The 4 Opening Styles of Secondary Glazing — Which One Belongs on Your Window?

Almost every enquiry we take in London starts with the same two questions: how much noise will secondary glazing stop, and what will it look like on my window? The second question is really a question about opening style — how the internal panel moves when you want to reach the primary window behind it.

There are four opening styles in common use across London period homes: sliding, hinged, lift-out and fixed. They share the same acoustic physics — mass, air gap and airtight seals — but they differ sharply in access, ventilation and cost. Choosing the wrong one is the most common reason a technically correct installation feels wrong to live with.

1. How opening style affects acoustic performance

Noise reduction is driven by three variables: the mass of the glass (6.8mm to 12.8mm acoustic laminate), the depth of the cavity between the primary and secondary pane (100–200mm), and the integrity of the perimeter seal. Opening style only affects the third — but the third matters more than most buyers expect.

Opening style	Typical seal	Realistic dB reduction	Indicative price per window
Sliding (horizontal or vertical)	Brush + wiper seals on the track	42–51dB	From £480
Hinged (side-hung)	Twin-compression EPDM on all four edges	45–52dB	From £520
Lift-out	Continuous compression EPDM, no track breaks	Up to 54dB	From £420
Fixed	Fully bedded perimeter seal	Up to 54dB	From £400

Sliders lose a small amount of performance because a track cannot compress a seal the way a closing leaf can. In practice the gap between a well-made slider and a lift-out panel is 2–4dB on the same glass — audible, but rarely decisive if you actually need to open the window every day.

2. Sliding secondary glazing — the everyday default

Horizontal sliders suit casements and wide openings; vertical sliders mirror the movement of a box sash and are the natural fit for most London sash windows. Panels move within a slim aluminium track, so nothing projects into the room and curtains, shutters and blinds stay usable.

Choose sliding when the window is opened regularly for ventilation, when the reveal is shallow, or when the room has furniture close to the wall. Full specifications, sizes and prices are on the sliding secondary glazing page.

3. Hinged secondary glazing — full access to the primary window

Hinged units swing clear of the reveal on side hinges, exposing the entire primary window. That matters where the original window has working shutters, security locks, or historic glass that needs periodic maintenance, and on any window you clean from the inside.

Because a hinged leaf compresses an EPDM seal on all four edges when latched, it typically outperforms a slider by 1–3dB. Costs, the survey process and installation detail are covered on the hinged secondary glazing page.

4. Lift-out secondary glazing — maximum discretion

A lift-out panel has no track and no visible hardware. It is lifted into a compression channel and removed by hand for cleaning or seasonal ventilation. With no track breaks in the seal line, it achieves the highest measured reductions of the operable styles — up to 54dB with 10.8mm acoustic laminate.

It is the right choice for stairwell and landing windows, light wells, dormers, and the side flanks of Victorian bays. See the lift-out secondary glazing page, and our longer lift-out case study guide.

5. Fixed secondary glazing — the sealed option

Fixed panels are permanently bedded into the reveal. They deliver the best acoustic and thermal result per pound, but the primary window can only be reached by removing the unit. We specify fixed panels only where a window is genuinely never opened and where building regulations do not require the opening as a means of escape.

6. Choosing by room and window type

• Street-facing bedroom sash: vertical slider, 10.8mm laminate, 150mm gap — see quiet bedrooms.
• Nursery: hinged or lift-out with laminate glass for safety — see nurseries.
• Home office on a bus route: slider or hinged with 12.8mm laminate — see home offices and traffic noise.
• Victorian bay: sliders across the front facets, lift-out on the side returns — see bay windows.
• Listed building or conservation area: lift-out or hinged, reversible fixings only — see listed buildings and conservation areas.
• Stairwell or light well: lift-out or fixed.

7. What our survey decides for you

On a London survey we measure the external and internal dB profile, the reveal depth available for the air gap, and how you actually use each window. The output is a window-by-window schedule: opening style, glass specification and target dB. Most houses end up with a mix — sliders in the principal rooms, lift-out panels on stairwells and bay returns.

You can model costs first with our ROI calculator, review fixed prices on the pricing page, or request a free bespoke survey.