Quoting from architects' drawings: a builder's reading list

A drawing set is not a picture of a building, it is a legal description of one, and the price hides in different corners of it than the eye is drawn to. Here is the order an estimator reads a set in, what to trust, and where the money buries itself in the small print.

Know what you have been sent

First, establish what kind of set this is, because it sets your risk level before you read a line. Planning drawings exist to win permission: pretty elevations, minimal construction detail, often no structure at all. Building regulations drawings exist to satisfy building control: construction build-ups, insulation specs, drainage. Construction or tender drawings, if you are lucky enough to get them, exist to be built from and priced against.

Pricing a fixed sum from planning drawings alone is gambling with your margin, because everything that costs real money, foundations, steel, build-ups, services, has not been decided yet. You can still quote, but the quote must say what it is based on and carry allowances for what is missing. Note the revision letter on every sheet too, and confirm you hold the latest set; pricing revision B when revision D exists is a classic self-inflicted wound, and worth a line in your assumptions either way.

A reading order that catches the money

Do not start with the floor plan, tempting as it is. An estimator's pass through a domestic set runs in this order:

1. Title blocks and notes, every sheet. Scale, revision, and the general notes where phrases like "contractor to allow for" live. Those five words are instructions to price something that appears nowhere else.
2. Sections. The section tells you heights, build-ups, floor construction, roof construction and insulation, which is most of the specification in one drawing.
3. The structural engineer's drawings and calcs, if they exist. Steels, padstones, foundation depths. If they do not exist yet, that is a provisional sum, not a guess.
4. Plans. Now measure: areas, wall lengths, openings, drainage runs. The plan is for quantities, not for understanding the job.
5. Elevations. Materials, external details, and the questions: what is that cladding, who prices the chimney repair that is drawn but never mentioned?
6. The specification document, if provided, read against the drawings for contradictions, because when spec and drawing disagree, that is a written question to the architect, today.

Scales, dimensions and what to trust

The rule drummed into every trainee QS applies doubly to builders pricing from PDFs: written dimensions beat scaled dimensions, always. Architects write the dimensions they have checked; everything else on the sheet is drawn approximately to scale and printed at whatever size the client's printer fancied. A PDF printed "fit to page" is no longer 1:50, and measuring it with a scale rule prices a building 6 percent smaller than the real one.

So: use written dimensions first, check the scale bar if you must scale, and verify one known dimension, a door width is ideal, before trusting anything measured off a print. Where a dimension you need does not exist, ask for it in writing rather than deriving it from three others, and cross-check the critical ones on site as part of your site survey: existing buildings have a habit of disagreeing with the drawings of them.

Specs and notes: where the cost hides

Two drawings of the same extension can carry a 30 percent price difference entirely in the annotations. The items that move money most, and are easiest to skim past:

• Named products. A note that says "grey aluminium bifold" and one that names a premium system differ by thousands. Named product means price the named product or formally offer an equal-and-approved alternative.
• Build-up depths. Insulation thicknesses, screed depths and acoustic layers set your material quantities and your floor levels. A 150mm insulated slab and a 100mm one are different jobs.
• The drawn-but-not-listed. Rooflights that appear only on the elevation, the retaining wall implied by the site levels, the rainwater harvesting shown with a dotted line. If it is drawn anywhere, someone expects it priced.
• Performance clauses. "Achieve airtightness of..." or "all to current Building Regulations" can carry testing, membranes and detailing time that never appears as a drawn object.

From drawings to quantities to a price

Once the set is understood, the take-off is mechanical: work element by element, substructure to decoration, measuring areas, lengths and counts into a structured list, then rate each line. That structured list is a bill of quantities, and building one from drawings is the most time-consuming honest way to price, an evening or two per job by hand.

It is also, increasingly, the part a machine does well. QS Quoter reads the drawing set you upload, does the take-off, and returns a full bill priced at your own rates on a calibrated 2026 UK rate book, every line editable before it goes anywhere near the client. Your judgement still owns the questions above, the revision check, the named products, the notes; the measuring and typing stop costing you your evenings. And when the drawings are thin, quote what is drawn, exclude what is not, and put provisional sums against the gaps, loudly and in writing.