How to read a declaration of performance

Why “there is a declaration” is not enough

The existence of a declaration verifies nothing on its own. Verification works when the declaration is for that product, for that purpose and for that performance which the design requires.

That takes four comparisons.

1. The product type identifier

The unique identification code at the top of the declaration has to be compared with the product actually installed — with the name on the packaging and the delivery note.

This is where the most common fault arises: the manufacturer hands over the declaration for a similar but different type, because that is the one to hand.

2. The intended use

The declaration states what the product was intended for. If a board was declared for internal wall lining, it cannot be relied on in an external, weather-exposed position — even if it can physically be fixed there.

3. The declared values

Characteristic by characteristic, compare against the design requirement: fire class, thermal conductivity, strength, vapour permeability, water absorption — depending on its role.

This is where it emerges whether the “same thing, only cheaper” substitution really is the same.

4. The NPDs

NPD (No Performance Determined) means the manufacturer declared no performance for that characteristic. That is not a fault or a deception — it simply means that property cannot be relied on.

If the design expects a fire class from a material and the declaration says NPD there, the product is not suitable for that purpose, however good it otherwise is.

What else to look at

• Date of issue and version number — manufacturers update them from time to time.
• The technical specification referred to: the number of the harmonised standard, ETA or NMÉ.
• The number of the system of assessment and verification: the stricter it is, the greater the role of external checking.
• The signature: whether anyone actually issued it.

Where to store it

Tied to the place of installation. A folder of PDFs with no way of telling which product is in which wall is worth almost nothing at handover. Fire documentation.

The point

Reading a declaration is not administration but a professional check. Five minutes tells you whether what is specified and what is installed are the same thing.