Metalwork brief checklist

At a glance

The numbers match the balloons on the annotated drawing. 'If missing, expect' describes the usual consequence of a gap, not a certainty: it is the studio's reading and has not been checked with fabricators.

The drawing is the brief

A metalwork drawing is read by someone pricing the job, then by someone cutting and welding it, and then by someone checking it. None of them is in the room when you decide what you meant. Whatever the drawing does not say becomes a question, an assumption or an allowance in the price, so the aim is to put the decisions on the sheet, once, in words that have one meaning.

This sheet is for the design-intent drawing and specification you issue. The pack that goes out with it is covered in our request for quotation pack, and the drawing the fabricator sends back is checked with our shop drawing approval checklist. The twelve items below are the points where a metalwork drawing most often leaves a decision open. They are our own list, drawn from the standards and guides named below and from our sheets on finishes, welds and samples, not a published standard.

Twelve items on an invented panel

The drawing shows a stainless panel with a brass inlay, a welded return and hidden fixings. The panel is invented, and every value in the title block is an example. The numbers match the table at the top of the page.

• Items 2 and 3. Name the metal by its standard designation, and the thickness in millimetres. A gauge number is not a thickness: see our sheet thickness and gauge page. Ask for a batch test certificate only where you need to prove what the metal is; EN 10204:2004 sets out the types of inspection document, and 3.1 is the one usually asked for. Confirm what each type means against the standard.
• Items 4 and 6. Say where each dimension comes from. A dimension taken from a drawing and one measured on site are different promises: see the site survey sheet. Give an individual tolerance where parts must fit or line up, such as the gap round a brass inlay, and let the general tolerance cover the rest.
• Item 9. Mark which faces are seen. A finish, a weld dressing or a polish on a face nobody sees is effort spent where no one looks. Coating standards call the area that matters a significant surface, and the term is worth borrowing.
• Items 11 and 12. The signed sample is the standard for appearance: see sample approval and batch variation. Protective film, packing and marking are quick to specify and hard to put right once a piece is damaged on site; see the delivery access survey for the route.

Tolerances: one general class, a few specific ones

EN ISO 13920:2023 gives general tolerances for welded constructions: for lengths and angles, and for shape and position, in four classes it describes as based on customary workshop accuracy. The class is chosen mainly by function. The part of the standard worth knowing as a specifier is the rule about drawings: a drawing that gives dimensions or shape and position indications without individual tolerances is deemed incomplete if it has no, or an inadequate, reference to general tolerances. We read this from the standards-database listing; the class values are in the standard, which we did not read, so none are quoted here.

• State the class once, in the drawing notes, so that every dimension without its own tolerance is covered. Ask the fabricator which class it works to.
• Add individual tolerances sparingly. Use them where something must fit or align. A tolerance tighter than the function needs can add checking and rejection, and the fabricator may price for it.
• Machined and non-welded parts may call for a different general-tolerance reference. BSI's listing for BS 8888:2025, the technical drawing standard, says it has a new section on general tolerances referring to ISO 22081, with updated guidance on ISO 2768-1. We did not read the text. For furniture and joinery tolerances see our furniture and joinery sheets.

Finish and welds: point to the page, then to the sample

Words like brushed, satin and polished do not define a finish. Name stainless by its EN code or an approved sample, with a roughness and a grain direction: see stainless finish codes. For plated, lacquered or PVD finishes say which and, where it matters, how thick: see plating and coating thickness. For paint, name the colour reference, the gloss in gloss units and the texture: see RAL, BS 4800 and NCS and our powder coating sheet. Say whether the finish is applied before fabrication or after it, because a weld, a bend or a polish changes the surface beneath.

For welds, pick a rung of the ladder in our weld finish sheet and mark it where it applies. EN ISO 5817 grades the imperfections a weld may have; it does not describe how a finished weld looks, so a quality level is not a finish.

Say how a finish will be judged. One scheme we read, Qualisteelcoat for coatings on steel, inspects coated parts at 3 m for an interior and 5 m for an exterior, in diffuse daylight with the naked eye. That is its rule for its own tests, not a general one, but it is the kind of sentence a drawing note can copy: distance, light, and who looks.

Fixings, evidence and what to leave to the fabricator

Fixings are where a brief most often goes quiet. Name the material, the head and drive, whether they show, and what they fix into, and say how they are kept from touching a different metal: see galvanic corrosion and dissimilar metals. Welds are shown on a drawing by symbols: EN ISO 2553:2019 is the standard for welding symbols on drawings, which we know from its listing only.

Leave to the fabricator what is theirs to decide: the construction, the weld process and sequence, and the shop drawing. Ask them, before they price, to list any assumption they have made about material, finish, tolerance, welds, fixings or quantities that is not on your drawings. Compare the lists. Our sheet on why quotes differ shows what the differences mean.

Metal: [316 stainless steel, EN 1.4404], [sheet], [2.0] mm finished thickness. Certificate: [EN 10204 3.1]. Dimensions are finished sizes from [datum]. General tolerances: [EN ISO 13920, class [ ]] for welded assemblies, [ ] for other parts; critical dimensions are marked [ ]. Welds as scheduled, [ground flush and refinished] on faces marked [V]. Finish: [EN 10088-2 2J, Ra not more than [ ] um, grain vertical].

Faces marked [V] are visible and are judged at [3] m in [diffuse daylight] by [the designer]. Control sample [S-01], signed [date], is the standard for appearance; limit samples [S-02, S-03] mark the range. Protective film to remain until [fixing]. Parts marked [ ] and packed [ ].

Before pricing, the fabricator is to list every assumption about material, finish, tolerance class, weld finish and quality level, fixings, certificates, packing or quantities that is not shown on these drawings, and to state the general tolerance class and weld quality level it will work to.

Standards and sources

• EN ISO 13920:2023, Welding: general tolerances for welded constructions: listing read only.
• BS EN 10204:2004, Metallic products: types of inspection documents: listing read only.
• BS 8888:2025, Technical product documentation and specification: listing read only.
• EN ISO 2553:2019, Welding symbols on drawings: listings only.
• Qualisteelcoat Technical Specifications 5.0.1 (valid 1 January 2026), section 6.13: viewing distances for coated parts.

Questions we are asked

What tolerance should I put on a metalwork drawing?

Name one general tolerance reference for every dimension without its own, and add individual tolerances only where parts fit or line up. For welded constructions the reference is EN ISO 13920 and a class; the class values are in the standard, so ask the fabricator which class it works to. The standard treats a drawing with no general-tolerance reference as incomplete.

Do I need a 3.1 certificate?

Ask for one where you need to prove what the metal is, such as structural parts, or where a client or the specification requires traceability. EN 10204:2004 sets out the types of inspection document, and 3.1 is the usual request. Check the definitions in the standard and ask the fabricator what it can supply.

How should I describe a stainless finish?

By its EN 10088-2 code or an approved sample, with a roughness and a grain direction. Brushed and satin do not define a finish. See our stainless finish codes sheet, and approve a welded sample as well as a flat one.

Should I specify the welding process?

Usually not. Specify the result: where each weld is, its finish and, where it is to be inspected, its quality level. Leave the process and sequence to the fabricator, and ask for them on the shop drawing.

What is the difference between this and a shop drawing?

This is the design-intent drawing and specification you issue. A shop drawing is the fabricator's drawing of how it will build the piece, which you check before releasing production. See our shop drawing approval checklist.