At a glance
| What is limited | Who controls it | What to write | Number from, and the sheet |
|---|---|---|---|
| Made: sizes, squareness, flatness, height | Workshop | ± mm by size band, at a stated humidity; the method drawn | Agree with the workshop; no UK furniture standard we read gives figures. Furniture tolerances |
| Made: welded or fabricated metal | Fabricator | A named standard class and edition; a drawing figure governs | BS EN ISO 13920:2023 (welded); BS EN 22768-1:1993 (machined, sheet-formed). Values not read. Visible metalwork |
| Made: doors, stone, board, sheet | Supplier or workshop | The product standard and edition, allowed for in the build-up | Named, not read. Doors, stone, boards |
| Built: walls, floors, ceilings | Main contractor | The limits you assume, to one datum, then a survey | LABC Warranty, Version 11 (2022): walls flat ±3 mm on 2 m, 8 mm from plumb to 3 m; floors flat ±5 mm on 2 m, level 3 mm per metre to 6 m. Scribing |
| Between: scribe and filler | Designer, by detail | A margin in mm at each end, from the survey | Arithmetic from the survey, not a standard |
| Between: shadow, door and drawer gaps | Workshop and installer | Width, evenness, method, judged on a mock-up | No standard we read gives one. Shadow gaps |
| Moves: timber, veneer, upholstery, floors | No one: design for it | The conditions the numbers apply at | Timber movement |
Figures appear only where a document read for this sheet gives them; the rest is ‘agree with the workshop’. Warranty acceptance levels are not design tolerances, and LABC Warranty now lists Version 13 (quotes from 1 January 2026), not read in full.
Three places a tolerance can live
A bespoke item meets a building in three places, and a different party controls the variation at each. Write one number for each place, not one number for all of them.
- Made. The workshop controls the size, squareness, flatness and finish of the piece. The number goes on the shop drawing with a datum and a way of measuring it.
- Built. The main contractor controls the walls, floors, ceilings and openings the piece goes into. You cannot specify them out of the way. You can state the limits you have assumed, survey to test them, and say who corrects anything outside them.
- Between. The designer controls the gap between the two, by detail: a scribe strip, a filler, a shadow gap, adjustable feet. This is where made and built are reconciled, and it is only as wide as the drawing makes it.
A fourth source of variation belongs to no one: timber, veneer, upholstery and floors move after handover. That is not a tolerance but a condition the tolerances apply at. Our furniture tolerances sheet keeps tolerance, limit and movement apart; this sheet is about writing them into a specification, and joinery tolerances and scribing deals with the building side.
BSI describes BS 5606:2022, Accuracy and tolerance in design and construction, as a guide for setting a project strategy for accuracy and tolerance: assess what a design needs, specify to suit, assess whether the tolerances are likely to be achieved, then monitor and verify, including the accuracy of surveys. It treats accuracy and tolerance as separate characteristics, and keeps its 1970s and 1980s tables of industry performance only for historical reference. We have not read the standard. The order it describes is the order of the schedule below.
Which number governs when two disagree
People seldom dispute a number that is written down. They dispute which of several numbers applies. Put an order in the specification and use it.
| Order | Source of the number | What to know about it |
|---|---|---|
| 1 | The tolerance written on the approved shop drawing | It governs everything below. BSI’s scope text for BS EN ISO 13920:2023 says the applicable tolerances are always those stated in the drawing, and that manufacturing documentation giving sizes with no tolerance, and no adequate reference to general tolerances, is incomplete. |
| 2 | A class from a named standard, with its edition | For dimensions that carry no tolerance of their own. BS EN ISO 13920:2023 gives four classes for welded constructions. BS EN 22768-1:1993 gives four for machined or sheet-formed parts, and applies only to dimensions with no individual tolerance. Name the class and the edition. |
| 3 | The workshop’s declared capability for the process | Ask for it before the tender, in millimetres, by process and size. It is what the workshop will price against. Nothing on this sheet states what any partner workshop holds. |
| 4 | A scheme’s acceptance levels | A warranty manual states what it will accept on a claim. LABC Warranty’s manual says it measures only the tolerances it identifies, and that a more stringent tolerance may be stated in a standard. Its figures describe new homes and are not design tolerances. |
| 5 | ‘Normal’ or ‘usual’ practice | No one can enforce it. Replace it with a number or with an approved sample. |
Contracts rank their own documents too, and the contract’s order of precedence may differ from this one. Ask the contract administrator, and write the same order into your schedule.
The tolerance schedule: one line for each tolerance
A schedule is a table that sits with the specification and the shop drawings. Each line answers seven questions, so that two people measuring the same thing get the same answer.
- Ref and what. A prefix says whose line it is: M for made, B for built, G for the gap between.
- Datum and method. Where it is measured from and with what: finished floor level, a straightedge of a stated length, the two diagonals, a gap gauge. The furniture sheet draws three of these methods.
- Tolerance. Plus and minus, or one-sided. Where a regulation caps a dimension, set the nominal inside the limit by the whole tolerance (also on the furniture sheet).
- Checked by, and when. The party and the hold point, as in the table further down.
- Number from. The shop drawing, the survey, a standard with its edition. Naming the basis stops a warranty acceptance level being mistaken for a design tolerance.
- If outside. Rework, replace, notify before fabrication, or accept by a recorded concession.
Keep the B lines apart from the M lines. A workshop answers for what it makes; it cannot answer for a wall it was told to assume.
Adding up at the gap
The three kinds of variation meet in the gap, so the gap has to be able to absorb their sum, or the sum has to be made smaller. The arithmetic is simple and worth writing on the drawing. The table uses invented values for a run of panelling against a wall.
| What adds to the variation at the gap | Example (mm) | Who controls it |
|---|---|---|
| Survey accuracy: how closely the opening was measured | ±[2] | The surveyor |
| Change after the survey: finishes and floor build-up still to come | ±[3] | The main contractor |
| The unit as made, to its tolerance | ±[2] | The workshop |
| Setting out and fitting on site | ±[2] | The installer |
| Worst case at one side, all at their limits | ±[9] | Added: our arithmetic, invented values |
A shadow gap drawn at [10] mm that has to read as even cannot absorb a swing of [9] mm. Either the detail hides the variation (a scribe, a cover strip, a deeper reveal) or one of the four lines is tightened and checked. Which line is cheapest to tighten is a question for the workshop and the installer, not a number we can give. Statistical sums exist, but a flush joint should not rely on them (see the furniture sheet).
Why veneer, stone and metal do not share one number
The same word means different things in different materials, so one general figure is wrong for most of them. The table says what drives the variation and what to write. It gives no figures: where a figure exists, it is on the sheet in the last column.
| Material | What drives the variation | What to write | Sheet |
|---|---|---|---|
| Solid timber and veneer | Moisture: the size changes with humidity after the piece is made. Match and figure are judged by eye. | The moisture content at manufacture and the room conditions the tolerances apply at; a sample for match. | Timber movement; veneer |
| Natural stone | The product standard for the product and finish sets a thickness tolerance, and the joint width follows it. | The standard and its edition. Our stone sheet names BS EN 12057 (modular tiles) and BS EN 12058 (slabs for floors and stairs) and quotes no figure; neither was read for this sheet. | Stone specification |
| Metal | Welding distorts, sheet is never exactly its nominal thickness, and metal expands with heat. | A class for welded work; the product standard’s thickness tolerance for sheet; an allowance for thermal movement. | Welds; sheet; expansion |
| Upholstery and soft pieces | Padding compresses and stitching moves, so a firm-edge figure does not carry over. | A wider band, set as sat on or at a stated point. | Seat dimensions |
When each tolerance is checked, and by whom
A tolerance nobody checks is a wish. Tie each line of the schedule to a hold point, the party who measures, the instrument, and the place the reading is recorded.
| Hold point | What is checked | Who | Sheet |
|---|---|---|---|
| 1 Survey sign-off | The Built lines: openings, walls, floor and ceiling levels against the limits you assumed | Contractor and workshop; designer signs | Site survey |
| 2 Shop drawing approval | The Made and Between lines are on the drawing; critical dimensions are flagged | Designer | Shop drawing checklist |
| 3 Mock-up or first-off | Gap, flushness and match, judged as agreed | Designer, with the workshop | Prototype and mock-up |
| 4 Before dispatch | Critical dimensions, measured and recorded | Workshop | Inspection and test plan |
| 5 At fitting | Fit against the survey; notice if the building is outside the assumed limits | Installer | Site readiness |
| 6 Handover | Acceptance, in the viewing conditions agreed | Designer and client | Snagging criteria |
Say how it is viewed. One warranty manual judges skirting joints and painted surfaces from 2 m in daylight with no artificial light shone on them, and abrasions on factory-finished components from 0.5 m (LABC Warranty Technical Manual Version 11, 20.1.3, 20.1.6 and 20.1.7). Those figures are a warranty’s, not yours. The principle is the useful part: an appearance tolerance with no viewing condition cannot be settled.
When a tolerance is exceeded
- Built lines: the notification clause below. The contractor tells you before fabrication begins, and the parties agree a correction, a revised scribe margin or a variation. See joinery tolerances and scribing for who usually corrects what.
- Made lines: rework, replace, or accept by a written concession. The designer decides and the workshop records it.
- Between lines: usually a detail question. If the gap cannot absorb the variation, change the detail rather than the number.
- Cost and programme: who bears them for each line is a contract matter. Write it next to the line, not in a separate letter.
- Concessions are not precedents. Record each against the line and the item, so that it is not read as a change to the tolerance. See snagging acceptance criteria.
Specification wording
Paste into your schedule or specification and replace anything in [square brackets] with your own figures. Wording is a starting point: your specification governs.
A tolerance schedule, ref [ ], forms part of this specification. Each line gives a datum, a method of measurement, the conditions, the party who checks it and when, and the basis of the figure. Where figures differ the order is: (1) a tolerance on the approved shop drawing; (2) the tolerance schedule; (3) the class of [standard and edition] named on the drawing; (4) the workshop's declared tolerance for the process, ref [ ]. Each shop drawing dimension carries a tolerance or refers to the class in (3). 'Normal' tolerances are not accepted.
The joinery is designed on the assumption that walls, floors, ceilings and openings are within [3] mm of flat on a 2 m straightedge and [8] mm of plumb in [3] m (basis: [state the source and edition]). [The main contractor] confirms this by survey [ref] before shop drawings are fixed. Where the measured conditions exceed these limits, [the contractor] notifies [designer] in writing before fabrication begins, and the parties agree [correction by the contractor / a revised scribe allowance / a variation] before production.
Tolerances are measured by [party] with [instrument], at [ ] degrees C and [ ] % relative humidity where it matters, at the hold points in [inspection and test plan ref], and recorded on [form ref] with the date and name. Appearance (joints, gaps, finish, match) is judged [from [ ] m, in natural daylight / in the lighting of the finished space] against approved sample [ref] or mock-up [ref].
Where finished work is outside a tolerance, [the workshop / the installer] notifies [designer] in writing within [ ] working days, with the reading. [Designer] decides: rework, replace or accept. An acceptance is a written concession recorded against the schedule line and the item; it does not change the tolerance. Built conditions outside the assumed limits are corrected by [the main contractor].
Terms used on this page
- Tolerance
- The variation either side of a stated size that is agreed to be acceptable. Write it with a datum and a method of measuring.
- Scribe
- An oversized strip or edge cut on site to follow an uneven wall, floor or ceiling, so that no gap shows. Draw the margin.
- Critical dimension
- A dimension on which a fit, a limit or a joint depends. It carries its own tolerance on the drawing and is measured and recorded.
Standards and sources
- LABC Warranty Technical Manual Version 11, Section 20 Tolerances (pp. 448 to 456; December 2022): 20.1.3, 20.1.5 to 20.1.7 read 5 Nov 2026. Version 13 (quotes from 1 Jan 2026): change list read, Section 20 not.
- BS 5606:2022; BS 8000-0:2014+A1:2024; BS 8000-5:1990; BS 1186-2:1988: BSI listings: all Current (BS 1186-2 under review). Not read.
- BS EN ISO 13920:2023; BS EN 22768-1:1993: BSI listings: Current (22768-1 under review). General tolerance classes; scope text only.
Questions we are asked
What tolerances should I write into a bespoke joinery or furniture specification?
Not one number. Write a schedule with a line for each of three things: the piece as made (the workshop’s figure), the building it goes into (the limits you assume, then survey) and the gap between (a scribe or shadow gap detailed on the drawing). Give each a datum, a method of measuring, who checks it and when, and what happens outside it. No UK standard we could read supplies the figures, so ask the workshop what it holds and write that.
Is there a British Standard for joinery or furniture tolerances?
BSI lists several that bear on it: BS 5606:2022, a guide to accuracy and tolerance in design and construction (current); BS 8000-0:2014+A1:2024, workmanship on construction sites, which covers tolerance, accuracy and fit as general principles (current); BS 8000-5:1990 for site carpentry, joinery and general fixings (current on BSI’s listing); and BS 1186-2:1988 for workmanship in joinery (current, under review). We have not read them, so we quote no figure from them. Someone with access should confirm what each gives for joinery and furniture.
Can I use a warranty manual’s tolerances as my specification?
Only as a reference for the building. LABC Warranty’s manual says it measures only the tolerances it identifies and that a more stringent tolerance may be stated in a standard, and its figures are acceptance levels for new homes. The figures on this sheet are from Version 11 (2022). LABC Warranty now lists Version 13 for quotes from 1 January 2026, with changes in the tolerances section that we could not read, so check the current manual.
What does ‘general tolerances’ mean on a drawing?
A reference to a class in a standard, so that every dimension without its own tolerance still has one: BS EN ISO 13920 for welded work and BS EN 22768-1 for machined or sheet-formed parts. BSI’s scope text for the first says the tolerances stated on the drawing always apply and treats sizes with no tolerance and no adequate reference to the general tolerances as incomplete documentation. Name the class and the edition.
Who is responsible when the walls are out of true?
The contract decides. Write the limits you assume and a notification clause: the contractor tells you before fabrication begins if the survey shows more, and the parties agree a correction, a revised scribe or a variation. Our joinery tolerances and scribing sheet shows who usually corrects what.
Should I ask for the tightest tolerance available?
No. A tight tolerance needs more machining, checking and rework, and it can affect price and programme. Put tight figures where a fit or a limit depends on them, and ask the workshop what each one involves before you commit.
Download the factsheet
A two-page A4 PDF with the made, built and between table, the order of precedence, a compact tolerance schedule and four paste-in clauses, to keep with your project file.