Treharris · Mid Glamorgan
uPVC Windows in Treharris
We cover Treharris and the rest of Mid Glamorgan for replacement uPVC windows, from a single bathroom window to a whole house, with survey, supply and fitting arranged.
- CF46
- Guide from £565
uPVC windows across Treharris
The price of uPVC windows depends mainly on size, the number of opening sashes, frame colour, glass specification and hardware. Bay windows, openings that need a tower or scaffold, and difficult removal of old frames add labour. See the guide prices for typical ranges; your written quote fixes the exact figure.
uPVC no longer means white only. Frames can be foiled in woodgrain or solid colours such as grey, black or cream, often outside only with white inside. Foils are bonded at the factory and should be cleaned with a soft cloth and mild detergent, because abrasive pads and solvents mark the surface.
Bay windows need extra care. Some older bays carry load from the wall or roof above, so the glazier checks the support before removal and may fit bay poles or ask for structural advice. Replacing a window in the same opening is different from widening it, which needs a new lintel.
uPVC window frames are made from extruded profiles with several internal chambers that trap air and slow heat loss. Larger frames, and those on exposed elevations, are usually reinforced with steel or aluminium inside the profile so they stay straight and the locks keep engaging properly over the years.
Included as standard
- Made-to-measure frames with sealed double glazed units
- Survey and measurement of every opening
- Removal and disposal of the old windows
- Fitting, packing and fixing into the existing opening

Local details for Treharris
- Postcodes covered
- CF46 and the surrounding area, including Nelson (Mid Glamorgan), Gelligaer and Mountain Ash
- Coast
- Treharris is well inland, around 23 km from the nearest coast, so salt exposure is not usually a factor.
- Daylight and sun
- In Treharris 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. uPVC frames are bulkier than aluminium, so they take a little more glass area from small windows. On south and west elevations, solar-control or neutral low-E glass limits overheating, while north-facing rooms benefit from high light-transmission glass and warm-edge spacers that reduce condensation.
- Access and setting
- Older rural cottages often have irregular openings, thick walls and timber lintels, so every frame is measured individually and the support above each opening is checked. Exposed hillside and open-field sites benefit from reinforced frames and careful sealing against driving rain.
- Rules in Wales
- In Wales, Approved Document N covers safety glazing: safety glass is needed in and around doors and in low-level glazing where people could walk into it.
Guide prices in Treharris
| Typical job | Guide price inc VAT |
|---|---|
| Casement window, 900 × 1050 mm | £565 – £725 |
| Casement window, 1200 × 1200 mm | £665 – £855 |
| Large window, 1800 × 1200 mm | £805 – £995 |
| Anthracite or woodgrain, 1200 × 1200 mm | £785 – £995 |
Get a guide price for your size
Wales sets its own energy standards in the Welsh Approved Document L. Replacement windows, doors and rooflights must meet the limiting values set there, which your quote will reference.
Specification choices
Georgian or astragal bars
Bars set between the panes or applied to the faces of the glass for a traditional divided-pane look.
Casement windows
Side-hung or top-hung sashes on friction hinges, suiting most houses, with easy-clean hinges that let upper-floor glass be cleaned from inside.
Woodgrain and colour foils
Grey, black, cream or woodgrain foils on one or both faces, so the frames can match a door or suit an older house.
uPVC Windows in Treharris: questions
Should I choose double or triple glazing?
Well-specified double glazing with low-E glass and warm-edge spacers can meet the energy standard for replacement windows, and the certified rating confirms it. Triple glazing adds a third pane, which helps on cold, noisy or north-facing elevations, but the units are heavier and need frames designed for them. We can quote both so you can compare.
Will fitting new windows damage my plaster or decor?
Some disturbance is normal, but it is usually limited to the edges of each opening. The glazier cuts out the old frame, fits the new one and finishes the inside with trims, sealant or filler. Older frames set deep into plaster may need some plaster repair, and we flag that at survey so it is covered in the quote.
What guarantee comes with new uPVC windows?
Manufacturer guarantees apply to new frames, sealed units and hardware, and the terms are confirmed in writing. Guarantee terms for the installation are set out in writing with your quote, so you know what is covered and for how long before you commit. Keep this paperwork with your building regulations certificate, because buyers' solicitors usually ask for both.
How much do uPVC windows cost?
The cost of uPVC windows depends on the size and number of windows, how many sashes open, the frame colour, the glass and the access. White casements with standard double glazing sit at the lower end, while foiled colours, triple glazing and bay windows cost more. See the guide prices for typical ranges; the written quote fixes the price for your specification.
Do you cover Treharris for uPVC windows?
Yes. We can quote for uPVC windows across Treharris and the surrounding Mid Glamorgan area, including postcode districts CF46, and nearby Nelson (Mid Glamorgan), Gelligaer and Mountain Ash. 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 Treharris
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.