{"product_id":"specialist-acoustic-laminated-glass-asymmetric-double-glazed-unit","title":"Specialist Acoustic Laminated Double Glazed Unit (8.8 + 4mm Asymmetric)","description":"\n\u003cp class=\"pr-flagship__lede\"\u003e\u003cstrong\u003eThe cost-optimal acoustic flagship — Rw 40 dB in a 28mm double-glazed envelope\u003c\/strong\u003e. An asymmetric double-glazed unit with an 8.8mm acoustic-PVB laminated outer pane and a 4mm clear inner, separated by a 14mm argon-filled cavity, delivers acoustic performance previously only available from triple glazing — at roughly half the cost and weight.\u003c\/p\u003e\n\n\u003cp\u003eFor most urban-noise-mitigation projects, this is the right unit. It fits standard 28mm double-glazed rebates, weighs about 23 kg\/m² (not the 38 kg\/m² of acoustic triple), and achieves an Rw of 40 dB — a 10-12 dB improvement over a typical 1990s 4-12-4 double. The perceived loudness reduction is roughly halving — traffic that previously dominated a room moves into the background.\u003c\/p\u003e\n\n\u003ch2\u003eAsymmetric build — why it works\u003c\/h2\u003e\n\u003cp\u003eSymmetric double-glazed units (4-12-4, 4-20-4) have a coincidence-frequency dip where the two identical panes resonate together. Sound at that frequency punches through. Replacing one pane with a thicker laminated build shifts the coincidence frequency of that pane to a different band — so the two panes' dips no longer coincide.\u003c\/p\u003e\n\n\u003cp\u003eThe acoustic PVB interlayer in the 8.8mm laminate adds viscoelastic damping. Standard PVB (used in safety lamination) helps mildly. Acoustic-grade PVB (e.g., Trosifol SC, Saflex Q) is engineered with specific viscoelastic properties tuned to road and rail frequency bands — it absorbs 3-5 dB more than standard PVB across the critical 500-2500 Hz range.\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\u003e~28mm\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eBuild-up\u003c\/th\u003e\n\u003ctd\u003e8.8mm acoustic-laminated outer (4+4 with 0.76mm acoustic PVB) \/ 14mm argon cavity \/ 4mm clear inner with optional low-E\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eOuter-pane standard\u003c\/th\u003e\n\u003ctd\u003eBS EN 14449 (laminated)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eR\u003csub\u003ew\u003c\/sub\u003e (Weighted Sound Reduction Index)\u003c\/th\u003e\n\u003ctd\u003e40 dB to BS EN ISO 717-1\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eR\u003csub\u003ew\u003c\/sub\u003e + C\u003csub\u003etr\u003c\/sub\u003e (road-traffic spectrum)\u003c\/th\u003e\n\u003ctd\u003e36-37 dB (typical)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (centre-pane, with low-E inner face 3)\u003c\/th\u003e\n\u003ctd\u003e1.2 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (without low-E)\u003c\/th\u003e\n\u003ctd\u003e1.5 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eg-value\u003c\/th\u003e\n\u003ctd\u003e0.58\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eLight transmittance\u003c\/th\u003e\n\u003ctd\u003e~78%\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd\u003e~23 kg\/m² (manageable load in standard frames)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eStandards\u003c\/th\u003e\n\u003ctd\u003eBS EN 1279, BS EN ISO 717-1, BS EN 14449, BS EN 12600 (impact class 2(B)2 via laminated)\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\u003eUrban frontage facing busy A-roads, ring roads, or town-centre traffic\u003c\/strong\u003e — typical existing R\u003csub\u003ew\u003c\/sub\u003e 28-30 dB, upgrading to 40 dB roughly halves perceived noise.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eProperties within 200m of a railway line\u003c\/strong\u003e — particularly Network Rail main lines, freight routes, and HS2\/Crossrail corridors. Asymmetric stacks handle low-frequency rail noise better than symmetric.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlight-path properties outside the 60 dB L\u003csub\u003eAeq,16h\u003c\/sub\u003e contour\u003c\/strong\u003e where R\u003csub\u003ew\u003c\/sub\u003e 40 typically delivers an acceptable internal noise level without needing the cost\/weight of acoustic triple.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eApartment buildings and HMOs\u003c\/strong\u003e where Approved Document E (sound insulation between dwellings) compliance crosses with external glazing performance.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBoutique hotels and serviced apartments\u003c\/strong\u003e where guest noise expectations drive specification.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHome offices and recording studios\u003c\/strong\u003e in urban areas where noise floors below ~35 dB are the target.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe full acoustic-glass guide, including the R\u003csub\u003ew\u003c\/sub\u003e vs R\u003csub\u003ew\u003c\/sub\u003e+C\u003csub\u003etr\u003c\/sub\u003e distinction, frame-seal advice, and acoustic trickle-vent guidance, is on the \u003ca href=\"\/pages\/acoustic-glass\"\u003e\u003cstrong\u003eacoustic glass topical page\u003c\/strong\u003e\u003c\/a\u003e. For the highest-performance acoustic spec (44 dB Rw triple-glazed), see the \u003ca href=\"\/products\/triple-glazed-acoustic-unit-44db-rw\"\u003eTriple Glazed Acoustic flagship\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch2\u003eStock sizes and pricing\u003c\/h2\u003e\n\u003cp\u003eFive UK-standard stock sizes are below. Dispatch 10-14 working days (acoustic-PVB lamination adds ~5 days to standard DG manufacturing). Custom sizes — including shaped, oversized, and bespoke pane-asymmetry builds (e.g., 8.8 + 6.4 for max-mass at boundaries) — are priced via the \u003ca href=\"\/pages\/configure\"\u003e\u003cstrong\u003econfigurator\u003c\/strong\u003e\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch2\u003eCertification and standards\u003c\/h2\u003e\n\u003cp\u003eEvery unit ships with: UKCA mark, BS EN 1279 DoP, R\u003csub\u003ew\u003c\/sub\u003e test certificate from a UKAS-accredited acoustic lab (BS EN ISO 10140 methodology), BS EN 14449 laminated-glass certificate on the outer pane, and BS EN 12600 impact classification (Class 2(B)2 via the laminated outer — meets most Approved Document N critical-location requirements as a side benefit). For noise-mitigation grant applications, we supply the R\u003csub\u003ew\u003c\/sub\u003e + C\u003csub\u003etr\u003c\/sub\u003e + C figures as a complete documentation pack.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003ch3\u003eHow much quieter, in practice?\u003c\/h3\u003e\n\u003cp\u003eA 10-12 dB improvement is perceived as roughly halving loudness. If the room currently registers 50 dB(A) of background noise from outside (a typical urban room with 1990s DG facing a busy road), this upgrade typically drops that to 38-40 dB(A) — closer to a quiet residential street. The improvement is most noticeable for speech-intelligibility-band frequencies; low-frequency rumble drops less.\u003c\/p\u003e\n\n\u003ch3\u003eDoes it block low-frequency noise (lorries, basses)?\u003c\/h3\u003e\n\u003cp\u003ePartially. Low frequencies (below 250 Hz) are hard to block with glass mass alone — they're better attenuated with secondary glazing or mass-loaded walls. This unit drops low-frequency noise about 6-8 dB, vs 12-15 dB at mid frequencies. For dominant low-frequency sources (heavy goods routes, freight rail), R\u003csub\u003ew\u003c\/sub\u003e+C\u003csub\u003etr\u003c\/sub\u003e is the more honest figure (36-37 dB vs 40 dB R\u003csub\u003ew\u003c\/sub\u003e).\u003c\/p\u003e\n\n\u003ch3\u003eCan I get this as a triple-glazed unit?\u003c\/h3\u003e\n\u003cp\u003eYes — the \u003ca href=\"\/products\/triple-glazed-acoustic-unit-44db-rw\"\u003eTriple Glazed Acoustic Unit (44 dB Rw)\u003c\/a\u003e adds a third pane for a further 4 dB improvement, at additional cost and weight. For most projects, the double-glazed asymmetric flagship is the cost-optimal sweet spot.\u003c\/p\u003e\n\n\u003ch3\u003eWill my existing frame take this?\u003c\/h3\u003e\n\u003cp\u003eAt 28mm overall, this fits the same rebates as a standard 28mm DG — modern PVCu, aluminium, and timber frames designed for double glazing. The 23 kg\/m² weight is typically inside hinge ratings for windows up to 1500×1200. Confirm sash-balance ratings for very large units.\u003c\/p\u003e\n\n\u003ch3\u003eAcoustic PVB vs standard PVB — is the upgrade worth it?\u003c\/h3\u003e\n\u003cp\u003eYes, for acoustic-priority projects. Acoustic-grade PVB adds 3-5 dB across the 500-2500 Hz speech-intelligibility band over standard PVB at roughly £10-15\/m² premium. For a £200 unit, that's a 5-8% price increase for a 10-15% perceived noise reduction — typically the best £\/dB in the configurator.\u003c\/p\u003e\n\n\u003ch3\u003eSide-benefit: does this also count as safety glass?\u003c\/h3\u003e\n\u003cp\u003eYes. The laminated outer pane satisfies BS EN 12600 Class 2(B)2 — adequate for most critical locations under Approved Document N (door sidelights, low-level windows, bathroom glazing). For Class 1(C)1 (highest impact rating), specify toughened-plus-laminated in the configurator.\u003c\/p\u003e\n\n\u003ch3\u003eWarranty?\u003c\/h3\u003e\n\u003cp\u003e10 years on edge-seal integrity (BS EN 1279-2). 10 years on PVB delamination (BS EN 14449 standard). 10 years on argon retention to ≥80% of initial fill. R\u003csub\u003ew\u003c\/sub\u003e performance is warranted at the certified test value at installation date — frame-seal degradation over time is excluded from the glass warranty.\u003c\/p\u003e\n","brand":"Pane Relief","offers":[{"title":"600 × 400 mm","offer_id":61853203005770,"sku":"DG-AC40-600x400","price":45.0,"currency_code":"GBP","in_stock":true},{"title":"800 × 600 mm","offer_id":61853203038538,"sku":"DG-AC40-800x600","price":61.0,"currency_code":"GBP","in_stock":true},{"title":"1000 × 800 mm","offer_id":61853203071306,"sku":"DG-AC40-1000x800","price":102.0,"currency_code":"GBP","in_stock":true},{"title":"1200 × 1000 mm","offer_id":61853203104074,"sku":"DG-AC40-1200x1000","price":153.0,"currency_code":"GBP","in_stock":true},{"title":"1500 × 1200 mm","offer_id":61853203136842,"sku":"DG-AC40-1500x1200","price":229.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/3515\/2458\/files\/double-glazed-sealed-unit-igu-product-cutaway_779ff7fb-4383-47d1-b092-538c3ce8986a.webp?v=1779007259","url":"https:\/\/panerelief.co.uk\/products\/specialist-acoustic-laminated-glass-asymmetric-double-glazed-unit","provider":"Pane Relief","version":"1.0","type":"link"}