In this article, you’ll discover: Introduction Arched windows make statements. Whether it’s a Gothic pointed arch in a church conversion, a Romanesque curve in a Victorian villa, or a subtle segmental arch adding character to a cottage, curved windows create architectural interest that rectangular openings simply can’t match. But arched windows are genuinely challenging to […]
In this article, you’ll discover: Introduction “I want hardwood windows” is something we hear weekly. But hardwood isn’t a single material — it’s a category containing dozens of species with dramatically different properties. Oak and meranti are both hardwoods, yet they differ in durability, appearance, workability, cost and environmental impact. Choosing the wrong species wastes […]
https://timberwindows-direct.co.uk/wp-content/uploads/2018/01/West-London-5.jpg720960Michal Plonskihttps://timberwindows-direct.co.uk/wp-content/uploads/2017/06/TWD-logo-small.pngMichal Plonski2026-02-13 10:19:002026-02-15 11:23:23Hardwood Windows: The Complete Species Comparison Guide
In this article, you’ll discover: Introduction Arched windows make statements. Whether it’s a Gothic pointed arch in a church conversion, a Romanesque curve in a Victorian villa, or a subtle segmental arch adding character to a cottage, curved windows create architectural interest that rectangular openings simply can’t match. But arched windows are genuinely challenging to […]
In this article, you’ll discover: Introduction “I want hardwood windows” is something we hear weekly. But hardwood isn’t a single material — it’s a category containing dozens of species with dramatically different properties. Oak and meranti are both hardwoods, yet they differ in durability, appearance, workability, cost and environmental impact. Choosing the wrong species wastes […]
https://timberwindows-direct.co.uk/wp-content/uploads/2018/01/West-London-5.jpg720960Michal Plonskihttps://timberwindows-direct.co.uk/wp-content/uploads/2017/06/TWD-logo-small.pngMichal Plonski2026-02-13 10:19:002026-02-15 11:23:23Hardwood Windows: The Complete Species Comparison Guide
The main arch styles and their architectural origins
How curved timber windows are actually manufactured
Realistic lead times and cost premiums for arched windows
Which properties suit arched window designs
Key specification considerations for curved glazing
Introduction
Arched windows make statements. Whether it’s a Gothic pointed arch in a church conversion, a Romanesque curve in a Victorian villa, or a subtle segmental arch adding character to a cottage, curved windows create architectural interest that rectangular openings simply can’t match.
But arched windows are genuinely challenging to manufacture well. The curves demand different construction techniques, specialist skills, and longer production times. That translates to higher costs and longer lead times — typically 40-60% more expensive than equivalent square-headed windows, with 10-14 week delivery rather than 6-8 weeks.
We manufacture bespoke timber windows including arched designs for properties across the UK. This guide explains what’s involved: the different arch types, how they’re made, what they cost, and whether they’re right for your project.
Arch Types: Gothic, Romanesque and Segmental
Different arch shapes suit different architectural contexts. Understanding the options helps you specify appropriately.
Gothic Arches (Pointed)
Gothic arches come to a point at the apex, created by two arcs meeting at an angle. They’re the defining feature of medieval ecclesiastical architecture and remain common in church conversions, Victorian Gothic revival buildings, and properties with religious origins.
The pointed profile creates a distinctive vertical emphasis. Gothic arches suit:
Church and chapel conversions
Victorian Gothic revival properties
Buildings with existing Gothic architectural features
Statement feature windows where drama is intended
Gothic arches are the most complex to manufacture due to the compound curves meeting at the apex.
Romanesque Arches (Semi-circular)
Romanesque arches form a perfect semicircle — the simplest curved form geometrically. They predate Gothic architecture and remain common in Norman buildings, Georgian architecture, and classical revival styles.
The rounded profile creates a softer, more classical appearance. Romanesque arches suit:
Georgian and Regency properties
Classical revival buildings
Norman or Romanesque historic structures
Situations requiring elegant simplicity
Semi-circular arches are easier to manufacture than Gothic pointed arches because the curve is uniform throughout.
Segmental Arches (Shallow Curve)
Segmental arches are shallow curves — less than a semicircle. They’re the most common arch type in domestic British architecture, appearing on countless Victorian and Edwardian properties where a subtle curve adds character without dramatic statement.
The shallow profile creates gentle visual interest without dominating. Segmental arches suit:
Victorian terraces and semis
Edwardian properties
Cottages and traditional homes
Any property where subtle detailing is preferred
Segmental arches are the most straightforward curved windows to manufacture.
Comparison Table
Arch Type
Profile
Complexity
Best Application
Gothic
Pointed apex
High
Church conversions, Gothic revival
Romanesque
Perfect semicircle
Medium
Georgian, classical, Norman
Segmental
Shallow curve
Lower
Victorian, Edwardian, cottages
Manufacturing Curved Timber Windows
Arched windows require fundamentally different construction approaches than rectangular windows.
Laminated Curved Sections
The standard method for curved timber frames uses lamination. Thin strips of timber are glued together over a curved former, creating a solid curved section once the adhesive cures.
Laminated construction offers several advantages:
Strength: Laminated curves are stronger than solid timber bent to shape
Stability: The alternating grain directions resist warping
Precision: Accurate curves can be achieved consistently
Any radius: Both tight curves and gentle arcs are possible
The process requires accurate formers (expensive for one-offs) and extended production time for adhesive curing. This explains much of the cost premium.
Solid Timber Curves
For gentle curves like segmental arches, solid timber can sometimes be used. The curve is cut from a larger section of timber, with grain running as close to parallel with the curve as possible.
This works for shallow curves but becomes impractical for tighter radii — too much cross-grain weakness and too much waste.
Glazing Considerations
Curved openings present glazing challenges:
Curved glass is possible but expensive. True curved glass (bent while hot) costs significantly more than flat glass and requires specialist suppliers. Most curved windows use flat glass in curved frames.
Faceted glazing approximates curves using multiple small flat panes. This works well for Romanesque and Gothic designs where traditional glazing patterns would have used small panes anyway.
Single curved pane with flat glass sits in the curved frame with a slight gap at the curve extremes. Acceptable for gentle segmental arches but noticeable on tighter curves.
Lead Times and Costs
Arched windows require longer production schedules and command premium pricing.
Typical Lead Times
Standard rectangular windows: 6-8 weeks
Segmental arch windows: 10-12 weeks
Gothic and Romanesque arches: 12-14 weeks
Complex bespoke curved designs: 14-16+ weeks
The extended timeline reflects former creation, lamination curing time, and the additional handwork required for curved sections.
Cost Premiums
Expect arched windows to cost 40-60% more than equivalent square-headed windows. For complex Gothic designs or very tight curves, premiums can reach 80-100%.
A segmental arch casement that might cost £600 as a rectangular window typically costs £840-£960 as an arched version. A large Gothic arch feature window can easily exceed £2,000-£3,000.
Factors Affecting Arched Window Costs
Curve complexity: Gothic more than Romanesque more than segmental
Size: Larger arches require larger formers and more material
Glazing pattern: Multiple panes add complexity
Opening mechanism: Fixed lights cost less than opening sashes
Arched windows suit specific contexts. Using them inappropriately looks awkward regardless of manufacturing quality.
Church and Chapel Conversions
The obvious application. Gothic and Romanesque arches are architecturally authentic for religious buildings. Replacement windows should match original profiles exactly — planning authorities and conservation officers expect accuracy.
Victorian Gothic Revival Properties
Many Victorian buildings incorporated Gothic detailing — pointed arches, tracery patterns, ecclesiastical references. Arched windows complement this existing character.
Georgian Properties and Feature Windows
Romanesque (semicircular) arches suit Georgian architecture’s classical references — fanlights over doors, Venetian windows, and decorative arch-topped features. Beyond period accuracy, a single arched window can create a focal point at a staircase landing or illuminating a double-height space. Used sparingly, arches add character without overwhelming.
Period Property Restoration
Where original arched windows survive but need replacement, matching the existing profile maintains architectural integrity. Listed buildings and conservation areas typically require accurate reproduction.
Specification Considerations
Getting arched window specifications right prevents expensive mistakes.
Measuring Curved Openings
Accurate measurement is critical. Unlike rectangular openings where width and height suffice, curved openings need:
Overall width at widest point
Overall height from sill to apex
Curve profile (radius for simple curves, or template for complex shapes)
Spring point (where curve begins)
For complex arches, a cardboard template of the opening is often the safest approach. We can work from photographs and measurements, but templates eliminate ambiguity.
Glazing Bar Patterns
Arched windows historically featured glazing bars following the curve. Georgian-style patterns might include radial bars fanning from the centre, while Gothic designs often incorporated tracery.
Modern sealed glazing units make complex patterns expensive. Consider whether elaborate glazing bars are necessary or whether simpler patterns achieve similar effect.
Hardware and Operation
Arched-top windows are often fixed lights with rectangular opening sections below. This simplifies hardware — curved opening sashes require specialist hinges and stays.
Where opening arched sashes are essential, budget additional time and cost for bespoke hardware solutions.
Frequently Asked Questions
How much more do arched windows cost than rectangular?
Expect 40-60% premium for most arched designs. Simple segmental arches sit at the lower end; complex Gothic designs reach 80-100% premium. A rectangular casement costing £600 might cost £840-£960 as a segmental arch, or £1,080-£1,200 as a Gothic arch. These premiums reflect manufacturing complexity, not profit margins.
Can any window company make arched windows?
No. Curved window manufacture requires specialist equipment, skills and experience. Many window companies decline arched work or subcontract it. Ask specifically about arched window experience, request examples of previous curved work, and expect longer lead times. Manufacturers who regularly produce curved windows achieve better results than those attempting occasional one-offs.
What’s the lead time for arched timber windows?
Typically 10-14 weeks compared to 6-8 weeks for rectangular windows. Complex Gothic designs or bespoke curves may extend to 14-16 weeks. The additional time covers former creation, lamination curing, and the extra handwork curved sections require. Plan your project timeline accordingly — arched windows shouldn’t be specified at the last minute.
Do arched windows need planning permission?
Same rules as any window replacement. Like-for-like replacement of existing arched windows is usually permitted development. Changes to arch profiles, or installing arched windows where rectangular existed, may require planning approval in conservation areas and always require Listed Building Consent for listed properties. Check with your local planning authority before committing.
Can arched windows be double or triple glazed?
Yes, though with some considerations. Curved sealed units are possible but expensive. Most arched windows use flat glass within curved frames — acceptable for gentle curves but noticeable on tight radii. For maximum thermal performance with arched designs, discuss glazing options during specification. Argon-filled double glazing works well in most arched configurations.
Conclusion
Arched timber windows add genuine architectural distinction to appropriate properties. Gothic arches suit ecclesiastical conversions and Victorian Gothic revival buildings. Romanesque semicircles complement Georgian and classical architecture. Segmental arches provide subtle character for Victorian terraces and cottages.
The premium pricing and extended lead times reflect real manufacturing complexity. Curved windows can’t be rushed without compromising quality. Budget appropriately, plan timelines realistically, and choose a manufacturer with genuine curved window experience.
At Timber Windows Direct, we manufacture bespoke arched windows in all configurations — Gothic, Romanesque, segmental and bespoke curves. Every window is made to order using laminated construction for strength and accuracy. Request your free quote and let’s discuss your arched window requirements.
How oak, accoya, meranti, iroko and sapele actually compare
Durability ratings and what they mean for real-world performance
Why the most expensive hardwood isn’t always the best choice
Sustainability credentials for each species
Realistic cost comparisons and warranty expectations
Which hardwood suits your specific project
Introduction
“I want hardwood windows” is something we hear weekly. But hardwood isn’t a single material — it’s a category containing dozens of species with dramatically different properties. Oak and meranti are both hardwoods, yet they differ in durability, appearance, workability, cost and environmental impact.
Choosing the wrong species wastes money. Choosing the right one means windows that last generations.
The challenge? Most information online is either oversimplified (“oak is best”) or buried in forestry jargon that doesn’t help homeowners make practical decisions. This guide cuts through both problems.
We’ve manufactured timber windows in several major hardwood species. We know how each machines, how each finishes, and how each performs in British weather over years and decades. Here’s what actually matters when comparing hardwood windows.
Understanding Durability Classifications
Before comparing individual species, you need to understand how durability is measured. The European standard EN 350 classifies timber into five durability classes based on resistance to fungal decay.
The EN 350 Durability Scale
Class
Rating
Typical Lifespan (Exterior)
Examples
1
Very durable
25+ years untreated
Teak, iroko
2
Durable
15-25 years untreated
Oak, meranti (some)
3
Moderately durable
10-15 years untreated
Pine (some), sapele
4
Slightly durable
5-10 years untreated
Spruce
5
Not durable
<5 years untreated
Beech, birch
Here’s what many suppliers won’t tell you: these ratings assume untreated timber in ground contact. For windows — which are above ground, protected by design, and always finished — even Class 3 timbers perform excellently. The classification matters, but it’s not the whole story.
What Really Affects Window Longevity
Three factors matter more than raw durability class:
Design. Water must drain, not pool. Proper weathering details, adequate drip grooves, and sensible sill design matter enormously.
Finish. Quality microporous paint systems protect the timber from moisture while allowing it to breathe. Factory-applied finishes outperform site-applied alternatives.
Maintenance. Any hardwood window will fail eventually if paint breakdown is ignored. Any hardwood window will last generations with basic periodic care.
Oak: The Traditional British Choice
Oak is the default hardwood in most people’s minds — and for good reason. European oak (Quercus robur and Q. petraea) has been used for British buildings since medieval times.
Properties and Performance
Oak offers exceptional natural durability (EN 350 Class 2). The dense grain structure resists moisture penetration and fungal attack without chemical treatment. Properly maintained oak windows routinely last 60-80 years; many survive far longer.
The wood machines well but requires sharp tooling — oak is hard and can blunt cutters quickly. It accepts all finish types, from traditional linseed oil to modern microporous paints.
Appearance
Oak has distinctive grain with prominent medullary rays visible on quartersawn surfaces. Colour ranges from pale straw to mid-brown depending on origin. Left unfinished, oak silvers to an attractive grey patina over years.
Sustainability
European oak is generally well-managed and widely available from FSC or PEFC certified sources. It’s a genuinely sustainable choice when responsibly sourced.
Cost and Value
Oak commands premium pricing — typically 50-70% more than engineered softwood and 30-40% more than meranti. For period properties, heritage restoration, and homeowners prioritising maximum longevity, that premium is usually justified.
Best for: Listed buildings, heritage properties, conservation areas, maximum lifespan priority, traditional aesthetics.
Meranti: The Practical Hardwood
Meranti has become increasingly popular as a middle-ground option — hardwood performance at a more accessible price point.
Properties and Performance
Meranti’s durability varies by species within the Shorea genus. Dark red meranti typically achieves EN 350 Class 2-3, offering 40-50 year lifespans with proper maintenance. It’s more dimensionally stable than oak, which makes it excellent for precision joinery.
The timber machines beautifully — clean cuts, minimal tearing, excellent screw-holding capacity. It accepts finishes well and rarely causes problems during manufacturing.
Appearance
Meranti has a straighter, more uniform grain than oak. Colour ranges from pale pink to deep reddish-brown. It doesn’t have oak’s distinctive character, but many homeowners prefer the cleaner, more consistent appearance.
Sustainability
This requires attention. Meranti comes from Southeast Asian tropical forests where illegal logging remains a problem. Always verify FSC certification and supply chain traceability. Reputable suppliers can demonstrate legal, sustainable sourcing — ask for documentation.
Cost and Value
Meranti typically costs 20-30% more than engineered softwood but 30-40% less than oak. For conservation areas where hardwood appearance is preferred but budgets are realistic, meranti hits the sweet spot.
Best for: Conservation areas, mid-range budgets, clean modern aesthetics, dimensional stability priority.
Accoya: Modified Wood, Exceptional Performance
Accoya isn’t a species — it’s a branded modified wood product. Radiata pine undergoes acetylation, a non-toxic process that permanently changes the wood’s cell structure to achieve Class 1 durability.
Properties and Performance
Accoya achieves durability ratings matching or exceeding teak. The modification process makes the timber extremely dimensionally stable — it barely moves with moisture changes. This translates to windows that maintain tight tolerances, seals that stay effective, and paint finishes that last longer.
Appearance
Accoya looks like the Radiata pine it’s made from — pale, straight-grained, uniform. It doesn’t have the character of oak or the warmth of meranti. Most Accoya windows are painted rather than stained.
Sustainability
Accoya scores highly on sustainability. The base timber comes from FSC-certified fast-growing plantations. The acetylation process uses acetic acid (essentially vinegar) with no toxic chemicals. And the exceptional longevity means fewer replacement cycles over a building’s lifetime.
Cost and Value
Accoya commands premium pricing similar to oak. The justification is longevity, dimensional stability, and sustainability credentials rather than traditional aesthetics.
Best for: Exposed coastal locations, sustainability priority, maximum dimensional stability, contemporary designs, clients who value warranties.
Iroko: African Durability
Iroko (Milicia excelsa) is sometimes called “African teak” — a comparison that’s broadly accurate for durability if not botanical accuracy.
Properties and Performance
Iroko achieves EN 350 Class 1-2 durability — genuinely exceptional. It contains natural oils that resist moisture and fungal attack without treatment. The timber is hard-wearing and performs excellently in exposed locations.
However, iroko can be challenging to machine. Interlocked grain causes tearing, and the natural oils can affect paint adhesion. It requires experienced manufacturing.
Appearance
Iroko has a warm golden-brown colour that darkens over time. Grain is typically interlocked with a medium texture. It’s attractive but lacks oak’s distinctive character.
Sustainability
Iroko availability has declined due to overharvesting. FSC-certified sources exist but require careful verification. Some specifiers now avoid iroko on sustainability grounds, preferring meranti for comparable durability.
Cost and Value
Iroko sits between meranti and oak on price. Given sustainability concerns and manufacturing challenges, we generally recommend alternatives unless iroko is specifically required.
Best for: Very exposed locations, clients who specifically want iroko aesthetics, situations where exceptional untreated durability matters.
Sapele: The Mahogany Alternative
Sapele (Entandrophragma cylindricum) offers mahogany-like aesthetics at a lower price point. It’s popular for high-end joinery including windows.
Properties and Performance
Sapele achieves EN 350 Class 3 durability — moderately durable. That’s lower than oak or iroko, but perfectly adequate for well-designed, well-finished windows. Expect 35-45 year lifespans with proper maintenance.
The timber machines reasonably well, though interlocked grain requires care to avoid tearing. It accepts finishes well and produces attractive results.
Appearance
Sapele has a rich reddish-brown colour with distinctive ribbon-stripe figure on quartersawn surfaces. It’s genuinely beautiful timber that many homeowners prefer aesthetically to oak.
Sustainability
Sapele faces similar concerns to other African hardwoods. FSC certification is available and should be required. Supply chain verification matters.
Cost and Value
Sapele typically costs slightly less than meranti. For homeowners prioritising aesthetics and willing to accept slightly lower durability ratings, it’s worth considering.
Best for: Stained finishes showcasing natural beauty, mahogany aesthetics, protected locations, aesthetic priority over maximum durability.
Species Comparison Table
Species
Durability Class
Typical Lifespan
Relative Cost
Stability
Best Application
Oak
2
60-80 years
££££
Good
Heritage, listed buildings
Meranti
2-3
40-50 years
£££
Very good
Conservation areas, all-rounder
Accoya
1
50+ years
££££
Excellent
Coastal, exposed, contemporary
Iroko
1-2
50-60 years
£££-££££
Good
Very exposed locations
Sapele
3
35-45 years
££-£££
Good
Stained finishes, protected locations
How to Choose the Right Hardwood
Matching species to application prevents expensive mistakes.
For Listed Buildings and Heritage Restoration
Oak is almost always the appropriate choice. Planning authorities expect historically accurate materials, and oak was the traditional hardwood for quality joinery. The premium cost is justified — and often required.
For Conservation Areas
Meranti or oak both work well. If budget permits, oak provides maximum authenticity. If budget is realistic, meranti offers hardwood appearance at lower cost. Either satisfies most conservation officers.
For Exposed or Coastal Locations
Accoya excels here. Its exceptional dimensional stability handles the constant moisture cycling of coastal environments better than any natural hardwood. Iroko is an alternative if you prefer natural timber.
For Modern Architectural Projects
Accoya’s clean appearance and sustainability credentials suit contemporary designs. Painted finishes work better than stained on most hardwoods anyway, making accoya’s plain grain irrelevant.
For Maximum Value
Meranti delivers hardwood performance at the most accessible hardwood price point. If you want engineered timber performance with hardwood durability, meranti is typically the answer.
Frequently Asked Questions
What’s the most durable hardwood for windows?
Accoya and iroko both achieve EN 350 Class 1 durability — the highest rating. In practical terms, properly maintained oak, meranti, accoya and iroko all last 40-60+ years. Design quality, finish specification and maintenance consistency matter more than raw durability class. Don’t choose purely on durability class.
Is oak worth the extra cost?
For heritage properties, listed buildings and conservation areas where authenticity matters, yes. For modern homes where appearance is less constrained, meranti or accoya often provide better value. Oak makes sense when traditional aesthetics or maximum lifespan are priorities. It makes less sense when other species perform equally well for your application.
How do hardwood windows compare to engineered softwood?
Hardwoods offer greater natural durability and typically require less frequent maintenance. Engineered softwood offers excellent dimensional stability at lower cost. For most modern applications, engineered softwood performs admirably at 30-40% lower cost. Hardwood makes sense for conservation areas, period properties, or homeowners prioritising maximum longevity.
What about tropical hardwood sustainability?
Sustainability varies enormously. Always require FSC or PEFC certification with chain-of-custody documentation. Meranti and sapele are sustainable when properly sourced; illegally logged timber remains a problem in some supply chains. Accoya offers an alternative: exceptional durability from sustainably managed softwood plantations. Ask your supplier for certification evidence.
Do hardwood windows need different maintenance than softwood?
The maintenance process is identical: inspect annually, touch up damage promptly, full redecoration every 8-15 years. Hardwoods typically extend the interval slightly — their denser structure holds finishes longer. But the principle remains: any timber window needs periodic attention. The advantage of hardwood is greater forgiveness if you delay maintenance slightly.
Which hardwood is best for painted finishes?
Oak, meranti and accoya all accept paint well. Sapele and iroko can be more challenging — their interlocked grain and natural oils sometimes affect adhesion. For painted windows, accoya’s uniform texture provides the cleanest results. For stained finishes showcasing natural grain, sapele or oak are superior choices.
What warranties should I expect on hardwood windows?
Quality manufacturers offer 5-20 year warranties depending on species and specification. Accoya products typically carry 20-year warranties due to the modification process. Warranty length matters less than warranty terms — read the conditions carefully. Warranties requiring annual professional inspection may not represent genuine confidence in the product.
Conclusion
Hardwood windows represent a long-term investment in your property. Oak delivers traditional aesthetics and maximum longevity. Meranti offers hardwood performance at an accessible price. Each has its place.
The right choice depends on your property type, location, aesthetic preferences and budget. Conservation areas typically need oak or meranti. Exposed locations suit accoya or iroko. Modern projects can choose based on sustainability and value criteria.
At Timber Windows Direct, we manufacture bespoke hardwood windows in oak and meranti — made to order for your specific openings with factory-applied finishing. Our team can advise on species selection based on your project requirements.
Get your free quote and let’s discuss which hardwood works best for your windows.
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