Glass-only replacement · South Glamorgan
Triple glazed sealed unit replacement in Cardiff
From the first measure to the handover pack, we handle triple glazed replacement sealed units for homes in Cardiff and the rest of South Glamorgan.

Triple units for frames that can take them; better double units when they cannot. Sealed unit replacement means changing only the glass in an existing frame.
Winter light and glass choice in Cardiff
In Cardiff, midday sun in late December sits around 15° high, with roughly 7 h 50 min of daylight. For windows facing north or shaded by neighbours, cutting heat loss matters more than solar gain; on open south-facing glass, ask about a higher solar-gain unit.
Guide prices in Cardiff
| Guide | Supply and fit, inc VAT |
|---|---|
| Small unit up to about 0.6 m2, frame checked first | £145 – £195 |
| Medium unit about 0.6 to 1.2 m2 | £195 – £245 |
| Large unit about 1.2 to 2 m2 | £295 – £395 |
Guide prices. Your written quote after the free survey fixes the price for the specification shown.
Rules for glass-only replacement in Wales
The rules for replacement windows in Wales are set by Approved Document L for Wales (2022 edition, with 2024 amendments): 1.4 W/m²K, or a Window Energy Rating of band B or better. As in England, replacement windows are a controlled fitting: a competent person scheme installer self-certifies the work, or building control approves it.
Before ordering: Householder permitted development rules do not cover flats, and councils can remove rights with Article 4 directions. Listed buildings need listed building consent. Check with your council before changing the style or material.
How it works
We start with a survey, not a sales pitch: measurements, the structure above any bays, trickle-vent needs and escape windows. The quote that follows fixes the price, and anything unexpected on the day is agreed with you first.
- Free survey and a written quote fixed for the specification
- Glass build-up and whole-window U-value on every quote
- Written handover pack at the end of the job
- Guarantees on frames, units and fitting in writing
Questions from Cardiff
Why are my windows misting between the panes?
The seal around the unit has failed and moist air has got in. Only replacing the unit fixes it.
Can I put triple glazing in my existing windows?
Usually not in a way that helps. Most frames take up to about 28 mm units; a triple unit that thin performs about the same as, or worse than, good double glazing. We check your frames before recommending anything.
How long does it take to get triple glazed replacement sealed units fitted in Cardiff?
After the survey, typical manufacture time is 1 to 2 weeks for units, and replacing the units usually takes a few hours to a day.
Do I need permission for triple glazed replacement sealed units in Cardiff?
In Wales, householder rules do not cover flats, councils can use Article 4 directions, and listed buildings need consent. Check whether your street is in a conservation area or covered by an Article 4 direction before changing the style.
Nearby
Nearby towns on our list include Penarth (5 km), Caerphilly (11 km), Barry (12 km) and Risca (15 km).
Other products in Cardiff
- uPVC windows
- Aluminium windows
- Timber windows
- Alu-clad timber windows
- Casement windows
- Flush casement windows
- Tilt and turn windows
- Sash windows
- Bay and bow windows
- Fixed and picture windows
- Composite front doors
- French doors
- Sliding patio doors
- Bifold doors
- Acoustic triple glazing
- Security glazing
- Whole-house replacement
- New builds and self-builds
- Period homes and conservation areas
- Flats and apartments
- Passivhaus and EnerPHit
Glass-only replacement in Cardiff: book your free survey
Written quote fixed for the specification, after a free survey. Building Regulations sign-off by a competent person scheme installer or building control, as the law requires in Wales.
