Quote vs drawings: check the quantities before you sign
Most quote checks stop at the rate and the total. The rate looks fair, the total sits near the other quotes, and the subcontract gets signed. The quantity under each line rarely gets checked. That is where the margin goes missing.
The drawings in this post are samples we made for illustration, not a real project.
Quick answer: to check quote quantities, measure every length, count and area off the drawings yourself, then set your figure beside the quoted one, line by line. Flag anything short, missing or doubled. In our 12-line sample drainage check, 9 lines did not match the drawings, and a 36.5 m subsoil drain was not priced at all.
Why the total is the wrong place to start
Every priced line is a quantity times a rate. If the quantity is short, the line is short, however fair the rate. A good rate on 96.0 m of pipe does not pay for 118.4 m of pipe.
The gap does not disappear when you sign. Where it lands depends on the subcontract:
Lump sum to the drawings. On paper the subbie carries the missing metres. In practice, a subbie who missed scope may claim a variation, argue it, or try to recover it elsewhere.
Schedule of rates with remeasure. The extra metres come back to you at the quoted rate, after your own price is fixed.
Either way, someone pays for 22.4 m of stormwater pipe that nobody priced.
The sample: a 12-line drainage quote
Here is a sample drainage package for a residential lot. Twelve lines, quantities only, no rates.
Sample: the quote as received, 12 lines of quantities with the measured column still to be filled in.
On a quick read nothing looks wrong: 96.0 m of 150 stormwater pipe, 64.0 m of 100 wastewater pipe, 3 manholes, 4 cesspits, 160.0 m of trench.
Then there is line D-10, the 110 slotted subsoil drain, marked NIL. NIL means the item is on the quote with no quantity against it. Someone saw it, and nobody priced it.
What the drawings said
Now the same 12 lines, measured off the drawings.
Sample: the same 12 lines measured off the drawings. 7 under-quoted, 1 over-quoted, 1 missing.
Nine of the 12 lines don't match:
7 under-quoted. Stormwater pipe 96.0 m quoted, 118.4 m measured (+22.4 m). Manholes 3 against 4. Cesspits 4 against 6. Trench 160.0 m against 179.9 m. Bedding 38.4 m³ against 43.2 m³. Encasement under the drive 6.0 m against 9.5 m. Asphalt reinstatement 12.0 m² against 18.6 m².
1 over-quoted. Wastewater pipe 64.0 m quoted, 61.5 m measured (−2.5 m).
1 missing. Subsoil drain NIL quoted, 36.5 m measured.
3 matched. Downpipe connections (8), inspection points and rodding eyes (7), connection to the public main (1).
One short run moves three lines
The trench line is the two pipe lines added together. Quoted, 96.0 + 64.0 = 160.0 m. Measured, 118.4 + 61.5 = 179.9 m. The bedding follows the trench, from 38.4 m³ to 43.2 m³.
So one short stormwater run leaves the pipe, the trench and the bedding short at once. When you find one short length, check every line built from it.
The missing line is the one that hurts
A short line still has a price on it. A NIL line has nothing: no pipe, no labour, no allowance. In the sample, 36.5 m of subsoil drain sits on the drawings with no price against it. It is the biggest gap on the sheet.
If the subbie meant to leave it out, it belongs in the written exclusions and you need a price for it before you sign. If they missed it, get that answered in writing now, not when the drain is being laid.
How to check quote quantities in four steps
Sample: the four steps, using the stormwater pipe line (quoted 96.0 m, drawn 118.4 m).
Drawings in. The plans, the specification and the quote you were given. Check the quote names the drawing revision you hold. A quote priced off an older revision can be wrong on every line.
Measure. Take every length, count and area off the drawings before you look at the quoted figures. If you read 96.0 m first, 96.0 m is what you will tend to find.
Compare to the quote. Line by line, what was priced against what is drawn. Line D-01: quoted 96.0 m, drawn 118.4 m.
Flag the gaps. Short, missing or doubled-up items, in plain numbers: +22.4 m under-quoted, NIL to 36.5 m missing. An item priced twice, or by two trades, is paid for twice.
Then send the flags back as questions, in writing, before you sign: "Your quote carries 96.0 m of stormwater pipe. We measure 118.4 m. Please confirm or re-price." Put the answers into the subcontract.
When the quote runs to 68 lines, not 12
Our sample electrical bill of materials for a 4-bed new build runs to 68 lines across 13 sections.
Sample: two sections of a 68-line electrical bill of materials for a 4-bed new build.
The cable section alone is 8 lines, including 420 m of 1.5 mm² twin and earth for lighting and 560 m of 2.5 mm² for power. The TPS lines total 1,226 m.
Two lessons carry over:
Every quantity needs its own numbered line and unit. You can check 560 m of 2.5 mm² twin and earth. You cannot check "cabling as per drawings".
Long bills give lines more places to slip. Check all 68 lines, not just the big-dollar ones.
If a subcontract quote arrives as a lump sum with no quantities, ask for the quantity schedule behind it. In one published roofing quote with two conflicting materials lists, the insulation quantity covered roughly 5% of the ceiling area.
If you're the subbie checking your own takeoff
Run the same check before your quote goes out. In the sample, the 7 under-quoted lines would come out of the subbie's margin on a lump sum, and the 36.5 m NIL line would become an argument on site. The over-quoted wastewater line, 64.0 m against 61.5 m, costs nothing on site but lifts your price when you are competing.
If you'd rather hand the measuring over, we can produce the takeoff or verify yours.
Next step: Takeoff Verification or the free quote check
Takeoff Verification: $490 + GST per trade, back in 48 hours. We re-measure the quantities off your drawings and mark each line confirmed or out, in writing, with a marked-up drawing set. How Takeoff Verification works.
Free quote check. Send the drawings and 1 quote. We check it line by line and send the gaps back in writing, each tied to the drawing it came from.
Several subbie quotes at once? See quote review for builders.
Both start at trueworks.co.nz/contact.
FAQ
How do I check quote quantities if I'm not confident reading drawings?
Start with counts. Manholes, sumps and downpipe connections are symbols you can count on the plan. In the sample, counting alone shows the quote 1 manhole and 2 cesspits short.
Should a subcontract quote show quantities?
Ask for them. A quote with a quantity and unit on every line can be checked in writing. A lump sum "as per drawings" can't be checked until the subbie shows the quantities behind it.
What if a quote is over, not under?
Flag it too. In the sample, wastewater pipe was quoted at 64.0 m against 61.5 m drawn. That means paying for pipe that isn't drawn, or a quote priced off a different revision. Either way, ask.
How much does a quantity check cost, and how long does it take?
Takeoff Verification is $490 + GST per trade and comes back in 48 hours. Or start with the free quote check.
Before you sign the next subcontract quote, check the quantities, not just the total. Send the drawings and the quote through trueworks.co.nz/contact and we'll check it line by line, in writing. Your first one is the free quote check: no charge, NDA available.
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