Do I REALLY need a Class ‘A’ louvre?

Not always. Although Class ‘A’ louvres provide the highest level of rain defence under BS EN 13030, they are not required for every application. Whether you really need a Class A louvre depends on the criticality of the plant, the building’s exposure, and whether secondary weather protection is present.

You may genuinely need a Class A louvre if:

· The plant behind the façade is mission-critical, such as equipment in data centres, hospitals, laboratories, or control rooms.

· Sensitive electrical or mechanical systems could be damaged by even small amounts of water ingress.

· The opening is highly exposed to wind-driven rain (e.g., rooftop plant, coastal developments, or tall buildings).

· The louvre acts as the primary weather barrier with no secondary protection behind it.

· High airflow rates must be maintained while still ensuring robust moisture control.

However, in many situations a Class A louvre is not necessary, and a Class B, C, or D louvre may be entirely appropriate. For example:

· Where plant is non-critical and minor water ingress poses minimal risk.

· Locations with reduced exposure, thanks to overhangs, recesses, or neighbouring structures providing shelter.

· Plantrooms with secondary weather protection, such as internal sumps, drip trays, or secondary duct-mounted weather louvres.

· Unenclosed roof plant areas, where the louvre provides more of a visual screen than true weather protection.

· Architectural screening applications where airflow, cost, or aesthetics take precedence over rain defence.

· Situations prioritising higher free area or lower pressure drop over maximum weather protection.

Choosing a Class A louvre where it isn’t required can lead to unnecessary cost—due to increased material, deeper framing, or longer installation time—as well as higher pressure drops or a more complex system design than the project actually needs.

At Solinear, we help design teams determine whether a Class A louvre is genuinely required, or whether a lower class can deliver the right balance of airflow performance, weather protection, cost efficiency, and façade integration. Our Aquarius X-LINE range includes Class A, B, C, and D options to ensure the louvre selected is fit for purpose, not over-specified.

For a practical breakdown of which weather louvre class suits different applications, see “What real-world applications are Class A, B, C and D louvres suitable for?”