The substitution and value-engineering register

At a glance

Re-sign: a new sample or signature. New test: the evidence is void until a new report is issued. Re-check: ask for the new certificate, claim or declaration. Check: confirm in writing. Practice guidance, not a standard: see Sources and caveats.

The test is the evidence, not the look

“Or equivalent” is a judgement about appearance and price. The question that decides what must be redone is a different one: what evidence points at the item? A fire test report names a cover, an interliner and a filling. A chain-of-custody claim belongs to a supplier. An EPD names a product. A sample signature names a batch, a finish and a process. Change the item and each of those stops describing what you receive, however alike the new one looks.

Our own process works the way a register wants it to. In our how we work and pricing pages, a package that comes back over budget is shown with the as-drawn price beside the alternatives, so the design team decides what changes, not the maker, and we agree every change before anything is cut. A change after approval is costed and approved in writing before work changes. The register is the record of that.

What can change without re-approval? Very little. Only tier A in the table below, and only where the specification lists the item as the maker’s choice, so that the list is agreed rather than assumed. Everything else needs the designer’s written approval, and anything that carries evidence needs that evidence re-checked first.

What each kind of change puts back in question

The table at the top is the summary. Four of its lines rest on documents we read.

Upholstery fire tests. The FIRA and British Furniture Confederation guide says test data applies to the item evaluated, not to the item later supplied. It says a basic alteration to a specification makes a new model that must be re-tested: a change of cover other than a simple colour change, of pattern or construction other than minor changes, of filling, or of component supplier. It adds that enforcement authorities normally expect a UKAS-accredited test certificate no more than a year old, and less for larger runs. That is what it says they expect, not a legal limit. See BS 7176 hazard categories and the fire documentation matrix.

Wall linings and panelling. Approved Document B volume 2 (England, buildings other than dwellings) says test evidence for a fire classification should be checked to see that it applies to the intended use, and that small differences in detail, such as fixing method, joints, dimensions and air gaps, might significantly affect performance and should be tested or assessed. It also says a reaction-to-fire classification is valid only when the product is fixed to a substrate of the kind it was tested on. So a change of board behind a veneer, of adhesive or of fixing is a change to the evidence. It is guidance to the Building Regulations: the fire consultant and building control decide what applies.

Timber claims. FSC UK’s buyer checklist looks for six things on delivery documents: the date, supplier and customer details, a product description, the quantity, the supplier’s certificate code and the FSC claim. A new supplier has a new code, and a move from FSC 100% to FSC Mix is a different claim. See specifying FSC and PEFC.

EPDs. An EPD covers the products it names. In the International EPD System an updated EPD is re-verified, and a substantial change to a product, meaning a different function or different major manufacturing steps, leads to the old EPD being withdrawn and possibly to a new one. So the EPD of the original does not carry over to a substitute: see how to read an EPD.

Samples. A change of material batch, supplier, process or finish after approval is a new sample and a new signature: see the sample hierarchy sheet. For a visible change to a room or a repeated item, a mock-up may need to be shown again.

The register: one line per proposed change

Keep one register for the project, beside the drawing register, and give each line a reference that is never reused. Anyone may raise a line. The designer decides. The columns below are a starting point, filled in here with two invented examples.

• Raise it before ordering. The line is approved, approved with conditions, refused or withdrawn before the item is ordered, not after it arrives.
• State the effect on time and cost as the maker’s own figure, in a revised quotation line, never in the register by assumption. This sheet gives no prices.
• Update the paperwork. A change that is approved goes onto a new drawing revision, the FF&E schedule and the sample register. The superseded sample is marked so.
• A change that moves the price or the programme is also a variation, and follows the written variation route in your contract.
• File the new evidence with the line, so that the project file shows what was checked, by whom and when.

Value engineering, without erosion

Our value engineering article sets the order: state the design intent first and agree what must not change, then look for the smarter route. The register fits that order. Put the things that must not change at the top of the specification, price the as-drawn version and the alternatives as separate options, as the quote comparison sheet advises, let the designer choose, and then log each chosen change.

Count the whole saving. A swap that needs a new composite test, a new sample or a new certificate has time and cost of its own. Ask the maker to state them in the revised quotation, so the design team sees the net effect, not just the headline.

Define “or equivalent” or do not use it. If the specification allows equivalents, say what the term means: the same appearance as signed sample [S-nn], the same sizes within the stated tolerance, the same published performance data, the same kind and standard of evidence, and a named supplier. An item that meets those points still goes through the register, as an alternative offered separately with its data sheet. This is the gate the joinery specification sheet describes.

No substitution, alternative or 'equivalent' for any item, material, finish, component or supplier named in the drawings, specification, FF&E schedule or approved samples is to be made without the written approval of [designer], given on substitution register [ref] before the item is ordered. The proposer states the reason, the effect on appearance and function, the evidence that names the original (test reports, certificates, claims, declarations, warranty), what will replace it, and the effect on programme and contract sum as stated in the maker's revised quotation. 'Equivalent' means an item approved under this clause, not an item the supplier judges equivalent.

A substituted item is not approved until the supplier provides evidence of the same kind and standard as for the item it replaces: [a test report for the new upholstery composite, from a UKAS-accredited laboratory, dated within [12] months] [the supplier's certificate code and claim on the delivery document] [a declaration of performance and emissions class] [an EPD to the same PCR, in date] [warranty terms]. Where that evidence cannot be supplied, the substitution is refused.

[Maker] may change the following without prior approval, if the register is updated and the item is named in no approved sample, report, certificate, claim or declaration: [concealed fixings of the same type and rating]; [assembly sequence and jigs]; [ ]. Everything not listed needs approval.

Work that departs from an approved item without written approval on the register may be rejected. [Remedy, and who bears the cost of removal, replacement and re-testing, to be agreed with the project's contract adviser.] Approved changes are made by new drawing revision and, where they move the price or programme, by written variation.

Standards and sources

• FIRA and BFC: Fire safety of furniture in the contract and non-domestic sectors (2010, updated 2011): A1.1 and A1.3 read. BS 7176 itself not read.
• Approved Document B volume 2, Appendix B, B2 and B8 (2019 edition, amendments to 2026): England, buildings other than dwellings. Read.
• FSC UK: new buyer guides (7 Jul 2026): delivery checks and claim types.
• International EPD System: General Programme Instructions 5.0.0, section 6.8: hosted copy read; 5.0.1 not read.
• Make Bespoke Studio: Pricing; How we work: alternatives beside the as-drawn price.

Questions we are asked

Can the maker swap a board for an equivalent one?

Not without the designer’s written approval, and not before the evidence has been re-checked. A board can carry a declaration of performance, an emissions class, a timber claim and a fire class that applies to the finished build-up. A look-alike board has none of them until the supplier shows it does.

Does changing the fabric colour need a new fire test?

The FIRA and BFC guide says a change of cover other than a simple change of colour makes a new model that must be re-tested, so a plain colour change is the exception. Confirm with the test house that a dye change does not alter the back-coating or any treatment, and ask for it in writing.

Does a cheaper timber or veneer need re-approval?

Yes. A different species, cut, flitch or supplier needs a new sample, which for natural materials should show a range, and a new certificate code and claim from the supplier if timber claims are specified.

Who pays for re-testing or a new sample?

The contract decides, and this sheet gives no prices. Ask the maker to state the cost and the time of any re-test, new sample or new certificate as a line in the revised quotation before the change is approved, so the net saving is visible.

Does value engineering mean cheaper?

Not necessarily. Our article describes it as protecting the design intent and finding a smarter route to the rest, and notes that durability is value. Some changes cost the same and last longer. The register records them all the same way.

How do I avoid “or equivalent” taking over?

Say what it means in the specification, require the alternative to be offered separately with its data sheet and a sample, and approve it on the register before the order is placed. Without that, the supplier decides what counts as equivalent.

Is a substitution the same as a variation?

Not quite. A substitution is a change to what is specified, and the register records it. A variation is the contractual instruction that changes price or programme. A substitution that moves either is also a variation.