1837–1901
Secondary Glazing for Victorian Terrace
The classic South Yorkshire Victorian terrace is where secondary glazing earns its reputation — original box sashes stay in place while a slim vertical slider sits behind them. This page explains what we spec, why, and how the job runs from survey to install.
Local reference points
- Era
- 1837–1901
- Typical window
- vertical box sashes with single-glazed lights
- Top problem
- sash rattle, draughts and street noise
- Recommended service
- Soundproofing
- Recommended product
- vertical sliders
- Performance
- 45–54 dB reduction with a 100–150 mm cavity
Why victorian terrace owners choose secondary glazing
Original box sashes typically leak air around the meeting rail and the pulley wells — a room-side secondary sash seals both without touching the original.
A balanced vertical slider mirrors the original operation, so a bedroom window still feels like a sash from inside.
For terraces on main roads we spec 6.4 mm acoustic laminated glass with a 100 mm cavity as the default.
Recommended: Soundproofing
cut outside noise by up to 80%
45–54 dB reduction with a 100–150 mm cavity
The acoustic gain comes from air-gap decoupling — a 100 mm cavity between the existing pane and the secondary pane detunes the resonant frequencies that carry traffic noise into a room.
Recent installs nearby
Nether Edge Grade II sash retrofit
Six original box sashes fitted with balanced vertical secondary sliders — full listed-building consent secured in six weeks.
Moorgate HMO security retrofit
Ground-floor sashes across four HMO units fitted with key-lock hinged units to meet the licensing conditions.
Worksop Priory precinct terrace
Chronic bedroom mould eliminated with sealed lift-out panels behind original sashes.
Common questions
Will secondary glazing stop conversation-level noise from a neighbour?
Yes — mid-frequency speech is exactly what a laminated secondary pane damps hardest. We'd typically spec 6.8 mm on the secondary and keep the primary as-is.
Is there a warranty?
Yes — 10 years on the manufacture and installation, and a manufacturer's warranty on the glass units.
How much noise reduction can I realistically expect?
With a 100 mm cavity and 6.4 mm laminated secondary glass we routinely measure 40–47 dB Rw — enough to drop main-road traffic to a soft background hum.
Can I still open the original window?
Yes — every sliding, hinged and lift-out unit is designed to move clear so you can operate the primary window behind it.
Is it worth it on a modern double-glazed window?
For noise, yes — modern DG units were designed for thermal not acoustic performance, and a laminated secondary pane adds the acoustic mismatch they lack.
Prefer to talk it through?
Give us five minutes on the phone and we'll steer you to the right specification.
Next step for victorian terrace owners
Send us photos of one or two windows and we'll come back with a written quote and a spec sheet you can compare against replacement double glazing.