Laminated glass for residential builds: PVB and SGP interlayers, AS 1288 selection

TL;DR

Laminated glass is two or more panes of annealed (or toughened) glass bonded with a plastic interlayer, typically polyvinyl butyral (PVB) at 0.38 mm to 1.52 mm thick. Under impact, the glass cracks but the interlayer retains the fragments in place, so the pane stays in the opening rather than falling out. That makes it a Grade A safety glass under AS/NZS 2208:1996 and the second safety-glass option (alongside toughened glass) accepted by AS 1288:2021. Laminated wins over toughened where the post-break behaviour matters: balustrades (the pane stays in place after impact rather than fragmenting away and exposing a fall hazard), overhead glazing (skylights, roof glazing where falling fragments would be a hazard), security glazing (impact resistance and retention), acoustic glazing (the PVB interlayer dampens sound transmission), and bushfire-prone properties at BAL-29+ (where retention under flame impact matters). Premium SGP interlayer (SentryGlas Plus, ionoplast) replaces PVB for higher stiffness and longer-term residual strength after the glass breaks, used in frameless cantilevered balustrades and structural glass elements. PVB also blocks 99%+ of UV light, an unintended bonus for sun-facing glazing. The two specification calls: interlayer type (PVB volume / SGP premium) and thickness build-up (e.g. “6.38 mm” = 3 mm + 0.38 PVB + 3 mm; “8.76 mm” = 4 mm + 0.76 PVB + 4 mm; “13.52 mm” = 6 mm + 1.52 PVB + 6 mm). The job-killer is water exposure to the laminated edge over time: water wicking into the PVB causes edge delamination (white milkiness creeping in from the edge); poor edge sealing in wet locations leads to early replacement.

What it is

Laminated glass is manufactured by sandwiching one or more interlayer films between two or more panes of glass, then bonding the assembly under heat and pressure in an autoclave. The glass panes can be annealed (the volume default) or toughened (premium, for higher impact and post-break strength) or even heat-strengthened (intermediate option).

The interlayer does the safety work:

Interlayer	Properties	Where used
PVB (polyvinyl butyral)	Standard interlayer; thicknesses 0.38, 0.76, 1.14, 1.52 mm; UV-blocking; sound-dampening	Volume residential and commercial
SGP (SentryGlas Plus / ionoplast)	Premium; ~5× stiffer than PVB; better edge stability in wet conditions; better residual strength	Frameless cantilevered balustrades, structural glass
EVA (ethylene-vinyl acetate)	Lower-cost; less common in residential laminated	Specialist applications
Acoustic PVB (e.g. Saflex Q)	PVB tuned for higher sound dampening	Acoustic-critical residential (music, theatre, near road or rail)
Decorative interlayers (coloured, textured, fabric-encased)	Decorative effect alongside safety	Architectural feature glazing

Glass + PVB nomenclature: a “6.38” laminated panel is 3 mm glass + 0.38 mm PVB + 3 mm glass. A “8.76” is 4 + 0.76 + 4. A “13.52” is 6 + 1.52 + 6. The interlayer thickness drives the safety performance: thicker PVB tolerates larger impacts before breaking through.

Grade A safety glass

Like toughened glass, laminated glass that meets AS/NZS 2208:1996 impact tests is classified Grade A safety glass. The break pattern is fundamentally different from toughened:

Glass type	Break pattern
Toughened	Whole pane shatters into small cubic fragments
Laminated	Glass cracks (radial / shatter pattern) but fragments stay bonded to the interlayer; pane retains its position in the frame

Both are AS 1288-acceptable safety glass; the post-break behaviour is the selection driver.

AS 1288 applications: laminated vs toughened

Both laminated and toughened meet the AS 1288 safety glass requirement, but the post-break retention of laminated makes it preferred in specific applications:

Application	Toughened	Laminated	Why laminated wins
Shower screens	Volume choice	Acceptable	Toughened cheaper, fragmentation not a hazard in shower
Internal doors	Volume choice	Acceptable	Cost
Balustrades (any height)	Acceptable in framed balustrades	Preferred for frameless and structural	Post-break retention prevents fall hazard
Skylights / overhead glazing	Limited	Required	Falling fragments below glazing is unacceptable
Pool fencing	Acceptable	Acceptable	Either works
Security glazing	Limited	Required	Impact retention; deter forced entry
Acoustic glazing	Limited acoustic benefit	Preferred	PVB dampens sound transmission
Bushfire BAL-29+	Acceptable with frame system	Often preferred	Retention under flame and impact
Doors / side panels above 800 mm sill	Acceptable	Acceptable	Either

For frameless balustrades in particular: the NCC requires that a balustrade pane stays in place after impact. Toughened glass that fragments completely under impact leaves an open void to the drop below: a fall hazard. Laminated balustrade glass cracks but stays in the frame, preserving the fall protection. SGP interlayer is the premium choice for the highest-spec frameless balustrades.

Thickness build-ups

Build-up	Total nominal thickness	Typical residential application
3 + 0.38 + 3 (6.38 mm)	~6.4 mm	Standard residential safety glazing; door panels
4 + 0.38 + 4 (8.38 mm)	~8.4 mm	Larger doors, side panels
4 + 0.76 + 4 (8.76 mm)	~8.8 mm	Acoustic, security; thicker PVB increases retention
5 + 0.76 + 5 (10.76 mm)	~10.8 mm	Skylights, premium glazing
6 + 1.52 + 6 (13.52 mm)	~13.5 mm	Frameless balustrades, heavy-duty applications
8 + 1.52 + 8 (17.52 mm)	~17.5 mm	Premium balustrades, structural glass
Toughened laminated (toughened panes with PVB)	Same nomenclature with “T” suffix	Maximum performance: post-break retention + 4-6× strength

For frameless balustrades, the specifier typically reads AS 1288 selection table to confirm thickness against pane size and loading; structural design under AS 1288 Section 7 may apply.

UV blocking and acoustic benefits

PVB interlayer blocks approximately 99%+ of UV-A and UV-B radiation that hits the glass surface. This is an unintended-but-useful property:

Furniture and artwork: laminated glazing in living and bedroom windows materially reduces UV fade of carpet, fabric, and artwork
Skin protection: UV through glazing causes some skin damage; laminated reduces it
Plant growth: some plant species near west-facing windows benefit from filtered UV

The acoustic benefit comes from the damping effect of the PVB interlayer. Compared to monolithic glass of the same thickness, laminated glass typically gives a 1 to 5 dB improvement in Rw (sound reduction). For acoustic-critical applications (near road, rail, or in music spaces), the dedicated acoustic PVB (Saflex Q, Kuraray Trosifol SC+) delivers 5 to 10 dB improvement over standard PVB.

Bushfire (BAL) applications

Under AS 3959:2018, laminated glass is increasingly the preferred option for higher BAL ratings:

BAL rating	Glazing system
BAL-12.5	Single glazed toughened (4 mm minimum) OR laminated; verify product BAL rating
BAL-19	Toughened 5 mm OR laminated 6.38; AS 3959-compliant frames
BAL-29	Toughened 6 mm OR laminated 6.38; bushfire shutters for some openings
BAL-40	Laminated (typically 5+ mm with 0.76 PVB minimum); bushfire shutters required
BAL-FZ	Specialist fire-rated wired or laminated systems

Laminated retains the assembly after the initial impact / thermal shock, giving the building envelope better post-event integrity than toughened that fully fragments.

Australian manufacturers and brand interlayers

Laminated glass is processed by glass merchants from float-glass substrate plus interlayer supplied by specialist film makers:

Interlayer brand	Type	Where used
Saflex (Eastman)	PVB; Saflex Q for acoustic	Volume residential
Trosifol (Kuraray)	PVB; Trosifol SC+ acoustic	Volume; specifier-led
SentryGlas Plus (Trosifol / Kuraray)	SGP ionoplast	Premium structural, frameless balustrades
EVASAFE (Bridgestone)	EVA	Specialist Asian-supplied product

The volume Australian glass processors (Viridian, G.James, IGA, Sydney Glass Centre) all produce laminated glass to AS 1288 from float-glass stock using these interlayers.

Common defects and on-site issues

Edge delamination (milky white edge creeping in): water absorbed into PVB at exposed edges. Caused by inadequate edge sealing in wet locations (shower screens, pool surrounds, exterior balustrades). Specify SGP interlayer or sealed edge frame for wet exposure.
Bubble formation in interlayer: rare manufacturing defect; the autoclave process should eliminate bubbles. Visible after cure.
Wrong build-up specified: 6.38 ordered where 8.76 is required for size. Re-order required; cannot be modified post-lamination.
Toughened-laminated edge chipping: when toughened panes are laminated, edge chips on the toughened component can lead to whole-pane shattering. Source from high-quality processors with edge work pre-toughening.
PVB exposed to direct heat (radiator, heat lamp): PVB can soften at elevated temperatures (~60-80°C). Maintain clearance from heat sources.
Glazing without setting blocks: same rule as toughened and float. Setting blocks at base of pane distribute load.
Failure to specify safety glass mark: AS/NZS 2208 stamp must be on each pane. Unmarked laminated cannot be used as safety glazing.

Pricing (2026 indicative, ex-GST, supply only)

Build-up	Per square metre (supply)
6.38 standard PVB (basic balustrade or door)	$130-200
8.76 standard PVB	$180-280
10.76 standard PVB	$230-340
13.52 standard PVB (frameless balustrade)	$300-440
Acoustic PVB (Saflex Q) premium	+20-40% over standard PVB
SGP interlayer (SentryGlas Plus) premium	+40-80% over standard PVB
Toughened-laminated (toughened panes) premium	+60-100% over standard laminated

For a typical residential frameless balustrade (5 m perimeter, 1.1 m high, 13.52 PVB laminated), supply cost is approximately $1,800 to $2,800; installed cost adds glazier labour plus fixing hardware (around $1,500 to $3,000 for the install).

Standards and references

Standards Australia, AS 1288:2021 Glass in buildings: selection and installation. https://store.standards.org.au (verified 2026-05-13).
Standards Australia, AS/NZS 2208:1996 Safety glazing materials in buildings. https://store.standards.org.au (verified 2026-05-13).
Standards Australia, AS 3959:2018 Construction of buildings in bushfire-prone areas. https://store.standards.org.au/product/as-3959-2018 (verified 2026-05-13).
Australian Building Codes Board, NCC 2022 Volume Two Part H4 (Safe movement and access). https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two (verified 2026-05-13).