Composite Door Glass Insert

The replacement insert for composite front doors. A 24mm sealed unit combining a toughened outer pane (BS EN 12150) with a laminated inner pane (BS EN 14449), argon-filled cavity, sized for the small-format glass inserts typical of UK composite front doors — 285 to 600mm wide, 850 to 1200mm tall. Toughened-plus-laminated is the spec composite-door manufacturers default to, because it combines critical-location impact safety with light intruder resistance in one stack.

Composite front doors are the dominant UK front-door type post-2010: a high-density polyurethane core sandwiched between GRP (glass-reinforced polymer) skins, with cut-outs for glazed inserts and letter-plates. When the glass insert fails — typically misting or seal blow after 8-15 years — the door itself is usually fine, only the unit needs replacement. This flagship handles the standard composite-door insert sizes used by the major UK door brands.

Why toughened outer + laminated inner

The composite-door insert sits at adult-shoulder-to-knee height in a high-traffic family entrance. Approved Document N classifies it as a critical location: glazing within 300mm of a door edge, below 1500mm, must meet Class 1(C)1 (toughened) or Class 2(B)2 (laminated equivalent). The toughened outer satisfies this on the outside face.

The laminated inner adds two things: (a) light intruder resistance — the PVB interlayer prevents a clean break-through after the outer toughened layer is shattered, slowing forced entry meaningfully; (b) fragment retention on the inside face — if a child or pet impacts the door from the inside, the toughened-shattering shower is contained by the laminated layer. Both together is the standard spec for "secure by design" residential entrance glazing.

Technical specification

Where this unit is the right call

• Replacement of failed (misted, blown, condensated) glass inserts in UK composite front doors — the standard application. Original door is usually fine; only the unit needs replacing.
• Solidor, GRP-Tech, Hurst, Endurance, Distinction Doors and other major UK composite-door brand inserts — most accept 24mm units in the cut-out. Check brand-specific bead sizes before ordering.
• Approved Document Q compliance for new-build entrance doors — Part Q requires "secure by design" front-entrance glazing on new dwellings. Toughened-plus-laminated is the standard compliant build.
• Higher-risk security postcodes — areas with elevated burglary rates where the homeowner wants more than standard toughened. (For high-risk applications, consider upgrading to BS EN 356 P-rated anti-bandit via configurator.)
• Period-property front doors retrofitted with composite-door cores but retaining a glazed sidelight or insert with heritage muntin overlay — internal Georgian bars are configurable.

For French door replacement units (single-leaf 600-900mm wide), the French Door Glass Sealed Unit (Symmetric Pane) flagship is the right spec. For full-height patio / bi-fold door glazing, the Patio / Bi-Fold Door Glass Unit (Triple Glazed) flagship handles that aperture range. The full safety-glazing decision tree is on the safety & security glass topical page.

Stock sizes — composite-door-insert-specific

Four standard composite-door insert stock sizes are listed below — covering the most common cut-out sizes used across the major UK composite-door brands:

• 285 × 850 mm — narrow letterbox-pane insert (Solidor "Italia" range, similar narrow patterns)
• 285 × 1200 mm — tall slim insert pattern (Solidor "Conway", Hurst "London")
• 400 × 1000 mm — typical mid-size insert (Endurance, Distinction Doors common patterns)
• 600 × 1200 mm — full-width insert (modern minimal "single-glazed-look" composite doors)

Dispatch 10-14 working days from order (toughening + lamination + sealed-unit assembly is a sequential multi-stage process). Custom sizes — including circular and elliptical inserts (popular in cottage-style composite doors), shaped Gothic-top inserts, and brand-specific bespoke replicas — are priced via the online glass configurator. Send a photo of the door brand badge or product label at order — many composite-door brands have their own glass-pattern signature that we can replicate (frosting, sandblast pattern, internal bar layout).

Pattern and decoration: most composite-door inserts in service feature a decorative pattern — frosted geometric, sandblasted floral, bevelled clear, or stained-leadlight overlay. We supply with standard clear by default; configure the configurator with pattern options or upload a reference photo for bespoke matching. Pattern matching adds 5-7 working days.

Certification and standards

Every unit ships with: UKCA mark, BS EN 1279 Declaration of Performance, BS EN 12150 toughening stamp etched on the outer pane, BS EN 14449 laminated-glass certificate on the inner pane (PVB batch identity included), BS EN 12600 impact classification, and an Approved Document Q compliance statement on request (relevant for new-build sign-off). For commercial / multi-residential projects, we supply a Letter of Conformance referencing the standards bundle.

Frequently asked questions

Which composite-door brands are these compatible with?

The 4 stock sizes cover ~80% of UK composite doors from Solidor, Endurance, Hurst, Distinction Doors, GRP-Tech, Rockdoor, and Comp Door. Bead-size tolerance is typically ±2mm — most brands accept the standard 24mm overall thickness. The remaining ~20% are bespoke / boutique brands with proprietary insert sizes; for those, custom-size configuration is the right path. Send a brand identifier + photo when ordering custom.

Will it fit my existing composite-door cut-out?

Measure the existing unit (gentle measurement at the rebate after carefully removing the inner bead if accessible). The replacement should match the existing unit's overall dimensions within 2-3mm — the cut-out is sized for the unit, not the unit for the cut-out. Send dimensions + a door brand identifier to our contact form for fit confirmation before ordering.

How secure is this vs standard toughened DG?

Meaningfully more secure. A burglar attacking standard toughened double glazing with a brick or hammer typically gets through in 5-10 seconds (the granular shower clears the aperture quickly). The laminated inner pane on this unit holds glass fragments in place after the toughened outer breaks — typically extending the forced-entry time to 60-120 seconds, long enough for alarms to deter opportunistic intruders. For high-risk applications, specify BS EN 356 P-rated anti-bandit via the configurator.

UV blocking — actually meaningful?

Yes for hall furnishings near a sun-facing front door. PVB blocks ~99% of UV-A and UV-B (vs ~30% UV-A for monolithic glass). Halls with east-facing or south-facing front doors see hall-runner fade, console-table colour-shift, and printed-artwork degradation reduced markedly with laminated glazing on the door insert. The UV benefit is essentially a side-effect of the safety/security spec but worth knowing.

Can I get a frosted or bevelled pattern?

Yes — frosted, sandblasted, satin-acid-etch, and bevelled-clear patterns are configurable. Bevelled clear is the most popular for modern minimalist composite doors; sandblasted floral and Georgian-bar overlays are common in cottage and traditional ranges. Configure via the configurator with brand and pattern photo for bespoke matching.

Lead time for stock sizes?

10-14 working days. Toughening adds 3 days, lamination adds 3-5 days, sealed-unit assembly adds 2-3 days — these are sequential processing steps, not parallel. Heat-soak testing (BS EN 14179) on the toughened outer adds another 3 days; recommended for high-risk applications where spontaneous breakage of a previously-replaced toughened unit nearby has been observed.

Warranty?

10 years on edge-seal integrity (BS EN 1279-2). 10 years on argon retention to ≥80% of initial fill. 10 years on PVB delamination (BS EN 14449 manufacturer standard). Toughened pane integrity is manufacturer-lifetime warranty against in-stock defect; spontaneous NiS-inclusion breakage is excluded unless heat-soak-tested. Transit damage is covered for 14 days from delivery — inspect on receipt before installer signs off.