Windows - Wood versus uPVC
See planning application BH2025/03024 which pursues the use of uPVC heritage sash windows.
In conservation areas such as Round Hill, window replacement is not just a practical matter. Windows play a major role in preserving the historic character of streets and buildings. This is why councils and conservation groups usually favour traditional timber windows over modern alternatives.
Brighton itself provides clear evidence that softwood sash windows can be exceptionally durable, even in a wet, windy and salty coastal environment: many Victorian and Edwardian buildings still retain original or largely original sash windows that are well over 100 years old. Crucially, most windows made in the Victorian period were softwood rather than hardwood, typically slow-grown Baltic redwood, Scots pine or pitch pine, chosen for their durability, resin content and ease of repair. When properly detailed, painted and maintained, comparable modern softwoods such as engineered European redwood, Douglas fir or modified softwoods like Accoya can offer similar longevity.
By contrast, uPVC windows have a finite service life: prolonged exposure to sunlight causes ultraviolet degradation, leading to gradual yellowing or greying, surface chalking and increasing brittleness, with visible ageing commonly occurring within 15–25 years and wholesale replacement often required within 20–30 years. Unlike timber, which can be repaired, spliced and upgraded repeatedly over its life, uPVC frames are not readily repairable once degraded, making timber sash windows a demonstrably longer-lasting and more sustainable solution in conservation areas.
Why the debate matters
Many Victorian and Edwardian houses were built with fine, slender timber sash windows. Changing these can significantly alter the appearance of a building and the wider area. Planning policies therefore aim to protect this character.
Wood (Timber) Windows
Why they are usually preferred by planners:
- They match the original historic appearance of period buildings
- Slender frames and traditional detailing are easier to achieve
- They can be repaired rather than replaced
- Often seen as adding long-term value to a property
The main drawbacks are higher initial cost and the need for regular maintenance, such as painting.
uPVC Windows
Why some homeowners consider them:
- Lower upfront cost
- Minimal maintenance
- Reasonable thermal performance
Marketing claims can be misleading: claims like “maintenance-free” usually mean: no painting required, not “no maintenance” in performance terms. In reality, uPVC still requires: cleaning, hardware lubrication, seal replacement and eventual wholesale replacement.
Standard uPVC windows often have thicker frames and modern finishes that do not reflect traditional design. Even so-called “heritage” uPVC may still be rejected if it does not closely replicate original timber windows.
In many conservation areas, uPVC windows are only sometimes accepted on rear or non-street-facing elevations, and only with planning permission.
Unlike timber: (a) uPVC frames cannot be spliced or patched (b) Structural cracks cannot be repaired invisibly (c) Distortion cannot be corrected (d) Colour ageing cannot be reversed.
They last from 20-30 years with 25 years being the point at which home-owners ask if repairs are worth it. See source. Less in exposed locations. They fail through UV damage, brittleness, distortion, seal and unit failure.
Once failures reach a certain point, replacement is the only practical option.
Sustainability
2.23 There are also concerns about the impacts on the environment of chlorine-based products such as UPVC. Studies commissioned by the BRE indicate that the energy required to manufacture a UPVC window is three times that of a softwood window, whilst only around 3% of UPVC is recycled, with the vast majority of it going to landfill. UPVC or aluminium windows often have to be completely replaced when broken, or the whole unit sent back to the factory to be repaired.
Timber windows are easier to repair and can be made and repaired by local crafts workers, thus benefiting the local economy and reducing waste landfill. But the timber industry can also cause environmental damage, if not managed appropriately. The council therefore recommends that timber is from environmentally sustainable and well-managed sources that are independently and reliably certificated. (At present the only international scheme of independent verification and certification is operated by the Forestry Stewardship Council (FSC). In the UK, the Soil Association’s ‘Woodmark’ and the ‘Qualifor’ are certification schemes run under FSC criteria).
Planning considerations
- Timber is generally the preferred material in conservation areas
- uPVC is often discouraged or refused, especially on visible elevations
- An Article 4 Direction may require permission even for minor changes
Practical advice
- Check whether your property is in a conservation area
- Find out if an Article 4 Direction applies
- Consider repairing existing timber windows where possible
- If replacing, high-quality timber sash windows usually offer the smoothest route to approval
In summary: timber windows best preserve historic character and are more likely to meet planning requirements, while standard uPVC windows may save money upfront but carry a higher risk of refusal.
Heritage uPVC Sash Windows — What to Look For
If you’re considering uPVC sash windows but want them to suit a conservation area, here are the key specification points that planners and conservation officers often check:
- Flush or slim sightlines that mimic traditional timber sash proportions (e.g., narrow meeting rails ~35–45mm).
- Replica putty lines and slim external profiles so the frames look like original timber from the street.
- Run-through sash horns or optional clip-on horns to match period detailing.
- Deep bottom rail and traditional glazing bar patterns (e.g., Georgian or astragal bars).
- Accurate joinery details (mechanical joints rather than plain welded joints where possible).
- Woodgrain foils or heritage colours such as cream, oak, green or grey to reduce the plastic look.
- High thermal performance — double or triple glazed units with low-E coatings and argon fill for good insulation.
- Security upgrades such as PAS24 or Secured by Design hardware.
These features help the uPVC windows read visually as traditional sash windows while retaining modern performance, but they still may need planning consent in conservation areas.
This page was last updated by Ted on 29-Jan-2026