Pressed Steel Grilles

Pressed steel grilles are heavy-duty fixed-blade ventilation grilles built from mild steel with a robust pressed construction. We stock them in 9 square sizes from 150×150mm to 600×600mm, each with 67% free area and a choice of white or silver powder-coated finish. Designed for wall or door mounting in both internal and external applications, they're a practical choice for plant rooms, risers, door transfer ventilation, car parks and anywhere that needs a tough, tamper-resistant grille. All sizes in stock with next-day delivery available.

Egg Crate Grilles / Double Deflection Grilles / Single Deflection Grilles / All Grilles & Louvres / Fire Dampers

What is a pressed steel grille used for?

A pressed steel grille covers a ventilation opening in a wall, door or bulkhead, allowing air to pass through while providing a clean, durable finish. The fixed angled blades direct airflow downward at a set angle and prevent direct line-of-sight through the grille. Common applications include door transfer grilles (allowing air to move between rooms without leaving the door open), plant room ventilation, riser cupboard vents, commercial kitchen pass-through ventilation, and external wall termination points. Their steel construction makes them significantly more robust and vandal-resistant than aluminium alternatives.

What sizes are available?

We stock 9 standard square sizes: 150×150mm, 200×200mm, 250×250mm, 300×300mm, 350×350mm, 400×400mm, 450×450mm, 500×500mm and 600×600mm. All are square format with the size referring to the aperture or duct opening dimension. If you need a rectangular format or a non-standard size, get in touch — we can source bespoke pressed steel grilles to order.

Can pressed steel grilles be used externally?

Yes. Our pressed steel grilles are suitable for both internal and external applications. The powder-coated finish provides weather protection, and the steel construction handles exposure better than lightweight aluminium grilles. For external use they're commonly fitted as wall termination points for extract ductwork, plant room intake or exhaust openings, and ventilation openings in car park structures. For exposed coastal or high-humidity environments, check whether a stainless steel or additional galvanised option would be more appropriate — call us on 0161 818 2050 to discuss.

What is the difference between a pressed steel grille and a deflection grille?

Pressed steel grilles have fixed blades at a set angle — you can't adjust the direction of airflow. They're built for durability and simplicity, not airflow control. A single deflection grille has adjustable blades in one plane (horizontal or vertical), and a double deflection grille has adjustable blades in both planes, giving full control over air direction and spread. Use deflection grilles where you need to direct conditioned supply air precisely (offices, meeting rooms). Use pressed steel grilles where you just need air to get through a wall or door opening with a robust, low-maintenance finish.

What does 67% free area mean?

Free area is the percentage of the grille face that is open to airflow — the rest is taken up by the blade material and frame. At 67%, roughly two-thirds of the grille surface allows air to pass through. That's a good balance between airflow capacity and the structural strength needed from a steel grille. For comparison, an egg crate grille offers around 90% free area (better for high-volume extract), while a double deflection grille typically provides 60–80%. When sizing a pressed steel grille, your ventilation engineer will calculate the required free area based on the duct velocity and volume flow rate to ensure the grille doesn't create excessive pressure drop or noise.

Can I fit a pressed steel grille in a fire-rated door or wall?

A pressed steel grille alone does not provide a fire rating. If the wall or door is part of a fire compartment, Building Regulations Part B requires that any penetration maintains the fire resistance of the element. That means you'll typically need a fire damper or intumescent grille behind or in place of the standard pressed steel grille. Intumescent grilles expand when exposed to heat and seal the opening, maintaining compartmentation. If you need to ventilate through a fire-rated wall or door, contact us and we can advise on the right combination of grille and fire protection for your specific application.