Crawley · West Sussex
Secondary Glazing in Crawley
Single-glazed sash windows in Crawley can stay as they are, with vertical sliding secondary glazing fitted inside to reduce draughts and cold.
- RH10
- RH11
- Guide from £465
Acoustic secondary glazing in Crawley: what to know
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.
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.
Opening styles include vertical sliders that line up with sash window meeting rails, horizontal sliders for wide openings, hinged casements, lift-out panels for windows that are rarely opened, and fixed panes. The choice depends on how you use the window, cleaning access and fire escape needs.
Secondary glazing leaves the original window untouched and fits a second, independent window inside it. The air gap between the two works with the glass to reduce noise and heat loss. In most cases the installation can be taken out later without damaging the historic window or reveal.
What's included
- Written quote fixing the price for the specification
- Made-to-measure slim aluminium frames and glass
- Survey of each window, reveal depth and sightlines
- Removal of packaging and cleaning of new glass

Crawley at a glance
- Postcodes covered
- RH10, RH11 and the surrounding area, including Horley, Horsham and East Grinstead
- Coast
- Crawley is well inland, around 31 km from the nearest coast, so salt exposure is not usually a factor.
- Daylight and sun
- In Crawley the midwinter sun reaches about 15° above the horizon at noon, with roughly 7.7 hours of daylight, rising to about 62° and 16.3 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
- In city centres and busy streets, acoustic secondary glazing is a common response to traffic, rail and nightlife noise. Flats, listed buildings and conservation areas often limit external changes, which makes internal secondary glazing a practical option.
- Rules in England
- Approved Document K requires safety glass in critical locations in England: glazing in doors and in side panels within 300 mm of a door, up to 1500 mm above floor level, and any glazing in walls or partitions up to 800 mm above floor level.
Guide prices in Crawley
| 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
Listed buildings in England need listed building consent for most changes to historic windows or glass, and conservation areas can restrict changes visible from the street. Speak to the council's conservation officer before ordering.
What you can choose
Acoustic laminated glass
Laminated glass with a sound-dampening interlayer, combined with a generous cavity, for properties affected by traffic, rail or aircraft noise.
Lift-out panel
A lightweight panel that lifts out of its frame, for windows rarely opened, giving a slim and economical secondary unit.
Horizontal sliding
Panels slide sideways, suiting wide casement windows and openings where you need regular access for cleaning or ventilation.
Secondary Glazing in Crawley: questions
Does secondary glazing need safety glass?
It does in critical locations. In England, glass within 800mm of the floor, glass in doors and glass near doors are critical locations under Approved Document K, and these apply to secondary glazing too. Low-level secondary panes should be toughened or laminated safety glass. The surveyor checks each window during the survey.
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.
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.
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.
Do you cover Crawley for secondary glazing?
Yes. We can quote for secondary glazing across Crawley and the surrounding West Sussex area, including postcode districts RH10 and RH11, and nearby Horley, Horsham and East Grinstead. 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 Crawley
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.