Drawing revision control on site
Why a gang ends up building from a superseded drawing, and the six rules that stop it. Written by a steel detailing office that has issued a lot of revisions.
How it goes wrong
A drawing is issued as P01, checked, and reissued as C01. Then the engineer moves a bolt group and it goes out again as C02. Each issue is right at the moment it leaves the office. The trouble starts in the next hour.
C01 went to site by email, and the foreman saved it to his phone. C02 went to the same email thread, and to the WhatsApp group, and to the client. On the phone, C01 and C02 now sit side by side with nearly the same name. The register in the office says C02 is current; nothing on the phone says C01 is not. Someone opens the wrong one, because it is the one they opened last week. The steel is fabricated to C02 and set out to C01, and the difference is found on a Friday afternoon with a crane on hire.
Nobody in that chain was careless. The system asked a person to remember which of two near-identical files was dead, and people do not remember that.
Six rules
- The drawing number is the identity. A revision replaces the previous one under the same number. A different number is a different drawing, however similar. Never reuse a number, and never let two drawings carry one.
- One revision of a number is current, and it is obvious which. Wherever a drawing lives, the superseded one is marked so that it cannot be mistaken: a stamp across the sheet, a status beside the row, a name that says so. If telling them apart takes a register lookup, site will not do it.
- Supersede, do not delete. The old revision is a record: what was issued, when, to whom. Keep it, mark it, move it out of the way.
- Issue once, to one place. A drawing that went out by three routes has three lives. Site should have one place to look, and everything it holds should be current or plainly marked as not.
- Tell people when it changes, not when they ask. A revision that lands silently is a revision that gets missed. The person on site should be told the moment C02 replaces C01, on the thing in their hand.
- The register is a record, not a plan. Fill it from the title block at the moment of issue, never from memory later. If the register and the drawings can drift apart, they will.
What this means for the office
Most of the rules are about the office's habits, not site's. The office decides what goes out, by which route, and whether the old sheet is marked. A register kept in Excel can follow all six rules if one person keeps it religiously; the template on this page is laid out for it. The weak point is the word "religiously": the rules hold until the week two jobs issue on the same day.
What Drawing Inbox does with these rules. The office drops the approved drawing into a box on the PC. It reads the title block, files the sheet under its number (rule 1), marks the previous revision superseded and stamps it (rules 2 and 3), keeps history (rule 3), is the one place site looks (rule 4), tells the site team's phones the moment a revision lands (rule 5), and fills the register from the sheet itself (rule 6). A drawing forwarded from a phone goes as the file, never a link. PDF, DWG, DXF and IFC. £49 a month per company, plus VAT.
Drawing Inbox is made by M&R Tekla Detailing Limited, a steel detailing office in Okehampton, Devon. Questions: hello@drawinginbox.com.