Checking a fabrication drawing before approval

Approving a fabrication drawing means confirming that the workshop may make the item shown. It is not a casual acknowledgement that the drawing arrived. Once plate and sections are cut to an approved revision, a reversed hand, wrong level or missing joint becomes physical steel. Use this check for anything from a small frame to the made-to-measure work shown under steel structures.

Start with identity and revision

Read the title block before the geometry. Confirm project, item, drawing number, sheet count, date, revision letter or number and drawing status. A file name is not reliable revision control. If the PDF says preliminary, for comment or not for construction, do not treat it as the approval issue.

Put older versions in a clearly marked archive so that nobody can approve or install from them. When several drawings form one assembly, check that plans, elevations, details and schedules all carry compatible revisions. A changed plan with an old fixing detail is not a complete issue.

Confirm units, scale and view direction

Look for the stated unit, normally millimetres for European fabrication. Never assume that an unlabeled figure is millimetres, and never scale a missing dimension from a screen or printout. PDF printing, page fitting and photograph distortion make that value unreliable. Ask the drafter to add the dimension.

Identify each plan, elevation, section and detail. Arrows or section marks tell you which direction you are looking. Compare visible landmarks such as a wall, door, stair ascent or gate opening with site photographs. Handing errors happen when the drafter views from outside and the buyer describes from inside. State the reference explicitly, for example left hinged when viewed from the road.

Check overall dimensions against the site

Verify overall length, width and height first, then the dimensions that meet the building. Use a fresh site measurement rather than copying the value from your original enquiry. Confirm whether each figure goes to a finished face, structural face, centreline, edge, top or underside.

• For stairs, compare finished floor levels, opening, run and landing edges.
• For railings, compare post positions, slopes, corners and finished guarding height.
• For doors and partitions, compare finished opening at several heights and both diagonals.
• For gates, compare clear opening, ground levels, hinge side and travel envelope.
• For frames, compare grid lines, bearing levels and every connection interface.

Do not silently replace a drawing dimension with a handwritten value. Mark the conflict, give the measured value, its reference points and date, then ask for a revised drawing. Detailed measuring procedures for flights and landings are available under stairs and access.

Check levels, clearances and adjustment

Find every datum and level symbol. Confirm whether levels are finished-floor, structural slab or local workshop datums. Then check clearances around skirting, plaster, tile, glazing, moving leaves, drainage falls and maintenance access. A frame that fits the raw opening may not fit after lining.

Look for the intended adjustment: packing gaps, slotted holes, adjustable feet or site welds. Adjustment must be designed, not improvised. A welded assembly has fabrication tolerances and the building has construction tolerances. EN ISO 13920 provides general tolerance classes for welded constructions, but the drawing or project specification must state what actually applies.

Review supports, holes and anchors

Match every base plate, bracket and hole group to the real structural substrate. Render, plasterboard, floating screed, facing brick and deck boards are not adequate descriptions. The drawing should identify the support and show plate orientation, hole size, spacing, edge relationships and any stand-off through non-structural layers.

Do not approve a generic anchor note for an unknown wall. Fixings into concrete, brick, aerated block or timber are safety-critical. The structural engineer checks loads and substrate, while the selected anchor manufacturer's current assessment and installation data control drilling, embedment, spacing, edge distance and curing. Moving a hole on site requires design review, not a fitter's guess.

Check splits, assembly and the carry-in route

Locate every workshop weld, site bolt, removable panel and splice. Confirm which face receives bolt heads, whether tools can reach the joint and whether loose parts are identified. A connection hidden against a wall may be impossible to tighten. If a joint remains visible, confirm the appearance you expect.

Compare the largest assembled section with vehicle access, doors, corridors, stairs, lifts and turns. A product can fit its final room and still fail on the way there. If it cannot be carried in, ask for the split to be redesigned before approval. Do not assume the carrier or installer will cut a finished assembly.

Verify material and finish notes

Check section sizes, plate thicknesses, material designation where specified and every visible face. Confirm preparation and finish, including colour reference if powder coating is required. Any RAL colour choice needs the complete code and, where relevant, gloss or texture. Screen colours are not reliable samples.

For structural steelwork, the responsible designer decides whether EN 1090 execution requirements apply. A drawing reference does not prove a workshop's certification. Hot-dip galvanizing is specified under EN ISO 1461, while protective paint systems are selected with EN ISO 12944 and the exposure in mind. Vent and drain holes for galvanizing are functional and must not be deleted as cosmetic marks.

Use one controlled approval response

1. Print or digitally mark the current revision only.
2. Number each comment and point to the exact view or detail.
3. Separate required corrections from questions.
4. Return one consolidated response from all decision makers.
5. Request a clean revised issue and repeat the affected checks.
6. Approve by drawing number and revision, not by file name.

Do not approve subject to a long list of unresolved changes. That creates two competing definitions of the product. Either the drawing is correct, or it needs another revision.

Final sign-off record

Keep the signed issue with the order confirmation and your site survey. If supply of anchors, assembly instructions or delivery scope is not stated on the drawing, resolve it through the written order and the frequently asked questions before giving approval.