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Passive Ventillation : Louvre Panels

Louvre panels generally consist of these components:

  • Frame - either flanged frame or glazed-in frame form the outside of the louvre panel and dictate the overall panel size.

  • Blades - these make-up the body of the louvre and sit inside the frame. We offer standard “Z” profile blades in 33mm, 50mm and 75mm pitch format, and “V” profile blades in 50mm pitch format. “V” profile blades are used when a higher degree of weatherproofing is required

  • Clips - these fix into the side frames and hold the blades in position

  • Mullion - this is an additional vertical support for louvres over a certain width

  • Mesh - this prevents birds or insects from getting through a louvre in the space between blades. Typically this is made from Nylon Fibre, Stainless Steel or aluminium

  • Drip sill - sometimes fitted to take water away from the lower edge of the louvre if it is installed in a harsh weather environment e.g. Sea-front applications.

  • Back panel - sometimes fitted to allow the attachment of extraction ducting, generally in a plant room or similar installation. Typically this is fabricated from 1.6mm sheet aluminium, cut to fit. Also available fitted with a variety of insulation options.

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Flanged frame

Sometimes known as “odd leg” or “picture” frame, this is designed so that the main body of the louvre sits within the aperture, with a flange around the outside to allow front fixing. Optionally concealed fixing is possible with the use of internal straps.

Glazed-in frame

The more common form of louvre frame, it consists of either 24 mm or 28 mm glazing channel to allow installation in curtain walling or other building envelope systems.


The pitch of a louvre is the measurement in mm between the top of one louvre blade and the top of the next louvre blade down. The pitch is one of the measurements that affects the free area of a louvre.

Plant room

An entire plant room can be constructed using continuous louvre wall, alternatively glazed in panel louvres can be used to provide ventilation. If the whole plant room is created using continuous louvre wall, then louvre doors are usually included as part of the package.

Free area

The free area measurement of a louvre is used to indicate the amount of space available for air to pass through in any given louvre type. It is a mathematical calculation, based on the size, shape and positioning of the louvre blades in the louvre panel.

As a general guide, the greater the pitch louvre blades, the greater the free area of a louvre panel. A panel made from 33 mm pitch blades typically gives a free area of 35% - 45%, whereas a 100 mm pitch louvre system may provide in excess of 65%.

Other factors that will effect the free area figure include the blade profile (“Z” or “V”) and the type and density of mesh on the back of the louvre.

If you'd like to discuss your project, please call: 01455 848300 or contact us