Castlereagh · County Down
Sash Windows in Castlereagh
Homeowners and landlords in Castlereagh can get a written sash window quote that fixes the price for the joinery, glass, colour and hardware shown.
- BT6
- BT5
- BT7
- Guide from £1,495
Double glazed sash windows in Castlereagh: what to know
Sash window prices depend on size, timber or uPVC, whether you replace the whole frame or just the sashes, the glazing bar pattern, horns and mouldings, glass type and the paint colour. Listed or conservation work that needs matching details costs more. See the guide prices for typical ranges.
Security on sash windows comes from keyed sash locks at the meeting rails, sash stops that limit the opening for ventilation and child safety, laminated glass, and close-fitting staff and parting beads. Ground-floor sashes in older houses are often the weakest point, so locks are worth upgrading during replacement.
Heavy double glazed sashes need matching weights. When single glazed sashes are swapped for double glazed ones in an existing box, the old weights are usually too light, so the glazier re-weighs each sash to stop it dropping or creeping up, and checks the pulleys can carry the load.
Sash windows can be supplied as complete new frames, or as new double glazed sashes fitted into an existing sound box frame. Keeping the box retains original linings and architraves and reduces disturbance to plaster, but only works when the frame is free of rot and still square.
Included as standard
- Weights or balances set for smooth, even sliding
- Double glazed units, with safety glass where required
- Made-to-measure timber or uPVC sash windows
- Sealing, finishing and written guarantee terms

Local details for Castlereagh
- Postcodes covered
- BT6, BT5, BT7 and the surrounding area, including Belfast, Dundonald and Carryduff
- Coast
- Castlereagh is about 5 km from the coast or a tidal estuary, so salt air and wind-driven rain are worth planning for. Salt-laden wind and driving rain shorten the life of paint on exposed sashes, so coastal timber windows benefit from durable timbers, good factory coatings and regular inspection. Brass or stainless sash furniture resists corrosion better than plated steel near the sea.
- Daylight and sun
- In Castlereagh 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. Glazing bars and deep frames reduce daylight, so slimmer bars and high light-transmission low-E glass help north-facing rooms. Tall south-facing sashes can let in strong summer sun; the top sash can be lowered to vent warm air out at high level.
- Access and setting
- Older rural houses often have sash openings that are out of square, with soft stone or lime plaster around them, so each window is measured individually and fitted gently. Exposed sites benefit from draught seals and robust weatherboards on the bottom sash.
- 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 Castlereagh
| Typical job | Guide price inc VAT |
|---|---|
| uPVC sliding sash, 900 × 1500 mm | £1,495 – £1,995 |
| Timber-effect uPVC sash, 900 × 1500 mm | £1,795 – £2,295 |
| Painted timber sash, 900 × 1500 mm | £2,595 – £3,295 |
Get a guide price for your size
Replacement windows on houses in Northern Ireland are often permitted development, but conservation areas and listed buildings can need consent. Check with the council's planning office.
Specification choices
Tilt-in sashes
Sashes that tilt inwards for cleaning upper-floor glass from inside, and can help provide an escape opening.
Replacement sashes only
New double glazed sashes fitted into your existing sound box frame, keeping original linings, architraves and plasterwork.
Timber box sash
Traditional weights, cords and pulleys in a box frame, made in engineered softwood or hardwood and factory painted to your colour.
Sash Windows in Castlereagh: questions
Can I have double glazed sash windows in a listed building?
Sometimes, but listed building consent is needed for significant works, and some councils will only accept repair of the original windows or slim double glazing with matching details. Secondary glazing is often accepted where new windows are not. Speak to your council's conservation officer before ordering; we can provide drawings and specifications to support an application.
What maintenance do timber sash windows need?
Timber sash windows need periodic repainting, how often depends on exposure, orientation and colour, plus routine checks of cords, pulleys and seals. Keep paint off the running surfaces, clean the sills and touch up chips before water gets in. Factory-finished timber lasts longer between coats than site-painted joinery, but still benefits from yearly inspection.
How much do sash windows cost?
The cost of sash windows depends on size, material, whether you replace the whole frame or only the sashes, the glazing bar pattern, the glass and the finishing details such as horns and mouldings. Timber usually costs more than uPVC, and listed building work costs more again. See the guide prices for typical ranges; the written quote fixes your price.
Will double glazed sashes be too heavy for my existing frame?
Double glazed sashes are heavier than single glazed ones, so the box frame, pulleys and weights must cope. When new sashes go into an existing box, the glazier checks the pulleys and adds or replaces weights so each sash balances. If the box is weak or rotten, a new frame is the better option, and the survey will tell you.
Do you cover Castlereagh for sash windows?
Yes. We can quote for sash windows across Castlereagh and the surrounding County Down area, including postcode districts BT6, BT5 and BT7, and nearby Belfast, Dundonald and Carryduff. 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 Castlereagh
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.