High-security double glazing

High-security double glazing puts a forced entry rating inside a thermally efficient sealed unit. The security laminate sits within the double or triple glazed build up, so the window keeps heat in while resisting attack. ArxBridge supplies and installs rated glazed units across the UK for commercial and residential projects.

• Rated sealed unitsSecurity laminate in the build up
• Double and tripleGlazed to suit the frame
• LPS 1175 optionsTested with the window system
• UK wideSurvey, supply and installation

About high-security double glazing

A high-security double glazed unit is a sealed unit whose laminate has been tested as part of a rated window system. Two or three panes of glass are bonded around a spacer bar with a sealed cavity, and one or more of the panes is a laminated security glass. The unit insulates like normal double glazing and resists attack like security glass.

The important point is that the unit on its own carries no rating. The LPS 1175 rating belongs to the complete window: frame, unit, beads and hardware tested together. The sealed unit is manufactured to the specification of that tested system, so the glass, the cavity and the edge seal all match what was proven in the test.

Triple glazed units add a third pane and a second cavity. They suit projects chasing lower heat loss, and the extra pane gives more room in the build up for thicker security laminates. The weight rises with each pane, so the frame and hardware must be specified for the heavier unit.

Which rating do you need for high-security double glazing

Choose the unit build up to match the rating of the window system it sits in. The glass must never be the weak point of the assembly.

The LPS 1175 ratings guide sets out the full scale from A1 (SR1) to H20 (SR8). For homes, PAS 24 remains the common baseline, pitched at a lower threat level than LPS 1175.

Specifier note. A security laminate ordered as a standalone sealed unit has no rating. Always order the unit as part of the tested window system, with test evidence for the exact configuration.

Construction of high-security double glazing

Manufacture starts with the laminate: layers of glass bonded with interlayers that hold the pane together under attack. The laminated pane is then built into the sealed unit with the spacer bar, the cavity gas fill and the edge seals. The unit is only as good as its edge, because an attacker who can reach the edge of the glass can work on the bond to the frame.

The unit is bedded into the security window frame with security tapes or compounds and retained by beads that resist removal from outside. Internal beading is the norm for rated work: if the beads can only be reached from inside, the glass cannot be stripped out from the street.

Thermal performance is designed at the same time. Cavity width, gas fill and low emissivity coatings set the heat retention, while the laminate sets the security level. The two are balanced in the specification so neither compromises the other.

Combining high-security double glazing with other ratings

Where the threat includes blast, the sealed unit can be engineered as part of a blast resistant window system, where the laminate holds fragments and the frame absorbs the pressure. Where firearms are the concern, glazing rated to the BR classes of EN 1063 replaces the standard laminate, as used in bullet resistant glass installations.

For existing windows that cannot be replaced, blast protection window film applied to the glass is a retrofit option. It does not give a forced entry rating, but it holds fragments together and it suits buildings where the frames must stay.

Where to use high-security double glazing

Residential and housing projects use high-security double glazing at ground floor and accessible levels, where the unit must insulate and protect at the same time. Education buildings use it at ground floor classrooms, where thermal comfort and resistance to break in attempts are both daily concerns.

Commercial offices, healthcare buildings and retail units use rated sealed units wherever the facade is extensively glazed. Plant rooms and records stores, which need fewer windows, get the higher rated build ups because the contents justify them. The Security range covers the windows, doors and glazing for all of these applications.

What sets the cost and lead time for high-security double glazing

Laminate weight is the main driver: heavier interlayers and thicker glass cost more and need deeper frames. Triple glazed units cost more than double glazed at the same security level, and large panes need handling equipment on site. Any acoustic or solar control coating in the build up adds manufacture time.

Because the unit must match a tested window system, the choice of system narrows the suppliers and can extend lead times for unusual sizes. Retrofit replacement of units into existing frames is only possible where the frame can take the weight and depth of the rated unit, which the survey will confirm. A schedule of unit sizes and the target rating are the basis for a quotation.

How to specify high-security double glazing

1. Name the window system first. The unit is specified as part of a tested assembly, never alone.
2. Set the rating. Match the unit build up to the LPS 1175 rating of the window.
3. State the thermal target. Confirm the heat retention the project needs from the sealed unit.
4. List coatings and tints. Solar control, acoustic layers and any manifestation for large panes.
5. Confirm the test evidence. Ask for third party evidence covering the exact unit and frame combination.
6. Request a firm quotation. Send drawings and the glazing schedule for a fixed proposal.

Frequently asked questions