Plastic windows are cheaper on the day you order them. Over 60 years, one university study found they were the most expensive windows you could choose.
We manufacture wooden windows, so we’re hardly neutral. That’s why we’d rather show you the evidence than ask you to trust us. Every week we quote for homeowners replacing 20- or 25-year-old plastic units, and the same three questions come up. How long will the new ones last? What will they cost over the years? Will the council care? This guide answers all three with primary sources, our own supply prices and the trade-offs we see on real orders. Where plastic is the better choice, we’ll say so.
Timber: 56–65 year service life
uPVC: 26–35 years
Part L: 1.4 W/m²K for both
From £449 + VAT
Supply-only, UK-wide delivery
In this guide
What You’ll Discover in This Article
- How long wood and plastic really last, and the study behind the numbers
- A comparison of costs that runs past the first invoice
- What Part L asks of replacement windows, and why both materials can pass
- Where planning rules leave you a choice in period properties, and where they don’t
- When plastic is the sensible call (there are cases)
01 · The materials
Timber vs uPVC Windows: How the Two Materials Differ
Both materials can make a good window. The difference lies in what the window is made of and what happens to it over decades.
What Each Frame Material Is Made Of
uPVC is unplasticised polyvinyl chloride, extruded into hollow chambers and usually stiffened with steel inside. Wooden profiles are cut from solid or laminated sections. Ours are engineered pine, engineered meranti or solid European oak. Every section is made from timber that’s kiln-dried and glued in layers, so it stays straight and stable.
How We Make Our Windows
Each order is made to measure. We machine the profiles, bed the sealed units and spray the paint in our workshop before anything leaves. Our lead time is around 20 working days, and delivery is booked as soon as the joinery is finished. Your own installer, ideally FENSA-registered, then fits the windows on site.
Where Aluminium Windows Fit In
Metal sits at a third price point. It’s slim and durable, but it conducts heat far more readily than wood or plastic, so it relies on thermal breaks. Most period-house owners we speak to are choosing between the two materials in this guide. So that’s where we’ve kept the focus.
02 · Service life
Lifespan, Repair and Carbon Footprint
Service life is where the two materials part company. It drives almost every other number in this article.
What the Heriot-Watt Study Found
The most detailed UK comparison is a 2013 whole-life analysis by Heriot-Watt University, published by the British Woodworking Federation. It was commissioned by the Wood Window Alliance, a trade body for wooden window makers, so read it with that in mind. Using the ISO 15686 service life method, it put factory-finished timber frames at 56 to 65 years in average UK conditions. PVC-U came out at 26 to 35 years. That’s roughly two sets of plastic for every set made of wood.
Why Repair Beats Replacement
A rotten sill or a split bottom rail on a wooden sash can be cut out and spliced by a joiner. A cracked corner weld on uPVC frames usually can’t be repaired economically, so the whole unit goes. In our experience, that’s the real reason these windows can last so long. They’re built to be maintained, not discarded.
Embodied Carbon Over 60 Years
Wood stores the carbon the tree absorbed while it grew. The same Heriot-Watt work found that each window made of wood to the trade body’s specification saves around 160 kg CO₂e over its life compared with a PVC-U equivalent. Across a typical house, that adds up to roughly 1.5 tonnes. Most of a window’s environmental cost comes from making it, so the fewer replacements, the better.
Responsibly Sourced Timber and End of Life
Timber is renewable when it comes from managed forests, so ask any supplier for chain-of-custody evidence such as FSC or PEFC certification. At the end of their working life, timber window frames can be recycled or burned for energy. PVC-U can be recycled too, but it needs a dedicated collection route.
03 · Cost
Price and a 60-Year Cost Comparison
uPVC has the lower initial cost. That part of the debate between timber and plastic isn’t in dispute.
Supply Price Per Window
Our sash windows on hidden springs start at £449 + VAT, and our flush casement windows start at the same figure. Larger sizes, divided panes and oak raise the price; you’ll find our current supply prices online. Fitting is arranged separately with your installer. In our experience it adds 40–60% on top of the joinery, depending on access and making good. When you compare uPVC quotes, a plastic unit is usually cheaper to buy, often by a wide margin.
Whole-Life Cost: Wood and Plastic Side by Side
Price is only one row. The table sets out how uPVC and timber compare over a 60-year horizon.
| Wood (factory-finished) | uPVC | |
|---|---|---|
| Expected service life | 56–65 years | 26–35 years |
| Purchase price | Higher | Lower |
| Replacements in 60 years | Usually none | At least one |
| Routine care | Wash; recoat exterior faces every few years | Wash; lubricate hardware; renew seals |
| Repairing rot or damage | Splice or patch by a joiner | Rarely economic |
| Part L (replacement windows) | 1.4 W/m²K or WER band B | 1.4 W/m²K or WER band B |
| Listed buildings | Normally expected | Rarely consented |
| Whole-life cost over 60 years | Lower | Highest of the materials tested |
When uPVC Is the Sensible Choice
We’d choose uPVC ourselves in a few situations. If you’re selling within five years, or a rental needs the cheapest compliant window, plastic can be the more cost effective option. The same goes for a 1990s house that’s plastic throughout and has no period detail. The pros and cons of uPVC depend heavily on how long you’ll own the house.
04 · Energy & Part L
Energy Efficiency, Noise and Part L
On thermal performance, the gap is smaller than either side’s marketing suggests.
What Part L Asks of Replacement Windows
In England, Approved Document L limits replacement windows to 1.4 W/m²K or a Window Energy Rating of band B. Windows made of wood had a transition allowance of 1.6 W/m²K until 14 June 2023. Since 15 June 2023, they’ve had to meet the same 1.4 figure as every other material. Our sash on hidden springs reaches 1.4 W/m²K with a warm edge spacer. Wales and Scotland set their own rules.
The Natural Insulating Properties of Wood
Wood is a poor conductor of heat, so the inside face feels warm on a cold morning. Plastic profiles get similar results through internal air chambers. In practice the glass does most of the work, which is why both can meet the same standard. Good insulation around the opening and a well-sealed fit matter just as much.
Two Panes or Three?
Our standard units have two panes, and you can read more about our insulated glass options. We also offer triple glazing. It suits exposed or north-facing walls, but it adds weight, so on sashes we check the balances can carry it. For most period houses, a good two-pane unit is the better balance of energy efficiency, weight and slim sightlines.
Acoustic Windows and Street Noise
Noise is often a bigger complaint than heat in London terraces. Acoustic units use laminated glass with a sound-damping interlayer, and they work in either material. Wood’s density helps a little. Airtight seals and the quality of the fit make the larger difference, and that part sits with your installer.
05 · Upkeep
Maintenance: The “Low-Maintenance” Question
Neither material is maintenance-free, whatever the brochure says.
Factory Finishes and Repainting Cycles
Our joinery leaves the workshop with a microporous paint system sprayed in controlled conditions. That lasts far longer than a brush coat applied on site. Wash the paintwork once or twice a year and recoat exterior faces every few years, depending on exposure. South- and west-facing elevations need attention first. The joinery carries our 5-year guarantee.
What Plastic Upkeep Actually Involves
PVC-U is often marketed as a low-maintenance option, and day to day it is. Whereas uPVC can’t be sanded and repainted like wood, a specialist can respray it, and seals, hinges and handles can be swapped. Sealed units fail eventually in both materials. The difference shows after 25 or 30 years, when a standard uPVC unit that’s become brittle or discoloured has to be replaced rather than repaired.
Who Carries Out Repairs
We’re a supply-only manufacturer, so on-site work is done by others. A local joiner or sash window specialist handles splicing, re-cording and draught-proofing on wooden sashes. For plastic units, the original installer or a repair firm replaces hardware and units. Both trades are worth finding before you need them.
06 · Planning
Sash Windows, Period Properties and Planning
In older houses, appearance often settles the question before cost does.
Listed Buildings and Consent
Replacing the windows of a listed building normally needs listed building consent, and councils rarely approve plastic. Historic England’s guidance on traditional windows asks owners to repair first and replace like for like only when a window is beyond repair. That makes real timber the expected choice. Our page on replacing windows in listed buildings explains the process.
Conservation Area Rules and Article 4
Conservation status doesn’t, on its own, stop a homeowner choosing plastic for a house. Permitted development allows replacement windows of similar appearance, and plastic can qualify. What changes things is an Article 4 direction. Many councils use one to bring front-elevation windows back under planning control. Check with your local planning authority before you order. These rules apply in England.
uPVC Sash Windows vs Wooden Sash Windows
Modern uPVC sash windows have improved, but the profiles are still bulkier and the horns are often moulded on. Woodgrain foils imitate real wood without quite matching it. Wooden sash windows keep the slim meeting rails and run on weights or spiral balances, as true sliding sash windows. On a Victorian or Georgian street, you can see the difference from the pavement.
Matching the Window Style
Whatever you choose, match the style to the house: pane pattern, bar layout, horn shape and colour. New sash windows for your home should copy the originals on your street, not a catalogue. Getting those details right adds more to a period home than any brochure claim.
07 · Example project
Case Study: Wandsworth, Victorian Terrace
This is an example project, typical of the orders we supply to south-west London.
The owners of a Victorian terrace in Wandsworth had lived with plastic sashes fitted around 2000. Three units had misted, two handles had snapped, and the front looked flat next to the neighbours’ painted sashes. The original box frames had gone during that earlier replacement. So we specified sashes on concealed spiral balances, which need a shallower outer box.
Specification:
- 6 bespoke timber sash windows on hidden springs, engineered pine
- 2-over-2 pane pattern copied from an original window two doors down
- Factory finish: Farrow & Ball All White
- Double glazing with warm edge spacers
- Brass fasteners and sash lifts
Project numbers:
- Joinery supply cost: £6,900 + VAT
- Lead time: around 20 working days
- Delivery: booked on completion, UK-wide
- Client’s installer: FENSA-registered joiner
- Installation duration on site: 5 working days
- Approximate total project cost (joinery + installation): £10,400
- U-value: 1.4 W/m²K per window
On a project like this, the house gets its original pane pattern back, the new sashes meet Part L, and the joinery shouldn’t need replacing for decades. The installer’s FENSA certificate covers building regulations, which matters when the house is sold.
Frequently Asked Questions
Are timber windows better than uPVC windows?
–
+
For long-term owners, usually yes. Factory-finished wooden windows last 56–65 years against 26–35 for PVC-U, can be repaired, and suit period houses. Plastic is cheaper to buy and needs less routine care, which suits short ownership or rentals.
How long do uPVC windows last compared with wood?
–
+
The Heriot-Watt University study put PVC-U at 26–35 years and factory-finished wood at 56–65 years in average UK conditions. Over 60 years, you’d expect to replace plastic windows at least once.
Which is more energy efficient, timber or uPVC?
–
+
Both can meet the Part L limit of 1.4 W/m²K for replacement windows, because the glass and spacer do most of the work. Wood is a natural insulator; plastic relies on internal chambers. Our sash on hidden springs reaches 1.4 W/m²K.
Can I use uPVC in a conservation area?
–
+
Often you can, unless an Article 4 direction removes permitted development for windows or the house is listed. Councils look for a similar appearance to the existing windows. Always confirm with your local planning authority before ordering.
Do you install the windows?
–
+
No. We’re a supply-only manufacturer: we make and deliver bespoke timber windows and doors nationwide. Your builder, joiner or a FENSA-registered installer fits them. We’re happy to supply the drawings and specifications they need.
Summary
Conclusion: Judge Windows Over Decades, Not on Order Day
uPVC wins on purchase price, and in some homes that’s the right priority. Over the life of a house, the evidence points the other way. Wood lasts roughly twice as long, it can be repaired, and in period streets it’s often what planners expect.
If you plan to stay, compare timber and uPVC on lifetime cost rather than the first invoice, and choose timber. Quality timber windows, properly finished and well fitted, should outlast most mortgages.
Request a free quote today and send us your opening sizes. We’ll specify timber replacements for your uPVC windows.
Our Best-Selling Timber Windows:
