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"There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey."

John Ruskin (1819-1900)

With the growth in Design and Build, Construction Management, Management Contracting and their many hybrids, I have seen changes in specification practice, which are eroding the position of the designer and the quality of the end building. Increasingly the requirements and methods of these procurement methods have filtered their way back to General Contracting and it has become more commonplace for Contractors to offer alternative products to those specified, usually offering potential savings.

If there is a project budget or cost plan for the building and tenders are within these figures then there should be no need to consider alternatives. Potential savings may be offered but it will be up to the QS, if there is one, to ensure the savings find their way to the final sum not just the contractor's profit margin.

Coping with 'Substitution'

Product Quality and Design Life

It needs to be understood that potential savings usually mean diminished quality and life expectancy. Often cheaper initial costs means more expensive in-use costs: running, maintenance and replacement costs and increases in maintenance and replacement frequency.

There is a need to balance initial and in-use costs and for informed decisions to be made. Life Cycle Analysis (LCA) and Component Life (CL) comparisons offer this opportunity.

Davis Langdon Everest Consultancy (DLEC) carried out research and published some information on LCA via 'Building' magazine articles, but comprehensive published information is not yet available from DLEC.
Building Performance Group (BPG) developed and with SPON, published Component Life Manuals (CLM) for Housing Association Property Mutual (HAPM), non-housing elements in Building Fabric Component Life Manual (BFCLM) and services components in the BLP CLM. These give guidance on the expected life (insurable life), modes of failure and maintenance requirements of many if not all components used in buildings. Their use at the design stage can help the designer to select all components to match a predetermined design life and achieve some consistency across the range of components. With this information the designer, client and Quantity Surveyor (QS) can also review potential savings, carrying out a series of balancing acts comparing a potential saving in costs with a consequent reduction in component life.

On studying the content of these CLMs it becomes clear that product quality is the key to life expectancy. Usually in the form of BSI Kitemark and BBA certificates, but also other schemes like BRE Certification Technical Approvals (formerly WIMLAS), SGS Yarsley Testguard, CARES, BWF Certifire, and European schemes including European National Agrément Schemes, European Technical Approvals (ETA) and Euro-Agrément.

These schemes have a number of things in common, the products is usually made to a published regulation, code of practice or standard; tested or monitored to ensure they comply (Product Quality) and management procedures are checked to ensure consistency can be achieved in production (Quality Assurance). Alternatively, they depart form those regulations, standards or codes in tried, tested, defined and controlled ways and have been independently assessed on those departures.

'Or Equivalent Approved'

Since 1956 LEEDSFORD V CITY OF BRADFORD Case law the use of the term ‘or otherwise approved’ in a specification does not mean the designer must consider alternatives offered by the contractor, nor that the designer must give a reason for not considering alternatives offered.

Many European Directives and their implementing national legislation, in particular the Construction Products Directive (CPD) and the Building Regulations (Regulation 7) were published or updated in the years leading up to or following 1992 when the United Kingdom formally joined the European Market.

Whilst the terms 'or similar' & 'or equal' were in common use for decades leading up to 1992, the term 'or equivalent' began to have greater significance in European Law and in particular related to government financed 'Public Works' projects.


The term 'or equivalent' was in use in standard specifications in particular in PSA General Specification and NBS National Building Specification Preliminaries.
OR OTHERWISE APPROVED did not suggest equivalency,
OR SIMILAR is a weak term by comparison with 'or equal' and should be avoided,
OR EQUAL sounds okay and is okay in UK on non-government projects,
OR EQUIVALENT has greater meaning in EU legal definitions, in EU directives and the UK national legislation implementing them. It is required on all Government financed 'Public Works'.
But OR EQUIVALENT can mean same performance but a different way to achieve that performance,
e.g. roof slate v clay tile, so its also important to control appearance and profiles too.
OR EQUIVALENT AND APPROVED is not strictly necessary but a useful reminder and APPROVED needs also to be defined, it is in NBS preliminaries.

here be dragons

However OR EQUIVALENT AND APPROVED can be problematic when a contractor substitutes without the CA's knowledge and the CA signs-off stage payments for work containing substituted and potentially inadequate materials, is effectively approving the inadequate materials without knowing it.
So its back to OR EQUIVALENT and no more.

The term 'or equivalent' needs definition and ground rules and NBS Clause A31/200 does just that. It requires any proposed substitutions to be notified to the Contract Administrator (often but not always the Architect) submitting evidence in the form of English language test results, certificates, specifications, details, guarantees, etc. These must show equivalency of materials, safety, reliability, appearance, durability, function, of products and all accessories, etc.

NGS GREEN BUILDING SECIFICATION work sections, clauses and appendix

GBS clauses address specification substitution. One of the issues that they address is the time involved in checking contractors proposed alternatives. The designer will have gone to the effort to select materials, understand their requirements, design with them and specify them. The last thing the designer wants is to have to go through the whole process again for an alternative material offered by the contractor. The important issue is to make the contractor fully responsible for the whole process of proving the equivalency and suitability of their proposed departure from the designer's proposal. In this context, the more detailed the clause the less likely an alternative material will be found to match all characteristics and a clause describing a product where alternatives will be considered need not be in so much detail.

It is important that a clause requires the tender to be strictly in accordance with the Contract Specification, Drawings and Bill of Quantities to allow comparison of tenders on apples for apples basis. Alternatives and options need to be offered as a separate submission along with the compliant tender, to allow comparison of apples with pears and/or pears with oranges from different tender's.

It can be useful to require a reason for the substitution, as well as asking for all evidence of equivalency in respect of all items of a descriptive clause, comparison and highlighting of the relevant information. Where a substitution for a specified material, component or system is proposed as part of any alternative tender and depending upon the designers initial research, any of all of the following can be asked for in the Specification:
Manufacturer's illustrative and technical literature, Performance characteristics, Test results and/or assessments, Third party independent accreditation; Specification, Drawings, Method statements; CDM Risk assessment, COSHH data sheet review; Environmental assessment of manufacturer, materials, country of origin, transport methods and embodied energy, Life Cycle Costing, Component Life Assessment. (based on HAPM/BPG/BPL CLM), Information of availability of spares and maintenance materials in the UK.

Where insufficient or no evidence is provided, substitution should not be considered.

Subsequent Substitutions

If further specification substitutions are proposed during the construction, the Contractor should be required to provide all such information with at least one months notice of date of ordering materials. This will allow thorough evaluation by the design team, in time to meet the Programme. Late submissions should be discouraged and ideally not be considered. Any substitutions carried out without such submission and subsequently detected, should be subject to thorough comparison and submissions and if found wanting, required to be replaced with the specified or compliant materials.

WREN PII Insurance

NGS hear through providing NGS CPD IN-HOUSE that Specifiers are required to state 'Or equivalent' in every product clause in government work. This encourages substitution and is read by contractors as permission to substitute and substitute surruptitiously.  We think this is a dangerous precedent that will undermine the specification and potentially reduce the quality of the building, but comply with EU rules as interpreted by insurers interpreting case law.

© ASWS, NGS, BrianSpecMan aka Brian Murphy
2003, updated 2004,
10th February 2013 - 3rd August 2013


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© NGS BrianSpecMan aka Brian Murphy
3rd March 2013 - 4th May 2014

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© NGS BrianSpecMan aka Brian Murphy
10th February 2013 - 4th May 2014