Isleworth · Greater London
Secondary Glazing in Isleworth
Is traffic noise getting through the windows of your home in Isleworth? We can quote for acoustic secondary glazing tailored to each opening.
- TW7
- TW3
- TW5
- Guide from £465
About internal secondary windows in Isleworth
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.
Low-level secondary glazing is still glazing, so the safety glazing rules for critical locations apply. In England, Approved Document K treats glass within 800mm of the floor as a critical location, so low-level secondary panes should be toughened or laminated safety glass.
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.
Slim aluminium frames are designed to sit within the window reveal and line up with the original glazing bars or meeting rails. Matching sightlines keeps the secondary unit discreet from outside and inside, which matters for period homes and conservation areas.
What's included
- Made-to-measure slim aluminium frames and glass
- Removal of packaging and cleaning of new glass
- Fitting, sealing and checking every opening panel
- Survey of each window, reveal depth and sightlines

Local details for Isleworth
- Postcodes covered
- TW7, TW3, TW5 and the surrounding area, including Hounslow, Heston and Richmond
- Coast
- Isleworth is well inland, around 49 km from the nearest coast, so salt exposure is not usually a factor.
- Daylight and sun
- In Isleworth the midwinter sun reaches about 15° above the horizon at noon, with roughly 7.6 hours of daylight, rising to about 62° and 16.4 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 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 Isleworth
| 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.
Choosing your secondary glazing
Low-E glass
Coated glass that reflects heat back into the room, improving insulation when the original window is single glazed.
Horizontal sliding
Panels slide sideways, suiting wide casement windows and openings where you need regular access for cleaning or ventilation.
Acoustic laminated glass
Laminated glass with a sound-dampening interlayer, combined with a generous cavity, for properties affected by traffic, rail or aircraft noise.
Secondary Glazing in Isleworth: 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.
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.
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 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.
Do you cover Isleworth for secondary glazing?
Yes. We can quote for secondary glazing across Isleworth and the surrounding Greater London area, including postcode districts TW7, TW3 and TW5, and nearby Hounslow, Heston and Richmond. 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 Isleworth
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.