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Drawings show shape and position. Everything else the designer needs to say goes into notes: which standard the design follows, what the materials are, what loads it carries, how it is to be built. A coordinator who reads only the drawn views is reading half the instruction.
| Kind | Applies to | Typical content |
|---|---|---|
| General notes | The whole set or a discipline | Codes, materials, loads, tolerances, workmanship |
| Sheet notes | One sheet | Sequence, exceptions, references to other sheets |
| Keynotes | One element, by number | "Provide fire stopping", "Existing wall to remain" |
What general notes usually contain
- Design basis: the codes and standards the design follows, and the design life.
- Materials: concrete strength classes, reinforcement grade, steel grade, timber class.
- Loads: live loads, wind, snow, seismic category.
- Cover and tolerances: concrete cover to reinforcement, construction tolerances.
- Workmanship and sequence: welding, curing, stripping times, temporary works.
- Abbreviations and symbols not defined in the legend.
A note on a real sheet
Sheet 4 of the Benton Street Bridge (in the lesson on plans and sections) carries a note beside the girder details. In short: the girder flanges are joined to the web by two continuous shop welds made by an automatic process, flange splices are placed where stresses are no more than 75% of the full section, and at field splices the flanges are welded first, then the web. That is a sequence, a fabrication method and a design limit, none of which a 3D model of the girder would show.
The structural model shows the transfer slab with standard reinforcement. A general note on the drawings says "transfer slab: 50 mm additional cover for fire resistance". The MEP team sets cast-in sleeves from the model; on site, the sleeves clash with the top bars, which sit 50 mm lower than modelled.
During the model check, the coordinator reads the structural general notes and lists the ones that affect geometry: covers, chamfers, upstands, falls. The extra cover goes into the model, and the sleeves are set to the right level.
You find these five notes on a structural set. For each, say whether it should be in the model, in the specification only, or both, and why.
- "Concrete to slabs: strength class C32/40, exposure XC3."
- "Minimum cover to reinforcement: 40 mm."
- "Formwork to soffits not to be struck before 7 days."
- "All exposed edges: 20 × 20 mm chamfer."
- "Slab falls 1:80 to outlets."
Key takeaways
- General notes state the rules for the whole set: standards, materials, loads, tolerances, sequence and workmanship.
- Sheet notes and keynotes apply to one sheet or one element; general notes to all sheets they cover.
- Notes often carry requirements that never reach the model (welding method, splice positions, curing).
- When a note and a drawing seem to disagree, the contract's order of precedence decides; ask, don't choose.