Aluminium vs Timber Retrofit Double Glazing
Compare aluminium and timber retrofit double glazing for Christchurch homes, including suitability, cost, frame checks, and when replacement is better.
Ready for the details? See our dedicated timber retrofit double glazing and aluminium retrofit double glazing pages for suitability, process, and pricing.
By Sammy | Last updated: July 2026
Quick Answer: Aluminium vs Timber Retrofit
Both aluminium and timber windows can often be retrofitted with double glazing if the frames are sound, straight, dry, and suitable for the selected insulated glass unit. Aluminium retrofit is usually simpler and lower cost, while timber retrofit often needs more preparation and careful finishing.
Suitability Checklist
- Frame is straight and square, not warped or twisted — good candidate for retrofit.
- Frame is watertight with no signs of rot, corrosion, or leaks — good candidate for retrofit.
- Frame is deep enough for the selected insulated glass unit — confirmed during assessment.
- Frame no longer opens, closes, or locks properly — replacement is likely needed instead.
- Frame shows structural damage, rot, or corrosion — replacement is likely needed instead.
Cost and Labour Difference
Aluminium retrofit is usually the lower-cost option because installation is generally more straightforward and requires less preparation.
Timber retrofit often costs more, since sound timber frames need careful preparation — including checking putty, beads, and finishing — which adds labour time. The exact cost for either depends on frame size, number of windows, and site access. See our Christchurch cost guide for typical price ranges.
Aluminium Retrofit: When It Works
Existing aluminium frames can often be retrofitted if they are straight, weatherproof, and deep enough for the selected insulated glass unit. This is common in Christchurch homes built with single-glazed aluminium joinery.
Aluminium Retrofit: Limitations
Aluminium retrofit is usually the lower-cost frame type, but older non-thermally broken frames can still conduct cold through the metal, so some frame-level cold may remain even after the glass is upgraded.
Timber Retrofit: When It Works
Timber windows are often chosen for retrofit when the home has character joinery worth keeping. The frame needs to be sound, dry, and able to hold the new glazing system.
Timber Retrofit: Limitations
Timber retrofit may cost more than aluminium because preparation, putty, beads, and finishing can be more labour-intensive, and rot or movement in the frame usually needs addressing first.
When Full Replacement Is Better
Full replacement is usually the better choice when aluminium or timber frames are damaged, rotten, corroded, or structurally unsound, since no retrofit glass can compensate for a frame that has failed.
It may also suit homes wanting a complete joinery upgrade or improved thermal frame performance beyond what retrofit can offer — see our retrofit vs replacement guide for a fuller comparison.
Aluminium vs Timber Retrofit at a Glance
| Frame type | Retrofit suitability | Cost tendency | Main limitation |
|---|---|---|---|
| Aluminium | Often suitable if straight and weatherproof | Usually lower than timber | Old aluminium can still conduct cold through the frame. |
| Timber | Suitable when timber is dry, sound, and worth preserving | Usually higher than aluminium | Rot, movement, putty, beads, and finishing can add labour. |
| Damaged frames | Often not suitable | Replacement may be better | New glass cannot fix failed joinery. |
Frequently Asked Questions
Get a Christchurch Retrofit Assessment
The right answer depends on frame condition, glass size, exposure, access, and whether the existing joinery can safely carry an insulated glass unit.