Reading a Set of Working Drawings: A Client's Guide

Most clients receive a drawing set, look at the plans, and approve it. The plans are the part that resembles a building, so they are the part that gets attention.

The plans are also the part least likely to contain the expensive mistake.

You do not need to read drawings the way an architect does. But you should be able to tell whether a set is complete, whether it is current, and whether it has been coordinated, because those three things determine what your building costs, and you are the only person with an incentive to check all three.

What is actually in a set

Architectural drawings. Site plan, floor plans, sections, elevations, and then the details, door and window schedules, toilet details, staircase details, finishes schedules, reflected ceiling plans. The plans are the summary. The details are the specification. A set with beautiful plans and thin details is not a complete set; it is a set that has deferred its decisions to the site.

Structural drawings. Foundation layout, column layout, beam and slab layouts, reinforcement details, schedules. You will not read these and you are not meant to. But you should confirm they exist for every level, and that the column grid on them matches the column grid on the architectural plans. It does not always.

Services drawings. Electrical, plumbing, HVAC, firefighting, and increasingly low-voltage and data as separate sets. These are where coordination lives and where coordination fails.

Schedules. Doors, windows, finishes, sanitaryware, ironmongery, light fittings. Unglamorous, and the single best predictor of whether a project will be priced accurately. A tender issued without schedules is a tender that will be re-priced later.

The title block tells you more than the drawing

Bottom right of every sheet. Read it before you read anything else.

• Drawing number: the sheet's identity. A set with gaps in the numbering has gaps.
• Revision number: which version this is. `Rev 0` is the first issue.
• Date.
• Status: the most important field on the sheet. `For Information`, `For Approval`, `For Tender` and `For Construction` are entirely different documents. Nobody should be building from a drawing marked `For Approval`. It happens constantly.
• Scale: and a note about whether the drawing may be scaled from. Usually it may not be. Written dimensions govern.

If a sheet arrives on site with no revision number or an unclear status, that is not a clerical problem. That is the beginning of a dispute.

The revision cloud

A cloud drawn around part of a drawing, usually with a small triangle carrying a revision number, marks what changed since the last issue. It exists so nobody has to compare two sheets line by line.

When you receive a revised drawing, look at the clouds first. If a drawing has been revised and nothing is clouded, ask why. Either nothing meaningful changed, in which case the reissue is unnecessary, or something changed and was not flagged, which is worse.

Coordination: the thing that is not on any single sheet

The most expensive failures in construction are not errors on a drawing. They are disagreements between drawings.

A beam where a duct needs to run. A column in the middle of a parking bay. A drainage line that has to cross a foundation. A false ceiling too shallow for the ductwork above it. Each of these is a perfectly correct drawing that contradicts another perfectly correct drawing.

They are found in one of two places: in a coordination review before construction, or by a foreman at nine in the morning with concrete arriving at eleven. The first costs a meeting. The second costs a change order and, often, a compromise you will live with for the life of the building.

The six questions

You can ask all six without being able to read a single drawing.

1. What is the status of this set? For Construction, or something less?
2. Are the schedules issued? Doors, windows, finishes, sanitaryware. If not, what is the contractor pricing?
3. Has this been coordinated against structure and services, and by whom? A name, not a reassurance.
4. Is the drawing register complete? Ask for the register, not the drawings, and look for gaps.
5. What is on site right now, and what revision is it? Not what was issued. What is physically in the site office.
6. What is still marked "to be confirmed"? Every TBC is a decision that has not been made, and it will be made later by whoever is standing closest to it.

The sixth is the one worth asking twice.