Llantrisant · Mid Glamorgan
Secondary Glazing in Llantrisant
Secondary glazing in Llantrisant keeps your original windows in place while adding a slim inner window to cut noise, draughts and heat loss.
- CF72
- CF38
- Guide from £465
Secondary glazing across Llantrisant
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.
The price of secondary glazing depends on the size and number of windows, the opening style, the glass specification, any shaped or arched heads, reveal depth and condition, and access. Acoustic laminated glass and shaped frames cost more than standard clear glass in rectangular frames.
A low-emissivity coating on the secondary glass reflects heat back into the room and improves the insulation of the combined window. It is a useful choice for single-glazed sash and casement windows where the originals must be kept for character or planning reasons.
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.
Included as standard
- Advice on opening style, glass and fire escape
- Fitting, sealing and checking every opening panel
- Survey of each window, reveal depth and sightlines
- Made-to-measure slim aluminium frames and glass

Local details for Llantrisant
- Postcodes covered
- CF72, CF38 and the surrounding area, including Tonyrefail, Pontypridd and Pencoed
- Coast
- Llantrisant sits roughly 17 km from the nearest coastline, close enough that exposure on open or high ground is worth considering. Coastal properties often have older windows exposed to wind-driven rain and draughts. Secondary glazing adds a sealed inner layer that reduces draughts and cold, while the original window keeps out the weather and its condition is protected from inside.
- Daylight and sun
- In Llantrisant 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 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 Llantrisant
| 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
Where a window is an escape route, its replacement in Wales 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.
Low-E glass
Coated glass that reflects heat back into the room, improving insulation when the original window is single glazed.
Lift-out panel
A lightweight panel that lifts out of its frame, for windows rarely opened, giving a slim and economical secondary unit.
Secondary Glazing in Llantrisant: questions
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.
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.
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.
Which opening style should I choose?
Choose based on how you use the window. Vertical sliders suit sash windows and keep meeting rails aligned. Horizontal sliders suit wide windows. Hinged panels give full access for cleaning and escape. Lift-out and fixed panels suit windows that are rarely or never opened, and give the tightest seal for noise.
Do you cover Llantrisant for secondary glazing?
Yes. We can quote for secondary glazing across Llantrisant and the surrounding Mid Glamorgan area, including postcode districts CF72 and CF38, and nearby Tonyrefail, Pontypridd and Pencoed. 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 Llantrisant
Free survey for new glazing, clear guide prices and one point of contact for every glazing job.