Holywood · County Down
Secondary Glazing in Holywood
Single-glazed sash windows in Holywood can stay as they are, with vertical sliding secondary glazing fitted inside to reduce draughts and cold.
- BT18
- Guide from £465
Internal secondary windows across Holywood
For noise reduction, the size of the air gap between the original window and the secondary unit matters a great deal, and a wider cavity generally performs better. Acoustic laminated glass and well-sealed frames improve results further, especially against traffic, rail and aircraft noise.
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.
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.
Glass for secondary glazing is heavy, so the frames need firm fixings into the reveal or a supporting sub-frame. The surveyor checks that plaster, timber linings and window boards are sound enough to carry the weight, and allows for any packing needed in uneven reveals.
What you get
- Removal of packaging and cleaning of new glass
- Survey of each window, reveal depth and sightlines
- Advice on opening style, glass and fire escape
- Fitting, sealing and checking every opening panel

Holywood at a glance
- Postcodes covered
- BT18 and the surrounding area, including Dundonald, Newtownabbey and Belfast
- Coast
- Holywood is about 2 km from the coast or a tidal estuary, so salt air and wind-driven rain are worth planning for. 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.
- Daylight and sun
- In Holywood the midwinter sun reaches about 12° above the horizon at noon, with roughly 7.0 hours of daylight, rising to about 59° and 17.0 hours in midsummer. Secondary glazing adds an extra layer of glass, which slightly reduces daylight. Low-iron or clear low-E glass keeps light loss to a minimum, while on sunny elevations solar control glass can help reduce overheating in rooms with large windows.
- Access and setting
- 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.
- Rules in Northern Ireland
- 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.
Guide prices in Holywood
| 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 |
Get a guide price for your size
Technical Booklet F1 sets the energy performance that replacement windows, doors and rooflights need to meet in Northern Ireland.
Choosing your secondary glazing
Vertical sliding
Panels slide up and down, with meeting rails aligned to sash windows so the secondary unit is discreet from inside and outside.
Horizontal sliding
Panels slide sideways, suiting wide casement windows and openings where you need regular access for cleaning or ventilation.
Fixed panel
A non-opening unit for windows never opened, giving the most airtight seal for noise and draught reduction.
Secondary Glazing in Holywood: questions
How much noise does secondary glazing block?
Results depend on the size of the gap between the windows, the glass type and thickness, the seals and the original window. A larger cavity and acoustic laminated glass give the strongest improvement. The survey checks reveal depth and noise sources, so the specification can be tailored to the noise you are dealing with.
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.
How much does secondary glazing cost?
The cost depends on the size and number of windows, the opening style, the type of glass, any arched or shaped heads, reveal depth and access. Acoustic and low-E glass cost more than standard clear glass, and shaped frames need more work. See the guide prices for typical windows, then get a written quote after the survey.
Can I still open my original windows?
Yes, as long as the secondary glazing has an opening panel in front of the part you need to open. Sliding and hinged panels give access to the original window for ventilation and cleaning. Lift-out and fixed panels suit windows you rarely or never open.
Do you cover Holywood for secondary glazing?
Yes. We can quote for secondary glazing across Holywood and the surrounding County Down area, including postcode districts BT18, and nearby Dundonald, Newtownabbey and Belfast. Start with your postcode on the quote form and a glazier will arrange a free survey before giving you a written quote.
Get a written quote in Holywood
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.