Security double-glazed units

What are security double-glazed units?

A security double-glazed unit is a sealed unit in which one or both panes are laminated glass, usually the inner pane, so the window keeps its insulation but resists being broken through. It fits the same frame as a standard unit and is the simplest way to add security to modern windows and doors.

In a standard unit both panes are often annealed or toughened glass, and once they are broken the gap is open. With a laminated inner pane, smashing the outside achieves little: the inner pane cracks but holds, and getting through it takes time and noise. A typical makeup is a 4 mm toughened outer pane, a spacer bar with argon gas, and a 6.4 or 6.8 mm laminated inner pane, built to the same overall thickness as your current units where possible.

Units are made to measure for each sash or door panel. Thicker or heavier units may need different beads, packers or hinge adjustment, and some door glazing comes as a cassette from the door's maker. We check the frame, the glazing rebate and whether the beads are inside or outside before ordering, because a strong unit held in by beads that can be prised off from outside is not much of an upgrade.

How much do security double-glazed units cost?

Our guide range is £174 to £594 including VAT (£145 to £495 plus VAT) per unit, supplied and fitted. The exact figure depends on size, glass makeup, frame condition and access, and your fixed price is confirmed in writing after the free survey. See all glass prices.

Specification and options

Laminated inner pane, outer pane or both
Toughened outer pane where safety glass is required
Low-E coating and argon fill for insulation
Warm-edge spacer bars in black, grey or white
24 mm, 28 mm and other overall thicknesses to suit frames
Obscure and decorative glass for bathrooms and doors
Security glazing tape or clips where beads are external
Made to measure for each sash, light and door panel

Where security double-glazed units are used

Ground-floor and basement windows
Glazed back and side doors
Patio doors and bifolds
Windows in flats on walkways and balconies
Replacing misted or damaged units

What to decide before you order

Which pane is laminated

Laminating the inner pane is the usual security choice. Laminating both panes adds protection on high-risk elevations.

Overall thickness

The new unit must suit the frame's glazing rebate. If your frames only take thin units, we use thinner laminates or adjust the beads.

Internal or external beads

If your beads are on the outside, we add security tape or clips so the unit cannot be lifted out after the beads are removed.

Energy performance

Choosing low-E glass, argon and warm-edge spacers keeps the window as efficient as possible, often better than the unit being replaced.

Rules across the UK

Safety glazing, building regulations, planning and listed building rules differ between England, Wales, Scotland and Northern Ireland. These are the points most relevant to security double-glazed units; local pages show the version for your nation.

England (similar principles apply in Wales, Scotland and NI)

Replacing glass in an existing frame

Replacing only the glass or sealed unit in an existing frame is generally treated as a repair in England rather than notifiable building work. Replacing a whole window or door is notifiable and is normally certified through a competent person scheme or approved by building control. Either way, new glass in a critical location should still be safety glass.

Safety glass in critical locations

In England, section 5 of Approved Document K treats glazing in doors and in side panels within 300 mm of a door edge, from floor level up to 1,500 mm, and any other glazing below 800 mm, as a critical location. Glass there should break safely, be robust, or be guarded. Laminated or toughened glass meeting BS EN 12600 class 3 is the usual answer, rising to class 2 for door and side-panel panes wider than 900 mm.

Security rules for new homes

Approved Document Q has applied to new homes in England since 1 October 2015. Easily accessible doors and windows, meaning any part within 2 m vertically of the ground or another accessible surface, should meet PAS 24 or an equivalent, and glazing in doors and in windows within 400 mm of a door should be laminated to at least BS EN 356 P1A. It does not apply when you change the glass in an existing home, although it is a sensible benchmark.

How it works

Tell us what needs securing

Use the guide price tool or form, or call. Pane sizes and a few photos help us give a guide figure straight away.

Free survey

A surveyor measures each pane, checks the existing glass, frame and beads, and talks through the rating that suits the risk.

Fixed price in writing

You get a written quote listing each pane, the glass type and class, the price and the lead time. Nothing is ordered until you accept.

Made to measure and fitted

Glass is made to order and fitted by glaziers working under our contract with you, then cleaned, checked and explained.

Security double-glazed units: questions

How much does a security double-glazed unit cost?

Most security double-glazed units cost from £145 to £495 plus VAT (£174 to £594 inc VAT) supplied and fitted, depending on size, the laminate used and the glass finish. Larger patio and door units cost more. Your fixed price follows a free survey.

Can I just replace the glass and keep my frames?

Yes, if the frames are sound. We measure each unit, make security units to the same size and fit them into your existing frames.

Which pane should be laminated?

Usually the inner pane, so smashing the outer pane does not create an opening. On doors and low panes the outer pane is normally toughened to meet safety rules.

Will a laminated unit be heavier?

A little. A laminated pane weighs about the same as a solid sheet of the same thickness. On large opening sashes we check hinges and friction stays.

Do security units reduce noise?

Laminated glass already damps sound better than plain glass, and acoustic interlayers improve it further, which helps on busy roads.

How long do new units take?

Units are made to order after the survey. Lead times vary with glass type and size, and we confirm them when we quote.

Find security double-glazed units near you

Choose your county or region for local information and the rules that apply where you are.

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