Glazing & Secondary Glazing Panels

Transparent panels for glazing projects, selected against the required grade, impact test, frame and installation details.

Plastic glazing is often chosen for lower weight and reduced sharp-fragment risk compared with glass; the result depends on material grade, thickness, frame and installation. Which of the two materials you choose depends on whether the panel is more likely to be hit or scratched.

We supply glazing installers, window fabricators and distributors — cut to your survey schedule rather than as stock sheet you break down again.

Which material for which glazing job

Application	Specify	Reason
Secondary glazing, internal	Clear acrylic	Best clarity, harder surface, lower cost; no impact risk indoors
Safety and anti-vandal glazing	Clear polycarbonate	Select grade and assembled glazing against the specified impact or security test
School, sports hall, custodial	Polycarbonate	Impact and deliberate damage are expected, not exceptional
Listed and heritage buildings	Acrylic	Optical quality closest to old glass; slim frames possible
Roof glazing and rooflights	Multiwall polycarbonate	Insulation and span — see roofing
Machine and equipment windows	Polycarbonate	See machine guarding

Secondary glazing in practice

Secondary glazing is the highest-volume use of clear acrylic in the glazing trade, and it is almost always the right material: the panel sits inside, out of the weather, and nothing is going to hit it. Typical specification is 3–4 mm clear acrylic in a magnetic or hinged frame.

Two practical points worth building into your quotes:

Allow for movement. Acrylic expands roughly 3–4 mm per metre across a normal temperature range. A panel cut hard against the frame will bow in summer. Leave a clearance gap; do not cut to exact aperture.

Get the survey right first. Old window apertures are rarely square. Panels cut to a nominal rectangle need trimming on site, which defeats the purpose of factory cutting. Send actual surveyed dimensions and we cut to them.

Thickness and glazing method

Panel size	Acrylic	Polycarbonate
Up to 0.5 m²	3 mm	2–3 mm
0.5–1.5 m²	4–5 mm	3–4 mm
1.5–3 m²	6–8 mm	4–6 mm
Above 3 m²	8–10 mm	6–10 mm

Glaze into a gasket or a dry-glazed bead wherever possible. If a sealant is unavoidable, use a neutral-cure silicone — acetoxy (vinegar-smelling) silicones attack polycarbonate and cause crazing that appears weeks later, long after the installer has left.

Typical applications

Secondary glazing panels for period and listed buildings
Safety glazing in schools, sports halls and public buildings
Replacement glazing for windows and doors
Balustrade and stair infill panels
Greenhouse, shed and outbuilding glazing

Minimum order and lead time

For polycarbonate glazing sheet projects, SinoPlastix checks safety glazing selection before confirming the material. Send the span or finished dimensions, exposure and load conditions, preferred appearance, fabrication needs, and quantity. Standard stock sizes and colours normally run in 7–10 days; non-standard extrusion in 12–18 days; allow another 3–7 days for CNC work. The published starting point is 100 m² or 1 tonne, quoted in USD on FOB, CIF or DDP terms. See MOQ, lead time and shipping for planning details.

Questions buyers ask

Acrylic or polycarbonate for secondary glazing?

Acrylic in nearly every case. It is clearer, harder-wearing and cheaper, and an internal secondary panel faces no impact risk. Choose polycarbonate only where deliberate damage or ball impact is realistic.

Will plastic glazing scratch when cleaned?

Acrylic is noticeably harder than uncoated polycarbonate and stands up to normal cleaning. For polycarbonate in a cleaned position, specify the hard-coated grade. Never use ammonia-based glass cleaner on either.

Can you cut panels to my surveyed sizes?

Yes — that is the point of ordering from us rather than buying stock sheet. Send the schedule as a spreadsheet or DXF and we cut at the order-specific CNC tolerance confirmed after material, thickness, part geometry and drawing review, with a clearance allowance if you specify one.

Does plastic secondary glazing improve insulation?

Yes — the benefit comes mainly from the trapped air gap between the existing window and the new panel, so the frame detail and seal matter as much as the panel material.

Request a quote MOQ & shipping

Define the safety-glazing risk before choosing thickness

“Safety glazing” can describe accidental human impact, machine fragments, vandalism, a protective screen or secondary glazing. These are different load cases. Provide the opening size, support on each edge, likely impact source, indoor or outdoor exposure and any standard or test method named by the project.

Input	Why it matters
Impact object, mass and velocity	Separates general guarding from a defined impact requirement
Frame and supported opening	The sheet and support system act together
Coolants, cleaners and outdoor exposure	Identifies chemical, UV and surface-protection needs
Required report or standard	Determines whether available evidence applies to the ordered grade and thickness

Evidence and fabrication boundary

Do not infer a security, ballistic or code rating from the material name alone. Ask for evidence tied to the relevant grade, thickness, specimen and test scope. Holes, cut-outs, countersinks and edge distances must be reviewed from the finished drawing because fabrication can change local stress around the fixing.

For machine-specific guarding, continue to machine guarding polycarbonate. For drawing review, use the safety-glazing RFQ route.

From the factory