What is a roller shutter?

A roller shutter is a curtain of hinged slats that runs down guide rails in front of a window or door and coils onto a barrel at the top. It combines four functions that would otherwise each need their own solution: solar shading, blackout, extra insulation and burglary delay.

Versions

• Surface-mounted (built-on) shutter — the box sits visibly outside, above the window. The most common option in refurbishment, because no building work is needed.
• Front-mounted box with a chamfered or rounded face — neater in the elevation, often painted to match.
• Built-in shutter — the box is concealed behind the masonry or within the frame and is barely visible outside. Only sensible in new build or when replacing windows.
• Screen — a fabric blind instead of slats; it stops solar heat while retaining light and a view out.

Materials

Slats are usually roll-formed aluminium with a rigid foam filling, or PVC. Foam-filled aluminium is stronger and holds its shape better; PVC is cheaper and mainly used in lighter applications. For security there are heavier slats and versions with additional locking into the guide rails.

What a roller shutter delivers

• Solar shading — the great advantage of external shading is that the heat stays outside. Internal blinds let the radiation through the glass, and that heat is then already indoors.
• Insulation — a closed shutter creates a still air layer in front of the glass. The effect is noticeable, particularly with single glazing and older double glazing, but it is no substitute for good glazing.
• Blackout and sound — close-fitting slats make a bedroom genuinely dark and damp traffic noise somewhat.
• Burglary delay — a closed, locked shutter is visibly awkward and costs time. If you intend to rely on it, specify a tested security-rated version; a standard shutter is not one.

Points to watch

1. Thermal bridging at the box. Older built-in boxes leak heat to the outside. On a new box, ask about its insulation and about an airtight internal seal.
2. Operation. Strap, crank or electric. Motorising is straightforward to retrofit and close to essential on high or awkward windows. With motors, make sure there is a manual override for a power cut.
3. Escape routes. A shutter that cannot be opened during a power cut blocks an escape route — a genuine issue on bedroom windows.
4. Consent. On a listed building or in a conservation area an externally visible shutter usually needs consent. Check with the local authority first.
5. Maintenance. Keep the guides clean, check the slats for play and the strap for wear. A sticking shutter is almost always a dirty or distorted guide rail.

Related terms

• Awning
• Roller door
• Security bars
• Window frame
• Anti-burglar hardware

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