County Londonderry · Northern Ireland

Secondary Glazing in County Londonderry

Secondary glazing in County Londonderry keeps your original windows in place while adding a slim inner window to cut noise, draughts and heat loss.

Guide from £465
5 towns covered
Postcode areas BT

Secondary glazing listed buildings for homes and businesses in County Londonderry

If an existing window is relied on for escape in a fire, the secondary glazing in front of it must open easily and give enough clear opening. The surveyor checks which windows are escape windows, so the opening style and catches do not block a way out.

Condensation in the gap between the two windows is reduced by making the secondary unit the more airtight of the two. The original window should not be fully sealed, so any moisture that gets into the cavity can escape outside rather than being trapped against the glass.

The price of secondary glazing depends on the size and number of windows, the opening style, the glass specification, any shaped or arched heads, reveal depth and condition, and access. Acoustic laminated glass and shaped frames cost more than standard clear glass in rectangular frames.

Secondary glazing can also add security, because an intruder would have to break through two separate windows. Laminated glass and locking catches on the secondary unit add further resistance, which is useful for ground-floor and basement windows in period properties.

Sash window with secondary glazing in a period sitting room

Towns we cover for secondary glazing in County Londonderry

Choose your town for local details, nearby areas and the postcode districts we cover.

What applies in County Londonderry

Technical Booklet V covers safety glazing in Northern Ireland, including glass in and around doors and low-level glazing where people could walk into it.

Where a window provides an escape route, its replacement in Northern Ireland should give at least the same escape opening as before.

County Londonderry has its own coastline, so for homes and businesses near the sea, salt air and wind-driven rain are part of the brief. Coastal properties often have older windows exposed to wind-driven rain and draughts. Secondary glazing adds a sealed inner layer that reduces draughts and cold, while the original window keeps out the weather and its condition is protected from inside.

Rural cottages and period homes often have single-glazed timber windows that cannot easily be replaced. Secondary glazing reduces draughts and heat loss in exposed locations, and the surveyor allows for uneven reveals and older plaster when fixing frames.

Guide prices

Guide prices inc VAT for typical jobs. Remote and island locations are quoted by arrangement. Your written quote fixes the price after measuring.
Typical job	Guide price inc VAT
Slider, 900 × 1200 mm	£465 – £595
Slider, 1200 × 1600 mm	£665 – £845
Acoustic glass, 1000 × 1400 mm	£675 – £865

Choosing your secondary glazing

Lift-out panel

A lightweight panel that lifts out of its frame, for windows rarely opened, giving a slim and economical secondary unit.

Low-E glass

Coated glass that reflects heat back into the room, improving insulation when the original window is single glazed.

Hinged casement

Panels open inwards like a door, giving full access to the original window, and can be chosen for escape windows.

Vertical sliding

Panels slide up and down, with meeting rails aligned to sash windows so the secondary unit is discreet from inside and outside.

Secondary Glazing in County Londonderry: questions

Will secondary glazing cause condensation?

It can, if the original window is sealed tighter than the secondary unit, because warm, moist room air then gets trapped in the cavity. The secondary unit should be the more airtight of the two, and the original window should not be fully sealed. Opening the secondary panel lets room air into the cavity, so close it again afterwards.

Is secondary glazing as good as double glazing?

It depends on the goal. For noise, secondary glazing is often more effective, because the wider gap between the two windows reduces sound better than the narrow cavity of a sealed unit. For heat, a well-sealed secondary unit with low-E glass significantly improves a single-glazed window. It also keeps original windows, which matters in listed buildings.

Do I need permission for secondary glazing on a listed building?

You should seek listed building consent from the council's planning department before installing secondary glazing on a listed building. Secondary glazing is often seen as a reversible, low-impact change, but consent requirements depend on the building. Carrying out works that need consent without it is a criminal offence. If your home is not listed but is in a conservation area, check with the council if you are unsure.

Which opening style should I choose?

Choose based on how you use the window. Vertical sliders suit sash windows and keep meeting rails aligned. Horizontal sliders suit wide windows. Hinged panels give full access for cleaning and escape. Lift-out and fixed panels suit windows that are rarely or never opened, and give the tightest seal for noise.

Which parts of County Londonderry do you cover for secondary glazing?

We cover the whole of County Londonderry, including Derry/Londonderry, Coleraine, Limavady, Magherafelt and Portstewart, and postcode areas BT. Building rules for secondary glazing here follow the regulations for Northern Ireland. Enter your postcode on the quote form and we will confirm cover; then a glazier will arrange a free survey before giving you a written quote.

Other glazing services in County Londonderry

All glazing in County Londonderry · Secondary Glazing across the UK

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