Job takeoff
Irrigation zone takeoff
Head count by spacing, head count by available flow, and the trench to get water there.
A takeoff is the trade word for the shopping list a job produces — every material, and how much of each, worked out by its own cited calculator.
- 7Measurements in
- 4Trades out
Give the job once
Every figure on the right follows these, in the units you choose.
Been given a quote for this job?
Paste it into the irrigation quote check: each line is read against these same calculators — what it leaves out, what it adds, and what to ask.
Check the quoteEvery trade, from those dimensions
then change a dimension, and each line shows what moved.
| Trade | Quantity | |
|---|---|---|
Sprinkler Head Spacing and Count CalculatorHeads the geometry needs, head-to-head at the default radius.
Why this quantity?
Resting on
Change any other figure on the Sprinkler Head Spacing and Count Calculator | 12 heads | |
Irrigation Zone CalculatorHeads the flow will actually run — set your measured flow on its own page, then compare.How this figure was reached
Resting on
| 5 heads per zone | |
Trench Excavation & Backfill Volume CalculatorThe trench above the sand, as loose fill with the calculator's compaction allowance: the whole void less a 25 mm (1 in) pipe and the sand zone. Where the dug soil goes back, as it usually does over a lateral, this is the volume to put back rather than material to buy.
Why this quantity?
Resting on
The loose-volume allowance: the calculator's working figure, a trade convention. Change any other figure on the Trench Excavation & Backfill Volume Calculator | 1.52 yd³ | |
Sand bed and cover round the pipeTrench Excavation & Backfill Volume CalculatorThe sand to buy: the trench width along the run, from the bed under the pipe to the cover over it, less the pipe, with the calculator's compaction allowance on it.
Why this quantity?
Resting on
The loose-volume allowance: the calculator's working figure, a trade convention. Change any other figure on the Trench Excavation & Backfill Volume Calculator | 1.1 yd³ | |
Sprinkler Head Spacing and Count CalculatorHeads the geometry needs, head-to-head at the default radius.
Why this quantity? | 12 heads | |
Irrigation Zone CalculatorHeads the flow will actually run — set your measured flow on its own page, then compare.How this figure was reached | 5 heads per zone | |
Trench Excavation & Backfill Volume CalculatorThe trench above the sand, as loose fill with the calculator's compaction allowance: the whole void less a 25 mm (1 in) pipe and the sand zone. Where the dug soil goes back, as it usually does over a lateral, this is the volume to put back rather than material to buy.
Why this quantity? | 1.21 m³ (loose) | |
Sand bed and cover round the pipeTrench Excavation & Backfill Volume CalculatorThe sand to buy: the trench width along the run, from the bed under the pipe to the cover over it, less the pipe, with the calculator's compaction allowance on it.
Why this quantity? | 0.8456 m³ (loose) |
Estimates, not a quote. Each row gives its base, the allowance on top, the adjusted figure and what to order; change an allowance on the row, or open its reasoning to see every figure it rests on. A trade's own page carries what it does not cover — open the one you are about to order against.
Labour and programme
Person-hours for the rows going in, from trade rules of thumb: a range for each piece of work, never a price.
- Trench Excavation & Backfill Volume7.9 h (4.4–18)
About 7.9 person-hours in the rows that carry them, between 4.4 and 18.
Trade by trade
- Labourer1 labourer1 day
About 1 day, one trade after another at eight hours a day. Left out: drying and curing, deliveries, inspections, trades overlapping.
3 rows carry no hours of their own
- Sprinkler Head Spacing and Count: no rate for its work here yet
- Irrigation Zone: a size or a check, not a piece of work
- Sand bed and cover round the pipe: no rate for its work here yet
Labour and programme
Person-hours for the rows going in, from trade rules of thumb: a range for each piece of work, never a price.
- Trench Excavation & Backfill Volume8.1 h (4.5–18)
About 8.1 person-hours in the rows that carry them, between 4.5 and 18.
Trade by trade
- Labourer1 labourer1 day
About 1 day, one trade after another at eight hours a day. Left out: drying and curing, deliveries, inspections, trades overlapping.
3 rows carry no hours of their own
- Sprinkler Head Spacing and Count: no rate for its work here yet
- Irrigation Zone: a size or a check, not a piece of work
- Sand bed and cover round the pipe: no rate for its work here yet
Setups you have saved
The build-up, the dimensions and any allowance you changed — kept on this device, and reusable on any job. Your prices are not copied in: they stay in your price book, so a setup never holds a stale one.
How far does a budget go?
At your own prices, with this build-up unchanged.
About this job
An irrigation zone is decided twice and the two answers have to be reconciled. Geometry says how many heads the area needs: sprinklers are laid out head-to-head, each one a radius from its neighbour so that its throw reaches the next head, and the count falls out of the radius and the pattern. Hydraulics says how many heads the supply can actually run at once: a zone is limited by the flow available, and asking eight heads to share the flow for five gives eight heads that all under-perform and none that fails visibly.
When the two disagree — and they usually do — the area is split into more zones rather than the heads being spread thinner. That is the decision this page exists to put in front of you, and it is not one either calculator can make on its own, because one of them has never heard of the other.
Head-to-head is not over-watering. The spray from a sprinkler is far heavier near the head than at its edge, so overlapping the throws is what produces an even application. A layout spaced wider than the radius — out towards the full diameter, where the throws only just touch — leaves dry rings between heads that show up in the first hot week.
How each line reads
- Base
- What the calculator gives for these dimensions, before anything is added.
- Allowance
- Cutting waste, a lap or spare stock — named, with where it comes from, and changeable on the row.
- Adjusted
- The base with its allowance on top.
- Order
- What to buy: the adjusted figure in whole boards, bags, rolls or lengths.
The order this happens in
Quantities do not tell you the sequence, and on this job the sequence is where the money goes wrong.
- Measure the available flow and pressure at the tap or the point of connection first. Everything else follows from it.
- Zone by what the planting needs, not by what is convenient — lawn and beds want different schedules.
- Lay the heads out head-to-head, squaring off the corners of the zone.
- Check the head count against the zone's flow, and split the zone if it exceeds it.
- Trench deep enough to be below anything that will dig, and bed the pipe on sand.
- Flush the lines before fitting the nozzles, then run each zone and adjust the arcs.
What this takeoff does not cover
- The controller, valves, backflow prevention and the point of connection.
- Pipe sizing, which follows flow and run length rather than the zone's area.
- Pressure loss along the run, and whether the last head still performs.
- Winterisation, which in a freezing climate decides how the whole system is laid out.
- Drip irrigation for beds, which is a different system with a different layout rule.
Quote check
Been given a quote for this job?
Paste it into the irrigation quote check. Every line of it is read against these same calculators and your measurements. Quantities only, never prices.
What it leaves out
Every line this takeoff has that nothing on the quote reads as.
What it adds
Labour, removal, hire, fees — each named for what it is.
What to ask
One list of questions, ready to copy. Never a verdict.
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Frequently asked questions
- What does the irrigation takeoff give for a typical job?
- Opened at Zone length 12 m · Zone width 8 m · Trench run 30 m · Trench depth 0.3 m · Trench width 0.2 m · Sand bed under the pipe 0.05 m · Sand cover over the pipe 0.05 m, it orders: Sprinkler Head Spacing and Count, 12 heads; Irrigation Zone, 5 heads per zone; Trench Excavation & Backfill Volume, 1.21 m³ (loose); Sand bed and cover round the pipe, 0.85 m³ (loose). Opened at Zone length 39 ft · Zone width 26 ft · Trench run 98 ft · Trench depth 11.8 in · Trench width 7.75 in · Sand bed under the pipe 2 in · Sand cover over the pipe 2 in: Sprinkler Head Spacing and Count, 12 heads; Irrigation Zone, 5 heads per zone; Trench Excavation & Backfill Volume, 1.52 yd³; Sand bed and cover round the pipe, 1.1 yd³. Every figure follows the dimensions you give it.
- Which calculators does the irrigation takeoff run?
- 3 calculators, for 4 lines: Sprinkler Head Spacing and Count Calculator, Irrigation Zone Calculator, Trench Excavation & Backfill Volume Calculator. Each has a page of its own with its formula and its sources; the takeoff runs them all on one set of dimensions.
- What does the irrigation takeoff leave out?
- 5 things, each named on this page: The controller, valves, backflow prevention and the point of connection; Pipe sizing, which follows flow and run length rather than the zone's area; Pressure loss along the run, and whether the last head still performs; Winterisation, which in a freezing climate decides how the whole system is laid out; Drip irrigation for beds, which is a different system with a different layout rule.
- Can I check a quote for this job against the takeoff?
- Yes. The irrigation quote check reads a quote's lines against these same calculators and your measurements, and reports what it leaves out, what it adds and what to ask. It reads quantities, never prices.