Louvres & Grilles

Frequently asked questions

What's the difference between a weather louvre and a grille?

A weather louvre mounts on an external wall or duct opening; its angled blades keep rain and debris out while letting air pass, so it is used wherever a duct meets the outside. A grille is an internal terminal that distributes or returns air within a room, on a wall, ceiling or door. Many installs use both: a weather louvre outside and a deflection or egg-crate grille inside.

What is free area, and why does it matter?

Free area is the actual open area left for air to pass through once blades and frame are deducted, always less than the overall size. Fan performance depends on it: too little free area adds resistance and cuts airflow. Size the louvre or grille so its free area suits the fan's duty; we can advise the right size for your airflow.

Which grille for supply and which for extract?

Double-deflection grilles let you aim the air stream horizontally and vertically, so they're used on supply where throw and direction matter. Single-deflection and egg-crate grilles suit extract and return air. Non-vision grilles block line-of-sight through door and wall transfer openings while still passing air.

Do you supply custom sizes?

Yes. Pressed-steel grilles are stocked from 150mm to 600mm square, and the egg-crate grille is available made-to-size. For bespoke louvre sizes, colours or free-area requirements, see our made to order louvres and grilles, or send us the opening dimensions and target airflow and we'll quote.