,315 private new houses under construction, against a pre-pandemic normal near 70,000 (70,306 in June 2018, on the ABS series). More sites were open than at any point in recent memory, and each of them was occupying a construction slot materially longer than it would have before 2020.

Two things need saying before any of it is used. First, these are point-in-time figures and they will date. More recent ABS releases show a modest easing as supply chains stabilised, while build times remain materially above pre-pandemic norms, so anyone relying on a number for a decision should pull the current quarter from the ABS rather than quoting this page. Second, this is a national average across every house type, region, price point and builder. It describes a period. It does not describe your job, and it is not a benchmark anybody should be measured against.

Why it matters

Because build duration is the quantity a residential contract is written against, the quantity preliminaries are consumed by, and the quantity that decides how many jobs a business can carry at once. A builder who understands what elapsed time is made of can shorten the parts that are theirs and price the parts that are not. A builder who treats build duration as weather, in the sense of something that simply happens, prices it wrong at tender and argues about it later.

The single most useful distinction on this subject is between the days work happens and the days that pass. Working days are the days a trade is on site doing something. Elapsed days are every day between commencement and completion: weekends, public holidays, the Christmas shutdown, wet days, drying-out days, inspection waits, delivery waits and decision waits. Contracts measure elapsed time. The ABS measures elapsed time. Clients experience elapsed time. Programmes, almost universally, are built in working days.

That mismatch is where most build-period arguments start. A programme showing 120 working days is not four months, it is closer to six once ordinary non-working time is put back, and closer again to seven if the job runs through January. Nothing has gone wrong in that conversion; it is arithmetic. What goes wrong is quoting the first number and being measured on the second.

The deeper point is what fills the gap. On a detached residential job the intervals between work are not incidental to the duration, they largely are the duration. Trades work in short bursts and then leave, and the wait for the frame crew is set by their next available slot rather than by how long framing takes. Which is why the useful question is never how fast your trades work. It is how long your job spends waiting.

The operator's observation is that most builders try to shorten the wrong half. When a job runs long the instinct is to push the trades and add hours, all of which acts on working time. But on a job that has drifted six weeks it is rare to find more than a few days of it inside the actual work. The rest is sitting in intervals, and the intervals were created weeks earlier by a selection that was not closed, an order that was not placed or a slot that was not confirmed. By the time drift is visible, the decisions that caused it are already behind you.

Which is why the builders who run short durations tend to be unremarkable on site and very organised in front of it. Selections closed before the slab. Long-lead items identified at tender and ordered against confirmed dates rather than hopeful ones. Inspections booked against the forecast date and moved rather than booked late. Trade slots confirmed in writing with a date, not held on a friendly phone call. None of this is difficult and all of it is administrative, which is precisely why it is the part most often skipped.

The second discipline is measuring your own duration rather than the industry's. A baseline programme with actual dates recorded against it will tell you, within two or three jobs, exactly which stage in your business runs long. It is almost never the stage anybody guesses. When the delay does run beyond what the build period allowed for, the record is also what an extension of time stands on, which is the difference between a moved completion date and an argument.

Where software fits the workflow

The reason elapsed time goes unmanaged is not that builders do not care about it. It is that the waits live in different places: the order is in an email, the inspection is in a diary, the selection is in a phone call and the programme is on a wall. Nothing joins them, so nobody sees the interval forming. In VIABUILD the construction schedule holds the baseline, the actual dates and the dependencies on the same understanding of the job as the orders and the site record, so a slipped delivery or a late decision shows its downstream effect on every following trade immediately rather than being discovered a month later. The judgement stays with the builder; what the software contributes is that the drift is visible while it is still small.

Build-time figures get quoted loosely, in both directions. The points below are labelled by evidence class so a reader can see which are measurements, which are conventions and which are judgement.

• Measurement. The ABS series measures elapsed time from commencement to completion for new private houses, published quarterly and by state. It is a national average across all house types and regions. It does not measure working days, does not isolate causes and does not describe any individual builder.
• Measurement. The figures cited here, 2.2 quarters in September 2019 rising to 3.3 quarters by June 2024, and the pipeline peak of 104,315 houses under construction in March 2023 against 70,306 in June 2018, are drawn from ABS publications current at the time of writing. They are point-in-time and will date.
• Attributed observation. The Reserve Bank of Australia named wet weather as a factor constraining construction output in its September 2023 Bulletin on recent trends in Australian productivity. That is a central bank observation about construction generally, not a quantified attribution for detached housing.
• Common practice. Residential build periods commonly carry an allowance for anticipated wet weather and holidays inside them, and many contracts state the weather allowance. Whether a given delay is inside or beyond that allowance is the first question of any claim, and the answer is in your contract rather than in any national figure.
• Professional recommendation. State and territory building regulators, and standard-form contracts published by HIA and Master Builders, govern how completion dates and build periods are expressed in your jurisdiction. Confirm the current position there before relying on general information, including this page.

Illustrative only, not a benchmark. Two builders start the same four-bedroom detached house in the same suburb in the same month, on the same programme of 118 working days. The first builder closed selections before slab, ordered windows and cabinetry at contract signing against written lead times, and booked the frame inspection the day the frame was scheduled to finish rather than the day it did. When a wet fortnight lands at slab stage, the crews are re-sequenced within the week and the frame slot is renegotiated in writing the same day it becomes clear it will be missed.

The second builder does what a busy builder does. Selections are still moving at frame stage because the client is deciding, windows are ordered when the frame is up, the inspection is booked when the carpenter calls to say he has finished, and the same wet fortnight is handled by phone calls that nobody writes down. Nothing on this job is done badly. Every single item is done a fortnight later than it could have been.

The first house reaches practical completion around seven months from commencement. The second reaches it around ten. The difference is not craftsmanship, effort or luck, and almost none of it is working time. It is six or seven intervals, each of two or three weeks, created by decisions taken well before the interval appeared. That is what a build-time increase looks like from inside a single business, and it is why national averages are interesting and your own baseline is useful.

Elapsed time (every calendar day between commencement and completion, which is what contracts and the ABS measure), working days (days on which work is actually performed), build period (the duration the contract allows between commencement and completion), commencement (the ABS reference point for the start of a build, distinct from contract signing), long-lead item (a component whose supply queue is longer than the stage it belongs to), trade slot (the booked window a subcontractor holds, lost rather than deferred when a job slips), decision latency (the elapsed time between a question being asked and answered), float (the time a task can slip without moving the finish date), baseline (the programme the job started with, against which actual dates are measured). Definitions for the wider vocabulary live in the construction glossary.

The same arithmetic applied across a whole business, and across a national pipeline, is its own subject; the next reference is construction pipeline capacity.

• Australian Bureau of Statistics, Home Building Through the Pandemic , the source of the completion-time and pipeline figures on this page.
• Australian Bureau of Statistics, Building Activity, Australia , the quarterly series for commencements, completions and work under construction. Pull the current release before quoting any number from this page.
• Reserve Bank of Australia, Recent Trends in Australian Productivity, Bulletin September 2023 , where wet weather is named as a constraint on construction output.
• Your state or territory building regulator, for how build periods and completion dates must be expressed in a domestic building contract in your jurisdiction.
• Your own baseline programmes and actual dates, which are the only source that says anything about your business. The national series describes the period; only your record describes your duration.