Value Engineering Roof Coating Specifications
| Bitesize CPD
When a cheaper alternative is not equivalent
Value engineering should improve the relationship between cost, performance and project requirements.
It should not simply replace a specified roof coating system with a cheaper product.
A proposed alternative may appear similar because it is described as a roof coating, offers a comparable warranty period or can be applied in a single coat.
That does not establish technical equivalence.
The original specification may include independent certification, defined preparation standards, primers, corrosion treatments, detailing products, minimum film thicknesses and application limitations.
If some of these elements disappear during substitution, the price may reduce because the scope and evidence have also been reduced.
That is not necessarily value engineering.
It may be specification dilution.
How substitutions arise
Roof coating substitutions are frequently suggested during tendering rather than during the original specification process.
A main contractor may ask a roofing subcontractor to identify savings. The subcontractor may then consult the operative or spray team that will carry out the work.
The recommendation can therefore originate with the person applying the coating rather than the person responsible for assessing the roof, designing the remedial work or evaluating the technical evidence.
Experienced applicators can provide valuable practical information.
However, familiarity with spraying a product does not demonstrate that the proposed system is equivalent to the one specified.
Installer preference is not technical justification
An installer may recommend a particular product because:
- it is familiar;
- it sprays easily;
- it is readily available;
- the installer already holds stock;
- the manufacturer offers favourable commercial terms;
- fewer preparation or detailing stages are required;
- it allows the work to be completed more quickly.
The recommendation may be entirely genuine. It may also be influenced by supply arrangements, rebates, commissions or other commercial incentives.
Any relevant commercial interest should be transparent.
More importantly, none of these factors establishes that the alternative provides the same technical performance, certification or system build-up as the specified system.
The question is not whether the contractor likes using the product.
The question is whether it is suitable for the roof and genuinely equivalent to what it is replacing.
Compare the complete systems
Roof coating comparisons are often reduced to the top coat.
This can produce a misleading like-for-like comparison.
A complete roof refurbishment system may include:
- substrate-specific primers;
- treatment of exposed corrosion;
- separate cut-edge corrosion materials;
- fixing repairs or replacement;
- sealants and reinforcement products;
- rooflight interfaces and penetration details;
- defined surface preparation;
- minimum application thicknesses;
- inspection and quality-control requirements.
Two top coats may have similar descriptions while the complete systems differ considerably.
A valid comparison should examine every component, operation and limitation—not simply the price per litre or stated coverage rate.
What may be removed during “value engineering”?
Independent certification
The specified system may have been independently assessed for a defined substrate, preparation method, system build-up and intended use.
A cheaper alternative may have no equivalent certification or may rely only on manufacturer-generated information.
The absence of certification does not automatically make a product unsuitable.
It does mean that a source of independent evidence has been removed and that the decision should be made knowingly.
Preparation requirements
Surface preparation is one of the largest cost elements in many roof coating projects.
A lower quotation may result from reduced cleaning, corrosion removal or treatment of deteriorated factory finishes.
The coating may not be the principal saving.
The saving may come from doing less work before it is applied.
Primers and ancillary products
A proposed substitute may omit primers, corrosion treatments or separate detailing materials included within the original specification.
This changes the complete system, even where the top coat appears broadly comparable.
Applied film thickness
Coverage rates should be examined carefully.
A lower-cost system may be applied at a reduced wet or dry film thickness. Alternatively, stated theoretical coverage may not allow adequately for the profile, surface condition, application losses or additional material required at vulnerable details.
Application limitations
Statements such as “single coat”, “damp tolerant” or “all-weather application” require proper examination.
The application conditions, substrate moisture limitations, curing requirements and preparation standards should be established from technical evidence rather than headline marketing claims.
Warranty scope
Warranty periods alone do not provide a like-for-like comparison.
The reviewer should establish:
- who issues the warranty;
- whether it covers materials, workmanship or both;
- what conditions must be satisfied;
- what exclusions apply;
- whether inspection or maintenance is required;
- what remedy is actually provided if the system fails.
A longer stated period does not necessarily provide broader protection.
BBA-approved and non-BBA systems
A BBA-approved system is not automatically required for every roof coating project.
Non-BBA systems may be entirely appropriate where certification is not required and the client has made an informed decision based on the project circumstances.
However, a non-BBA system should not be presented as directly equivalent to a BBA-approved system without explaining the difference.
Where certification formed part of the original specification, its removal should be:
deliberate, transparent and technically justified.
The cost saving should then be considered alongside the evidence and assurance that have been removed.
Who carries the risk?
The person suggesting the substitution does not necessarily retain the long-term consequences of that decision.
The main contractor may face call-backs, delays and contractual disputes.
The roofing contractor may face premature failures or warranty claims.
The surveyor or specifier may be asked why the original specification was changed.
The facilities manager may inherit repeat maintenance and disruption.
The asset owner ultimately carries the effect on service life and lifecycle cost.
A short-term material saving can therefore transfer a disproportionate amount of risk to the wider project team.
Value engineering requires evidence
A lower price is not automatically better value.
A proposed alternative may be appropriate. It may even offer a genuine project benefit.
But the case for changing the specification should be based on evidence, suitability and a complete system comparison.
It should not be based solely on what an installer prefers to spray.
When certification, preparation and technical due diligence are quietly removed, the saving may come from transferring risk—not creating value.
Reflective questions
When reviewing a proposed substitution, consider:
- What has changed apart from the manufacturer’s name?
- Which parts of the original specification have been omitted?
- Has technical equivalence been demonstrated or merely asserted?
- Who recommended the change, and on what evidence?
- Are any commercial interests relevant to the recommendation?
- Could the decision be justified clearly if the system were challenged following a later failure?
Conclusion
Value engineering can be constructive when it produces a more efficient solution without compromising the required outcome.
It becomes problematic when dissimilar systems are compared superficially and important differences are hidden within a reduced price.
Roof coating systems should be compared in full.
Certification, preparation, detailing, application requirements and warranty scope all form part of that comparison.