{"product_id":"triple-glazed-safety-toughened-laminated-unit","title":"Triple Glazed Safety Unit (Toughened + Laminated)","description":"\n\u003cp class=\"pr-flagship__lede\"\u003e\u003cstrong\u003eThe triple-glazed unit for critical locations and overhead glazing\u003c\/strong\u003e. A triple-glazed sealed unit with toughened outer and inner panes plus a laminated middle pane combines Approved Document N safety compliance with Approved Document L thermal performance — and adds the BS 5516 overhead-glazing safety requirement that vanilla toughened triple cannot meet.\u003c\/p\u003e\n\n\u003cp\u003eFor most replacement windows, a 28mm toughened double is the standard safety spec. But where the application demands triple-glazed thermal performance AND involves overhead glazing (conservatory roof bars, atria, balcony glazing, large-span domestic rooflights), the safety regime escalates: both BS 5516 (overhead glazing) and Approved Document N (impact safety) need to be satisfied at once. This flagship is engineered for that intersection.\u003c\/p\u003e\n\n\u003ch2\u003eWhy toughened + laminated, not toughened alone\u003c\/h2\u003e\n\u003cp\u003eToughened glass is impact-strong but failure-mode-dangerous overhead. When toughened breaks, it shatters into thousands of granular fragments — relatively safe at low elevation, but a hazardous shower from height. BS 5516 (overhead glazing code of practice) requires that overhead panes either be laminated (so fragments stay in the interlayer) or be supported by a secondary catchment system.\u003c\/p\u003e\n\n\u003cp\u003eThis unit places the laminated pane as the middle pane in the triple stack. The outer and inner toughened panes provide impact strength; if both break, the laminated middle layer holds glass fragments in place — meeting BS 5516 without compromising the impact-rated outer\/inner faces.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical specification\u003c\/h2\u003e\n\u003ctable class=\"pr-spec-table\"\u003e\n  \u003ctr\u003e\n\u003cth\u003eOverall thickness\u003c\/th\u003e\n\u003ctd\u003e36-40mm depending on laminated mid-pane spec\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eBuild-up\u003c\/th\u003e\n\u003ctd\u003e4mm toughened \/ 12mm argon \/ 6.4mm laminated middle (3+3 with 0.38mm PVB) \/ 12mm argon \/ 4mm toughened\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eCavities\u003c\/th\u003e\n\u003ctd\u003e2 × 12mm argon-filled (BS EN 1279-3)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eOuter\/Inner impact classification\u003c\/th\u003e\n\u003ctd\u003eBS EN 12150 + BS EN 12600 Class 1(C)1\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eMiddle pane standard\u003c\/th\u003e\n\u003ctd\u003eBS EN 14449 laminated (PVB interlayer)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eOverhead-glazing compliance\u003c\/th\u003e\n\u003ctd\u003eBS 5516 (laminated middle satisfies fragment-retention requirement)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (centre-pane, with low-E)\u003c\/th\u003e\n\u003ctd\u003e0.8 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (uncoated)\u003c\/th\u003e\n\u003ctd\u003e1.0 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eg-value\u003c\/th\u003e\n\u003ctd\u003e0.54\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eLight transmittance\u003c\/th\u003e\n\u003ctd\u003e~70%\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd\u003e~35 kg\/m² (heavy — confirm structural frame capacity)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eStandards\u003c\/th\u003e\n\u003ctd\u003eBS EN 1279, BS EN 12150, BS EN 14449, BS 5516, Approved Document N, Approved Document L\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eWhere this unit is the right call\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eConservatory roof bars and triangular vents\u003c\/strong\u003e where overhead glazing must comply with BS 5516 AND the room is thermally connected to the dwelling (so Part L applies).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLarge-span rooflights\u003c\/strong\u003e in domestic extensions — typically anything \u0026gt;2m² overhead requires laminated under BS 5516.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAtrium glazing and pitched balcony screens\u003c\/strong\u003e where falls from height create a foreseeable risk.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFrench doors and floor-to-ceiling glazing in critical locations\u003c\/strong\u003e needing both impact safety (Class 1(C)1) AND triple-pane thermal performance for Passivhaus\/EnerPHit specs.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBath-screen glazing in high-traffic family bathrooms\u003c\/strong\u003e — where both fragment retention and impact resistance matter at the door edge.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSchool and hospital glazing\u003c\/strong\u003e in critical locations under public-sector safety procurement frameworks.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe full safety-glazing decision tree, including the laminated-vs-toughened tradeoffs and the anti-bandit upgrade path, is on the \u003ca href=\"\/pages\/safety-security-glass\"\u003e\u003cstrong\u003esafety \u0026amp; security glass topical page\u003c\/strong\u003e\u003c\/a\u003e. For non-overhead critical locations where double glazing thermal is adequate, the simpler \u003ca href=\"\/products\/28mm-safety-toughened-double-glazed-unit\"\u003e28mm Safety Toughened Double Glazed Unit\u003c\/a\u003e is the cost-optimal choice.\u003c\/p\u003e\n\n\u003ch2\u003eStock sizes and pricing\u003c\/h2\u003e\n\u003cp\u003eFive UK-standard stock sizes are below. Dispatch 14-18 working days (toughening + lamination + triple assembly is a sequential multi-stage process). Custom sizes — including arched-top rooflight units, shaped balustrade panels, and Class 2(B)2 upgraded impact-rated builds — are priced via the \u003ca href=\"\/pages\/configure\"\u003e\u003cstrong\u003econfigurator\u003c\/strong\u003e\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eFrame load note:\u003c\/strong\u003e at ~35 kg\/m² this unit is roughly 75% heavier than a 24mm DG. Confirm structural-frame capacity, fixing-bolt spec, and hinge ratings. For overhead-glazing applications, structural-engineer sign-off on the supporting framework is usually required.\u003c\/p\u003e\n\n\u003ch2\u003eCertification and standards\u003c\/h2\u003e\n\u003cp\u003eEvery unit ships with: UKCA mark, BS EN 1279 Declaration of Performance, BS EN 12150 toughening stamp permanently etched in two corners, BS EN 14449 laminated-glass certificate on the middle pane, and a BS 5516 overhead-glazing compliance statement on request. Heat-soak testing (BS EN 14179) on the toughened panes is available as a build option for large-span overhead applications where spontaneous breakage risk warrants it.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003ch3\u003eIs laminated alone good enough overhead?\u003c\/h3\u003e\n\u003cp\u003eLaminated meets BS 5516 fragment-retention on its own — but it doesn't necessarily meet Approved Document N impact classification. For critical locations under or near doors, a Class 1(C)1 impact rating is required. This flagship's outer\/inner toughened faces deliver that; the laminated middle adds the overhead fragment-retention. Both standards satisfied in one stack.\u003c\/p\u003e\n\n\u003ch3\u003eWhy not laminated outer AND inner?\u003c\/h3\u003e\n\u003cp\u003eYou could specify that — and it would meet both standards with a different tradeoff (slightly higher Rw acoustic, slightly lower impact rating, ~£15-20\/m² more). The toughened-outer-toughened-inner-laminated-middle build is the cost-optimal route for the typical critical-location-plus-overhead intersection. The configurator surfaces both options if you want to A\/B them.\u003c\/p\u003e\n\n\u003ch3\u003eCan the middle pane be heat-strengthened instead of laminated?\u003c\/h3\u003e\n\u003cp\u003eHeat-strengthened is between annealed and toughened in strength — it has a wider fragment pattern than toughened but doesn't reliably retain fragments. It does not satisfy BS 5516 overhead-glazing requirements. The PVB-laminated middle is the standards-compliant choice.\u003c\/p\u003e\n\n\u003ch3\u003eSpontaneous breakage with toughened — risk?\u003c\/h3\u003e\n\u003cp\u003eNickel-sulphide inclusion-driven spontaneous breakage occurs at roughly 1 per 8 tonnes of float feedstock. For large-span overhead applications (\u0026gt;4m² rooflights, balustrade-adjacent), specify heat-soak-tested toughened (BS EN 14179) — adds ~£8\/m² and reduces NiS risk by \u0026gt;99%. For most domestic-scale critical locations, untreated toughened is the standard.\u003c\/p\u003e\n\n\u003ch3\u003eHow does this fit in a conservatory roof?\u003c\/h3\u003e\n\u003cp\u003eModern aluminium conservatory roof systems (e.g., Eurocell Skyroom, Ultraframe Livinroof) are profiled for 28-40mm units. Confirm with the system supplier — most accept 36-40mm. Older PVCu conservatory roofs may need profile upgrade or full re-roof.\u003c\/p\u003e\n\n\u003ch3\u003eBuilding Control sign-off?\u003c\/h3\u003e\n\u003cp\u003eLocal Authority Building Control or Approved Inspectors will check that critical-location glazing meets Approved Document N (impact) and overhead glazing meets BS 5516 (fragment retention). The DoP and impact-class certificate that ship with each unit are typically sufficient for sign-off. We can supply Letter of Conformance for tender \/ commercial projects.\u003c\/p\u003e\n\n\u003ch3\u003eWarranty?\u003c\/h3\u003e\n\u003cp\u003e10 years on edge-seal integrity. 10 years on argon retention to ≥80% of initial fill. 10 years on PVB delamination (BS EN 14449). Toughened pane integrity is a manufacturer's lifetime warranty against in-stock defect — spontaneous breakage from NiS inclusion is excluded unless heat-soak-tested is specified at order.\u003c\/p\u003e\n","brand":"Pane Relief","offers":[{"title":"600 × 400 mm","offer_id":61853204054346,"sku":"TG-SAFTL-600x400","price":45.0,"currency_code":"GBP","in_stock":true},{"title":"800 × 600 mm","offer_id":61853204087114,"sku":"TG-SAFTL-800x600","price":88.0,"currency_code":"GBP","in_stock":true},{"title":"1000 × 800 mm","offer_id":61853204119882,"sku":"TG-SAFTL-1000x800","price":147.0,"currency_code":"GBP","in_stock":true},{"title":"1200 × 1000 mm","offer_id":61853204152650,"sku":"TG-SAFTL-1200x1000","price":220.0,"currency_code":"GBP","in_stock":true},{"title":"1500 × 1200 mm","offer_id":61853204185418,"sku":"TG-SAFTL-1500x1200","price":330.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/3515\/2458\/files\/triple-glazed-insulated-glass-unit-igu-cutaway_cbb6e68f-bcbb-4c8e-9f14-92d931972e83.webp?v=1779007268","url":"https:\/\/panerelief.co.uk\/products\/triple-glazed-safety-toughened-laminated-unit","provider":"Pane Relief","version":"1.0","type":"link"}