06 · Estimating
A $240,454 roofing bid, sealed in under 19 minutes
18 min 27 s from 284 pages of plans and specs to a sealed bid, every line priced
What it does
I built an estimating machine that reads a public roofing bid package, builds the roof in 3D from the drawings, prices every line from a basis frozen before any total existed, and seals its number before it sees a competing bid. Its first run left base-bid work off the estimate, so I added a check that stops any run before pricing when required work has no line. The sealed Las Positas College bid came to $240,454.
What I built
- A fresh, walled-off reader for each run that reads the bid documents
- A 3D roof built from the drawings, with every quantity measured from it
- Pricing for every line from a basis frozen before any total existed: the wage determination, tax, supplier pages and rental rates
- A scope check: anything the documents put in the base bid lands on a priced line or a written question, or the run stops before pricing
- A bid package (the estimate, the filled bid form and questions for the owner), sealed with a hash
- The Bid Workbench app: click a line to light its geometry and source sheet, or change hours and prices live
The record
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Las Positas College, sealed: base bid $210,454, total $240,454, at 03:32:10 UTC on 2026-10-05
Seal record, Las Positas
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The machine read 5 public files, 284 pages: the ad (2), the addendum (3), the bid book (225), the drawings (5) and the specs (49)
Machine inputs, Las Positas
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The total is the base $210,454 plus the college's $30,000 allowance, the same basis the bid tab uses
Narration notes
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The roof: 111' x 56' = 6,216 SF with a 334 LF perimeter, and all 19 items sit on their drawn symbols when projected back onto sheet A-2
Run notes
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The first run read the documents right, but the estimate had no line for work they put in the base bid; on the re-run with the check, all 14 base-bid requirements landed on a priced line or a written assumption
Run notes
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Sealed 18 min 27 s after the run started (03:13:43Z to 03:32:10Z)
Project notes
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Audit: 157 calls, no violations; the machine matched the frozen commit byte for byte
Run notes
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Union City Library, sealed: base bid $137,409
Seal record, Union City
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The sealed Las Positas bid landed inside the range of the nine real bids for the same job
Comparison notes
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Line costs in the sealed estimate: tear-off $15,687, polyiso insulation $13,951, cover board $13,016, membrane $25,279, perimeter edge metal $8,951
Sealed estimate
Honest frame
Both jobs were past public bids with published results, and nothing went to any owner. I already knew what the companies bid, since bid tabs are public, so the machine never got them. It was fixed after its dev runs and frozen before any total existed. No estimator has reviewed it yet.