Construction products in the UK and EU are governed by the Assessment and Verification of Constancy of Performance (AVCP) system. This framework determines how manufacturers test, document and declare the performance of their products—and crucially, who is responsible at each step. Unlike most CE or UKCA conformity marking, which relies on a pass-or-fail Declaration of Conformity, construction products require a Declaration of Performance (DoP). The DoP states measured values or performance classes for essential characteristics, not blanket compliance with a fixed threshold. The AVCP level assigned to your product dictates whether you can conduct testing in-house or must involve an independent notified body.

According to the UK government Construction Products Reform White Paper published in February 2026, AVCP is "a harmonised system defining how to assess products and control the constancy of the assessment results." The European Commission adds that the system "safeguards the reliability and accuracy of the Declaration of Performance" and prescribes five different levels "ranging from large-scale third party involvement to self-declaration and monitoring by the manufacturer." Your product's harmonised standard or European Assessment Document specifies which AVCP level applies—and sometimes different levels for different characteristics such as reaction to fire.

What are the five AVCP systems?

AVCP levels increase in manufacturer autonomy as the number rises. The system assigns responsibility for initial type testing (ITT), factory production control (FPC) audits and continuous surveillance:

  • System 1+: A notified certification body conducts initial type testing with sampling at the factory, performs an initial factory audit, sets up continuous surveillance and assessment of the FPC, and completes audit testing of samples before the product is placed on market. The body then issues a Certificate of Constancy of Performance (CCP). The manufacturer draws up an FPC and agrees a continuous testing plan. System 1+ does not currently feature in any standards for insulation products.
  • System 1: Similar to 1+, but without pre-market audit testing of samples. The notified body carries out ITT with factory sampling, conducts an initial factory audit, and provides continuous surveillance and assessment of the FPC, then issues a CCP.
  • System 2+: The manufacturer performs the ITT, draws up the FPC and agrees a continuous testing plan. A notified certification body conducts an initial factory audit, sets up continuous surveillance and assessment of the FPC, and issues a certificate of conformity of the FPC (not a full CCP). Manufacturers under AVCP 2+ or 3 may voluntarily choose to declare critical performance characteristics to a higher AVCP level to demonstrate commitment to a high standard of performance.
  • System 3: The manufacturer undertakes the FPC while a notified laboratory carries out the ITT based on samples provided by the manufacturer. No continuous surveillance is required.
  • System 4: The manufacturer draws up an FPC and conducts the ITT to enable preparation of the DoP. No notified body involvement is required—self-declaration only.

Why does reaction to fire often require System 1?

Harmonised product standards frequently assign AVCP System 1 for reaction-to-fire characteristics, even when other essential characteristics of the same product fall under System 3 or 4. This reflects the safety-critical nature of fire performance. For example, thermal insulation products manufactured to EN 13166:2012 are assessed against AVCP System 1 for reaction to fire, requiring continuous monthly testing of product samples. While manufacturers can perform this testing in-house, independent notified body oversight remains mandatory for the issuance of the Certificate of Constancy of Performance.

When is a notified body required?

Any product subject to AVCP System 1+, 1 or 2+ must involve a notified certification body. These bodies—accredited testing and inspection organisations—issue either a Certificate of Constancy of Performance (Systems 1+ and 1) or a certificate of conformity of the FPC (System 2+). Under System 3, a notified laboratory conducts only the initial type testing; no certificate of FPC or continuous surveillance is required. System 4 products require no notified body involvement at all. The specific AVCP level for your product is defined in the harmonised standard's Annex ZA or in the European Assessment Document.

How does AVCP interact with national building regulations?

A common misconception is that AVCP compliance guarantees a product meets local building codes. It does not. Construction works are regulated at national, regional or even local level, so acceptable fire classes, thermal values or load capacities vary. The DoP declares measured performance—for instance, a thermal conductivity of 0.035 W/mK or a fire classification of Euroclass B-s1,d0—but the specifier, contractor or national authority must then check whether that declared performance satisfies the project's requirements. AVCP ensures the declared values are tested and documented using a harmonised method, not that they meet a universal threshold.

Building a compliant documentation trail

Manufacturers should maintain a clear audit trail linking the AVCP system to every DoP. This includes test reports from notified bodies (Systems 1+, 1, 2+ and 3), factory production control procedures (all systems), continuous surveillance records (Systems 1+ and 1) and ITT certificates. When national market surveillance authorities inspect product documentation, they will expect to see the correct AVCP level applied, the corresponding notified body number (if applicable) on the DoP, and evidence that the declared performance matches the test results. Misclassification—applying System 4 self-declaration to a product that requires System 1—can result in product withdrawal, fines and reputational damage.

For detailed guidance on how AVCP integrates with UK Construction Product Regulations and UKCA marking, consult the Office for Product Safety and Standards or your notified body. If your product standard is unclear, the technical specification's Annex ZA—or equivalent section in an EAD—is the definitive reference for which AVCP level applies.