TL;DR — Scheduling concrete pours in Australia
- Concrete is single-shot. No second chances once it’s in the form — weather, crew and supplier all have to align on the same day.
- Ideal pour temp 10 – 25°C. Below 5°C needs cold-weather mix and insulation; above 32°C needs a retarder and a cold mix.
- Avoid pouring if the 24-hour forecast shows rain. Fresh concrete is most vulnerable in the first 4 – 8 hours.
- Book the truck 24 – 72 hours ahead and respect the 90-minute drum-time limit from batch plant to placement.
- Short-notice cancellation fees are $500 – $1,500 — build a Plan B and a clear go/no-go decision deadline the day before.
Of every trade on a construction site, concreting punishes scheduling mistakes the hardest. A carpenter can re-cut a stud. A sparky can re-pull a cable. A concreter who pours in the wrong weather or misses the delivery window is paying to demolish, cart away and start again. The job is single-shot: once the truck tips and the formwork fills, the next 24 hours decide whether you’ve built a slab or a $20,000 problem.
This guide is a practical playbook for Australian builders, concreters and owner-builders on how to schedule a concrete pour so the weather, the crew, the supplier and the curing window all line up on the same day. It covers the weather thresholds that should trigger a deferral, how to coordinate the truck and the pump, what the supplier’s 90-minute drum rule means for your sequencing, and how to use weather-aware scheduling tools so rain forecasts hit your inbox before you commit to a pour.
Why scheduling concrete is harder than other trades
Most trades give you a second chance. Concrete doesn’t. Three things make pour-day scheduling uniquely brutal:
- Irreversibility. Once the chemical reaction (hydration) starts, the clock is running. You can’t pause it, undo it, or hold the truck for “10 more minutes” without consequences.
- Compound dependencies. Form crew, reo crew, concrete supplier, pump truck, finishers, and weather all have to converge on the same morning. A failure in any one of them cascades to all the others.
- Weather is the wildcard you can’t control. You can move people, gear and trucks. You can’t move a cold front. A pour booked Monday morning that hits a Sunday-night storm is a write-off whether you’re ready or not.
That’s why the actual skill in scheduling a pour isn’t picking the right day — it’s setting up a decision framework that tells you, the day before, whether to go or to defer. The rest of this guide gives you the thresholds and the logic to do that consistently.
Weather thresholds for concrete pours
Temperature, rain and wind all change the chemistry of the mix as it cures. Get any one of them wrong and you lose strength, get cracking, or have to grind the surface back. The table below is the working set of thresholds Australian crews use day-to-day.
| Condition | Ideal | Caution — mitigate | Defer the pour |
|---|---|---|---|
| Air temperature | 10 – 25°C | 5 – 10°C (cold-weather mix, insulation blankets); 25 – 32°C (retarder, evening pour) | Below 5°C without cold-weather precautions; above 32°C without a cold mix and retarder |
| Rain (next 24 hr) | No rain forecast within 24 hr of pour start | Light showers forecast 12 – 24 hr after pour — cover with poly + retain finishers | Any rain forecast in the first 4 – 8 hours after placement |
| Wind | Calm to light breeze (under 20 km/h) | 20 – 40 km/h — apply curing compound or fog spray, shade the slab | Sustained 40 km/h+ on exposed sites — evaporation will outpace curing |
| Humidity | 50 – 80% | Under 50% — combine with shade and curing compound | Under 30% combined with high wind and 30°C+ air temp (plastic shrinkage crack territory) |
| Direct sun | Overcast or shaded site | Full sun — shade screens, white-pigmented curing compound, early start | Surface drying visibly outpacing finishers — abort and re-plan |
| Frost overnight (next 48 hr) | Min temp >5°C for 48 hr | Min temp 0 – 5°C with insulation blankets in place | Sub-zero forecast within 24 hr of pour — freeze damage risk |
Thresholds align with AS 3600 and the Cement Concrete & Aggregates Australia “Hot and Cold Weather Concreting” guidelines. Specialist mixes (mass concrete, post-tensioned slabs, structural commercial) may have tighter site-specific limits — always defer to the engineer’s spec.
Why these numbers matter chemically
Hydration — the reaction between cement and water that makes concrete go hard — runs fastest around 21°C. Below 10°C the reaction slows; below 5°C it nearly stops, which is why a slab poured at 3°C can still be soft 24 hours later and useless if it freezes. Above 32°C the reaction accelerates, the mix loses workability before you can finish it, and the surface dries faster than the bulk can cure — the classic recipe for plastic shrinkage cracking.
Wind and low humidity don’t change the chemistry, but they accelerate surface evaporation. If the surface loses water faster than the mix can bleed water back to the top (about 1 kg/m²/hour is the danger line), you get crazing, dusting and shrinkage cracks. Curing compound, shade and fog spray all exist to fight this single problem.
Curing temperature targets
Curing is everything that happens after the truck leaves. The slab keeps gaining strength for weeks; the first 7 days are where 70% of that strength forms, and the first 24 hours are where most pour-day mistakes turn into cracks.
- 21°C is the optimal curing temperature for strength development. The further from 21°C, the slower the curve.
- Keep the slab moist for at least 7 days. Plastic sheet, wet hessian, or a sprayed curing compound all work.
- Hot-weather pours: shade screens, white curing compound, and fog spray for the first 24 hours.
- Cold-weather pours: insulation blankets to hold the heat of hydration in; don’t strip them until ambient is back above 5°C.
- Don’t load the slab until specified. Foot traffic at 24 hours, light vehicles at 7 days, full design load at 28 days.
If you’re costing out a job and want to sanity-check the concrete order, our free Concrete Cost Calculator sizes the m³ order, builds in a wastage allowance, and gives you a delivered price.
When to defer a pour — the decision framework
The single most useful thing you can do as a builder is set a clear go/no-go deadline the day before and run a fixed checklist against it. The framework below is the version that crews actually use; it works because it’s binary at the point of decision.
The 4pm-day-before decision framework
By 4pm the day before the pour, run through these five checks. One “no” defers the pour.
- BoM 24-hr forecast: Less than 30% chance of rain in the first 8 hours after pour start? If no — defer.
- Temperature window: Forecast min/max within 5 – 32°C without mitigation? If no, do you have the mitigation (cold mix, retarder, blankets, shade) confirmed and on site? If no — defer.
- Site readiness: Formwork signed off, reo placed and chaired, vapour barrier laid, services in slab confirmed, access cleared? If no — defer.
- Crew confirmed: Concreter, finishers and labourers all confirmed by SMS, on site 30 minutes before the truck? If no — defer.
- Supplier & pump confirmed: Batch plant has the order, pump truck slot confirmed, water and power on site? If no — defer.
If you defer, call the supplier before 6am on pour day to avoid the worst of the short-notice cancellation fee.
Worked examples
- Melbourne, July, footing pour booked 7am Wednesday. Forecast Tuesday 4pm: 4°C overnight, top of 11°C, 60% chance of rain from 11am. Defer. Both temp and rain triggers fail.
- Brisbane, January, slab pour booked 6am Friday. Forecast Thursday 4pm: 24°C at 6am rising to 35°C by midday, 10% rain chance, 15 km/h breeze. Go — with mitigation. Start at 5am, order a cold mix with retarder, set up shade screens, have curing compound on site, finish before 11am.
- Perth, October, driveway pour booked 8am Saturday. Forecast Friday 4pm: 22°C, no rain, 50 km/h sea breeze forecast from 11am. Defer or bring forward. The wind will outpace your finishing window.
- Sydney, May, suspended slab booked Monday 7am. Forecast Sunday 4pm: 16°C, light showers Sunday night clearing by 3am Monday, dry from then. Go. Rain clears before pour start; first 4 – 8 hours of curing are dry.
Supplier coordination: the logistics layer
The weather decides whether you can pour. The supplier decides whether you’ll have anything to pour with. Three things matter here: the booking lead time, the delivery slot, and the 90-minute drum rule.
Booking lead time
- Residential pours under 10 m³: Book 24 – 48 hours ahead in metro Australia. Peak season (October – March) push to 72 hours.
- Larger pours (10 – 30 m³): 3 – 5 working days — the plant has to sequence trucks back-to-back.
- Specialty mixes (low-shrinkage, coloured, exposed aggregate, post-tensioned slab grade): 5 – 7 working days. The plant needs lead time to source and trial the mix.
- Monday-morning pours are the most contested slot in the country — book 5 – 7 days out, not 48 hours.
Delivery slots and the 90-minute drum rule
Australian standards (and most batch plants’ own policy) require concrete to be placed within 90 minutes of being batched at the plant. The clock starts when the agitator drum first turns, not when the truck arrives on site. After 90 minutes the mix has lost workability, lost air content, and started to set — the supplier won’t warrant the strength, and they shouldn’t.
What that means for your sequencing:
- Plan a 60-minute unloading buffer. If the truck takes 30 minutes to get from plant to site, you’ve got 60 minutes from arrival to last barrow.
- Multi-truck pours need overlap, not back-to-back. Order the second truck to arrive 15 – 20 minutes before the first one is empty so there’s no cold joint.
- Don’t book the first truck for the start of placement — book it for the start of unloading. Crew should be on site 30 minutes earlier, not waiting for them.
- Site delays are your problem. Most suppliers allow 30 – 45 minutes free unloading; every extra 15 minutes is a $40 – $70 standing fee per truck.
Pump truck coordination
- Book the pump at the same time as the concrete, never as an afterthought.
- Confirm the pump is on site and primed 30 minutes before the first concrete truck arrives. Concrete waiting on a pump that’s late is the worst version of standing time.
- Order pump-grade slump (100 – 120 mm) when you book the mix — not when the truck arrives. Adding water on site is the single fastest way to destroy a slab’s strength.
- For boom pumps, walk the access in advance — overhead power lines, tree canopy and roof eaves all kill boom reach.
Slump testing on arrival
Every truck should arrive with a docket showing batch time, mix design and slump. On structural pours you (or the engineer’s inspector) should also run a slump test on the first truck — a standard cone, lift it, measure the slump. If it’s outside the spec (typically ±15 mm of the ordered slump), reject the load. The supplier replaces it. This is one of the few moments where saying “no” is cheaper than saying “yes”.
Cancellation and short-notice cost
Calling off a pour costs money. How much depends on when you call.
| When you call | Typical 2026 supplier charge | Why |
|---|---|---|
| Day before, before 4pm | $0 — $100 admin fee | Slot can usually be filled. |
| Day before, after 4pm | $150 — $400 | Plant has already sequenced trucks for the morning. |
| Pour-day morning before batching | $500 — $1,000 | Driver rostered; mix design loaded; truck washed and ready. |
| After truck has left plant | $1,000 — $1,500+ | You own the load — supplier dumps it as waste and bills you for it. |
| Truck on site, refused load | Full load price + return/dump fee ($150 – $400) | Only justified if the load fails slump/grade tests. |
The economics are obvious: a $200 – $400 day-before cancellation is cheap insurance against a $20,000 demolish-and-re-pour bill. Defer early, defer often, and don’t apologise for it.
Sequencing with formwork and reo crews
The pour is the last domino. Everything upstream — excavation, formwork, vapour barrier, reo, services — has to be signed off before the truck rolls. The sequence that consistently lands pours on schedule:
- Pour day minus 5: Confirm concrete order, pump booking, crew. Lock the BoM 7-day outlook check.
- Pour day minus 3: Excavation, sub-base, vapour barrier complete. Engineer/building inspector booked for reo inspection.
- Pour day minus 2: Formwork complete and braced. Reo placed, tied, chaired. Service penetrations (plumbing, electrical conduits) sleeved and signed off.
- Pour day minus 1, 10am: Engineer/building surveyor reo inspection. Any rework done same day.
- Pour day minus 1, 4pm: Run the go/no-go decision framework. Confirm or cancel.
- Pour day, T-60 min: Crew on site. Water and power tested. Curing compound, poly, hessian staged.
- Pour day, T-30 min: Pump on site and primed.
- Pour day, T-0: First truck unloads.
If you’re juggling this across multiple jobs at once, mobile-first scheduling matters — the foreman shouldn’t need to be at a desk to see whether tomorrow’s pour is on. The Built Simple platform for concreters and small builders is built around exactly this kind of tight, weather-sensitive sequencing.
Weather-aware scheduling in Built Simple
Built Simple’s scheduling module is built mobile-first because that’s where the decision actually happens — in the ute at 4pm the day before, not at a desk. Three things make it different for concrete work:
- Weather-aware tasks. Every scheduled pour task pulls the Bureau of Meteorology forecast for the site location and flags rain, frost or extreme-heat risk in the 24 hours after the planned start.
- Push alerts the day before. If the forecast shifts inside the 24-hour window, you get a notification before 4pm so you can run the go/no-go check while suppliers are still answering the phone.
- Drag-to-reschedule. Deferring a pour shouldn’t be a five-step process. Drag the task to the next clear day, the dependencies (pump, reo, crew calendar) move with it, and the affected contractors get an automatic update.
It’s the same logic this guide describes, automated — you still make the call, but the system has done the BoM check, the dependency reshuffle and the contractor notification before you finish your coffee.
Stop losing pours to weather
Built Simple’s weather-aware scheduling flags rain, heat and frost risk before pour day — built for Australian builders, mobile-first, no spreadsheets.
Common scheduling mistakes to avoid
- Trusting a 5-day forecast. BoM accuracy drops sharply past 72 hours. Lock the pour 24 – 48 hours out, not a week.
- Booking the truck for the start of placement. Book it for arrival — crew, pump and prep all need to be ready before the truck arrives.
- Pouring in marginal conditions to “save the cancellation fee”. The cancellation fee is always cheaper than a re-pour.
- Adding water on site. Order the right slump from the plant. Adding 25 L to a 6 m³ load can drop a slab from N32 to under N20.
- Skipping the day-before reo inspection. Trying to do it on pour morning either delays the truck or skips the inspection — both are bad outcomes.
- Not staging curing materials. Poly, hessian, curing compound and shade screens should be on site before the truck, not bought from the hardware store while finishers are screeding.
If you’re estimating a job, our Concrete Cost Calculator and Concrete Block Fill Calculator handle the volume and delivered cost in seconds — both are part of our free library of 50+ Australian trade calculators.
Frequently asked questions
What’s the ideal temperature to pour concrete in Australia?
The ideal pour temperature is 10 – 25°C air temperature, with curing temperatures around 21°C for optimal strength development. Below 5°C requires cold-weather mix and insulation blankets; above 32°C requires a retarder, a cold mix, and ideally an early-morning or evening pour to avoid the heat of the day.
Can you pour concrete if it’s going to rain?
No — if rain is forecast within the first 4 – 8 hours after placement, you should defer the pour. Fresh concrete is most vulnerable in that window: rain washes cement paste off the surface, weakens the top layer and causes scaling. Light rain 12 – 24 hours after placement is manageable with plastic sheeting and prompt finishing, but any heavier event in the first 8 hours warrants deferral.
How far in advance should I book a concrete truck in Australia?
Book residential pours under 10 m³ 24 – 48 hours ahead in metro Australia, pushing to 72 hours in peak season (October – March). Larger pours of 10 – 30 m³ need 3 – 5 working days. Specialty mixes (coloured, exposed aggregate, low-shrinkage, structural commercial) need 5 – 7 working days. Monday-morning slots book out first — lock them in a week ahead.
What’s the 90-minute drum rule for concrete delivery?
Australian standards require concrete to be placed within 90 minutes of being batched at the plant. The clock starts when the agitator drum first turns, not when the truck arrives on site. After 90 minutes the mix has lost workability and air content and started to set — the supplier won’t warrant the strength and you shouldn’t accept the load.
How much does it cost to cancel a concrete pour at short notice?
Cancellation fees scale with how late you call. Before 4pm the day before is usually $0 – $100. After 4pm the day before runs $150 – $400. Pour-day morning before batching is $500 – $1,000. Once the truck has left the plant you typically pay $1,000 – $1,500+ because the supplier has to dump the load as waste. Always defer before 4pm the day before if conditions are marginal.
Built for Aussie concreters
Built Simple is Australian construction project management software made for small and medium builders, tradies and owner-builders. Our scheduling, estimating and calculator tools are designed by builders, for builders — no spreadsheets, no signup walls. If concrete is part of your weekly mix, the Built Simple platform for concreters, the small builders platform, and our free Concrete Cost Calculator and Concrete Block Fill Calculator are built for you.
Calum Buchanan is the founder of Built Simple, based in Melbourne. Built Simple was founded in August 2025 to give Australian builders simple, mobile-first project management software. The thresholds in this guide align with AS 3600 and Cement Concrete & Aggregates Australia “Hot and Cold Weather Concreting” guidance and are intended as a general scheduling guide — always defer to the engineer’s specification and the batch plant’s mix-design advice for your specific pour.
