Seating sit-test and comfort sign-off

At a glance

Numbers in [square brackets] are starting values to agree, not figures from a standard. The partner workshop confirms which stages are practical and what can change after each.

What a sit test is for, and what it is not

Dimensions on a drawing do not tell you how a seat feels after twenty minutes. Foam compresses, a cover stretches, a front edge that looked right presses behind the knee, and a back that supports one person misses another. A sit test finds that out on a full-size piece while a change is still cheap, and leaves a record that the designer and client agreed the result.

• It is a comfort and fit approval. A small panel sits, the same points are measured and scored every time, and the designer signs.
• It is not a strength or durability test. For seating used outside the home that is BS EN 16139, whose title and scope are safety, strength and durability. BS EN 1728, the test-method standard it builds on, is listed by BSI as test methods only: it “does not include any requirements”.
• It is not an ergonomic assessment or a certificate. No standard we have read gives a pass mark for comfort. A sit test records what one group of people thought of one prototype.
• It is not a fire test. Fire evidence is a separate file: see BS 7176 hazard categories.

Laboratories can compare seats more objectively with interface pressure mapping, a sensor mat that shows where the body presses. FIRA publishes a guide to using it to judge comfort (14 July 2020). It was written for mattresses and says its findings may apply to other products such as seating, but the full text is restricted to members and has not been read for this sheet. The protocol below needs no equipment.

Four stages, and what each one settles

Which stages are built, how long they take and what can still change after approval is agreed per project with the partner workshop. Our design development page says mock-ups and prototypes are available for complex or high-value commissions, so ask early. The stages run from cheapest to change to hardest.

1. Dimension mock-up. A full-size shape in foam blocks or timber with no final cover. It settles seat height, depth, back and arm height and how the seat meets the table. A banquette is best tested in place against the real table height.
2. Full-spec prototype. The production frame, filling and suspension with a plain or the final cover. It settles feel over time, back support and how the seat recovers after someone stands. The main sit test happens here.
3. Pre-production approval. The first item with the real cover, trim and finish. It settles cover fit, seams and piping, finish and any change made since stage 2. Shorten the sit if the shape has not changed.
4. Post-delivery check. The delivered item in its room, beside the retained benchmark. It settles fit with the real floor, table and light, and whether the delivered item matches what was approved.

Who sits, for how long, and how

The panel. Use at least [four] people, including one small and one large adult at the two ends of the range the seat is meant for (designers sometimes call these the 5th and 95th percentile), and the rest in between. If the venue has staff who will use the seat daily, include one. If the public will use it, include a tester who pushes up with the arms to stand. Record a height band for each tester, not a weight, and no names unless people are happy to be named. A panel this size is a fitting session, not a statistical test, so do not report percentages.

Time. A seat can feel fine for the first minute and fail by the tenth. Sit for as long as people will really stay. Starting values, to agree with the workshop:

Conditions. Test at the real table, or a table of the same finished height, on a floor at finished floor level, in the shoes and clothes people will wear, in similar light. If you are comparing two prototypes, do not tell testers which one you prefer.

The sit, step by step.

1. Measure the seat empty before anyone sits.
2. First sit, about a minute. Take the first impression before anything is scored.
3. Measure the seat height again, as sat on, with the tester in the seat.
4. Timed sit with a real task: eating, writing, talking, reading.
5. Rise and sit three times.
6. Lean back and forward, shift sideways, push on an arm.
7. Score at once, before talking to the other testers.
8. Then discuss, and write the decision and any change on the sheet.

The scoring sheet

One A4 page per tester, drawn below. Section A is measured with a tape and level and checked against the drawing; section B is scored 1 (poor) to 5 (good) straight after the sit; section C is the designer's decision. The factsheet carries a printable copy. The datums for the measured lines are on the seat height, depth and width and seat rake and slope sheets. This table says what each line is looking for.

A pass rule to start from. No line scored 1 by any tester. No line averaging below [3.5]. Any line scored 2 or lower by [two] or more testers is discussed, and either a change is written down or the reason for leaving it is recorded. Do not average away a problem for the small or the large tester: if one of them cannot sit comfortably and they are inside the intended range, that is a finding.

Alongside the sheet, look at edges, corners and any gap where fingers could be caught. That is a quick visual check by the designer, not a substitute for the tests in the standard.

Sign-off, the benchmark and changes after approval

Three outcomes: Approved, Approved with changes (each change written on the sheet and agreed before production) or Not approved (a revised prototype is tested again). Take photographs of the prototype in use, of the tape measurements and of the completed sheets, and file them with the drawing.

• Keep the approved prototype as the benchmark. Tag it, photograph it and keep it until practical completion. Our sampling page describes the same idea for finishes: approved samples are retained as the benchmark through production.
• Changes after sign-off are variations. Geometry, filling, suspension, cover and finish are changed only in writing, and the benchmark is updated to match.
• Check the first production item against the benchmark before the rest are made, and again on delivery. How far a delivered piece may differ is the subject of the furniture dimensional tolerances and snagging acceptance criteria sheets.
• Sign-off is a record of agreement, not a guarantee of comfort for everyone. Have the client's contract adviser check the wording before it goes into a contract.

Contractor to provide one full-size prototype of [item ref] for sign-off before production, built to the approved drawing [ref, revision] with the production frame, filling and suspension and [a plain / the final] cover. The approved prototype, tagged and photographed, is retained as the benchmark until practical completion. Production is not to start until the designer has signed the prototype 'Approved' or 'Approved with changes'.

The prototype is to be sit-tested by a panel of at least [4] people, including at least one small and one large adult within the intended users, each sitting for not less than [20] minutes at a table of finished height [ ] mm, and recorded on the sit-test record sheet [ref]. The designer records the results. No line is to be scored 1 by any tester. Any line scored [2] or lower by [two] or more testers is to be resolved in writing before approval.

Changes to the approved prototype's geometry, filling, suspension, cover or finish after sign-off are to be made only by written variation approved by the designer, and the benchmark is updated to match and retained for inspection until practical completion. The first production item is to be checked by the designer against the benchmark before the remainder is made [and again on delivery]; differences beyond [the agreed tolerance] are recorded on the snagging list.

Standards and sources

• BS EN 16139:2025: Furniture. Safety, strength and durability. Requirements and test methods for non-domestic seating. BSI listing: published 31 August 2025, current; adults up to 110 kg. A safety, strength and durability standard: it does not assess comfort.
• BS EN 1728:2012: Furniture. Seating. Test methods for the determination of strength and durability. BSI listing: current; test methods only, no requirements.
• FIRA: Pressure Mapping, Review of Validity to Assess Comfort of Mattresses, Guidelines for Best Practice: information page of 14 July 2020; the guidance PDF is restricted and was not read.
• Make Bespoke Studio: Sampling: approved samples retained as the benchmark.

Questions we are asked

How long should a sit test last?

As long as people will really sit. This sheet starts at [10] minutes for a dining or meeting chair, [20] for a banquette or bar stool and [30] for a lounge seat, because a seat that feels fine in the first minute can fail later. These are starting values to agree with the workshop, not figures from a standard.

Who should sit in the panel?

At least [four] people, including one small and one large adult at the ends of the range the seat is meant for, a daily user if there is one, and for a public venue someone who pushes up with their arms to stand. Record a height band, not a weight or a name. A panel this size is a fitting session, not a statistical test.

Does a sit test replace testing to BS EN 16139?

No. BS EN 16139 is a safety, strength and durability standard for non-domestic seating and does not assess comfort. A sit test does not test strength. Ask for both: the standard's test report for the model, and a sit test on the prototype for fit and feel.

Can you sit-test a banquette before it is built?

Yes, with a full-size mock-up in foam and timber, built to the drawing's depth, back angle and seat height and placed against the real table height. Test it again as a full-spec prototype with the production foam, because the cover and filling change how it feels.

What if the testers disagree?

Record every score and decide against the people the seat is for. Do not average away a problem for the smallest or largest tester inside the intended range. Where scores split, change one thing at a time and test again.

Is pressure mapping needed to sign off comfort?

No. It is a laboratory method. FIRA has published best-practice guidance on it, written for mattresses, but the text is restricted and has not been read for this sheet. A recorded sit by a small panel needs only a tape and a level.