Northallerton · North Yorkshire
Secondary Glazing in Northallerton
Single-glazed sash windows in Northallerton can stay as they are, with vertical sliding secondary glazing fitted inside to reduce draughts and cold.
- DL7
- DL6
- Guide from £465
Secondary glazing for sash windows for homes and businesses in Northallerton
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.
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.
Owners of listed buildings should seek listed building consent before installing secondary glazing, as the requirements depend on the building and the council. Secondary glazing is often seen as a minimal, reversible change, but carrying out works that need consent without it is a criminal offence.
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.
What a typical job includes
- Written quote fixing the price for the specification
- Survey of each window, reveal depth and sightlines
- Fitting, sealing and checking every opening panel
- Removal of packaging and cleaning of new glass

Northallerton at a glance
- Postcodes covered
- DL7, DL6 and the surrounding area, including Darlington, Ripon and Thornaby-on-Tees
- Coast
- Northallerton is well inland, around 35 km from the nearest coast, so salt exposure is not usually a factor.
- Daylight and sun
- In Northallerton 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 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 Northallerton
| 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
Approved Document B covers escape windows. Where an existing window is an escape route, typically in first-floor bedrooms, its replacement should give at least the same escape opening as before.
Choosing your secondary glazing
Fixed panel
A non-opening unit for windows never opened, giving the most airtight seal for noise and draught reduction.
Hinged casement
Panels open inwards like a door, giving full access to the original window, and can be chosen for escape windows.
Horizontal sliding
Panels slide sideways, suiting wide casement windows and openings where you need regular access for cleaning or ventilation.
Secondary Glazing in Northallerton: questions
How do I clean and look after secondary glazing?
Open or remove the panels as designed, then clean the glass with mild soapy water and a soft cloth. Wipe the aluminium frames and runners, and keep tracks free of dust so panels slide smoothly. Check seals and catches occasionally. Avoid abrasive cleaners, which can scratch coated glass.
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.
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.
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.
Do you cover Northallerton for secondary glazing?
Yes. We can quote for secondary glazing across Northallerton and the surrounding North Yorkshire area, including postcode districts DL7 and DL6, and nearby Darlington, Ripon and Thornaby-on-Tees. 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 Northallerton
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.