Choosing windows feels like it should be straightforward. But once you start looking into materials, glazing options, opening styles, energy ratings, and security standards, it quickly becomes one of the more complex decisions in any home renovation. Get it right, and your windows become a defining feature of your home. Get it wrong, and you'll be reminded every time you look at them — or feel a draught through them.
We supply and install windows as part of our renovation projects across Leicester and the wider UK, so we've seen what works, what disappoints, and what homeowners wish they'd known before ordering. This guide covers everything you need to make the right window choice for your home renovation.
The Three Main Window Materials
Every window decision starts with material. Each has genuine strengths and trade-offs, and the right choice depends on your property style, your budget, and how much maintenance you're willing to do.
Aluminium Windows
Aluminium is the material of choice for modern and contemporary home renovations in the UK. The key advantage is strength — aluminium frames can be incredibly slim (as narrow as 38mm sightlines) while still providing exceptional structural performance. That means more glass, more light, and cleaner architectural lines.
Modern aluminium windows use thermal break technology to prevent cold bridging, making them as thermally efficient as any other material. They won't warp, rot, or fade, and they're available in virtually any colour through powder-coating or RAL colour matching.
Ultra-slim frames, maximum glass area, zero maintenance, 30+ year lifespan, full colour customisation, ideal for large openings
Higher initial cost than uPVC, not always suitable for period properties in conservation areas, professional installation essential
Timber Windows
Timber windows offer a warmth and character that no other material can quite replicate. Engineered timber (as opposed to solid timber) has largely solved the historic problems of warping and swelling, making modern timber windows remarkably stable and long-lasting. They're the natural choice for period properties, conservation areas, and anyone who wants that authentic, premium feel.
The trade-off is maintenance. Even factory-finished timber windows need repainting or re-staining every 8–10 years. The initial investment is also higher than uPVC, though comparable to aluminium. For listed buildings and many conservation areas in Leicester, timber may be the only approved material.
Beautiful natural aesthetic, excellent insulation, conservation area approved, sustainable and recyclable, can be repaired rather than replaced
Requires periodic repainting/staining, higher upfront cost, can be susceptible to moisture if maintenance is neglected
uPVC Flush Casement Windows
uPVC has come a very long way from the bulky white frames of the 1990s. Modern flush casement uPVC windows sit flat within the frame rather than protruding forward, creating a much cleaner, more traditional look that closely mimics timber. Combined with realistic woodgrain foil finishes in colours like Anthracite Grey, Chartwell Green, or Irish Oak, they're now a genuinely attractive option.
The biggest advantage remains cost — uPVC is typically 30–40% cheaper than aluminium — combined with virtually zero maintenance. For homeowners who want good-looking, efficient, secure windows without the premium price tag, uPVC flush casements are hard to beat.
Most affordable option, zero maintenance, excellent thermal performance, huge range of finishes, strong security as standard
Thicker frames than aluminium (less glass area), may not be accepted in conservation areas, shorter lifespan (20–25 years vs 30+), can't be repainted
Double Glazing vs. Triple Glazing in the UK
This is one of the most common questions we get asked, and the answer is more nuanced than the marketing would have you believe.
Double glazing with a low-emissivity (low-E) coating and argon gas fill achieves a U-value of around 1.2 W/m²K, which comfortably meets and exceeds current UK Building Regulations. For most homes, this level of insulation is perfectly sufficient and represents excellent value.
Triple glazing pushes that down to around 0.8 W/m²K — roughly 30% better insulation. The question is whether that improvement justifies the 25–35% price premium. For north-facing elevations, bedrooms, and properties in exposed locations, triple glazing makes a noticeable difference in comfort and noise reduction. For a south-facing living room that gets plenty of solar gain already, the payback is much less clear.
Our Recommendation
Rather than going triple-glazed throughout, consider a mixed approach: triple glazing on north and east-facing windows where heat loss is greatest and noise from roads is an issue, and high-performance double glazing on south and west-facing windows where you want to maximise solar gain. This gives you the best of both worlds at a sensible cost. It's the approach we recommend for most of our window replacement projects in Leicester.
Window Styles and Where They Work Best
Casement Windows
The most common style in UK homes. Side-hung or top-hung, opening outwards. Works in virtually every property type and offers excellent ventilation. Flush casement variants (where the sash sits flush with the frame rather than protruding) are far more elegant and increasingly popular in both new builds and renovations.
Sliding Sash Windows
The classic choice for Victorian and Georgian properties. Modern sliding sash windows look and operate like traditional ones but with dramatically better thermal performance, security, and ease of use. Spring-balanced rather than weight-and-pulley, they tilt inwards for easy cleaning. Essential for maintaining the character of period homes, particularly in conservation areas around Leicester.
Tilt and Turn Windows
Popular in continental Europe and increasingly specified in UK renovations. They tilt inwards at the top for secure ventilation or swing fully inwards for cleaning and maximum airflow. Particularly good for upper-floor windows where external access for cleaning is difficult.
Fixed Pane and Picture Windows
Fixed windows — ones that don't open — offer the slimmest possible frames and maximum glass area. They're ideal for framing specific views, flooding rooms with light, or creating architectural feature windows. Often used in combination with opening windows to balance light, views, and ventilation.
What Do Replacement Windows Cost in the UK?
| Window Type | Material | Cost Per Window (Supplied & Fitted) |
|---|---|---|
| Standard Casement (600 x 900mm) | uPVC | £350 – £550 |
| Standard Casement (600 x 900mm) | Aluminium | £550 – £900 |
| Flush Casement (1200 x 1200mm) | uPVC | £500 – £800 |
| Flush Casement (1200 x 1200mm) | Aluminium | £800 – £1,300 |
| Sliding Sash (typical Victorian size) | Timber | £1,000 – £1,800 |
| Sliding Sash (typical Victorian size) | uPVC | £600 – £1,000 |
| Large Picture Window (2000 x 1500mm) | Aluminium | £1,200 – £2,000 |
A full set of replacement windows for a 3-bedroom semi in Leicester typically costs between £4,000 and £7,000 for uPVC, or £7,000 to £14,000 for aluminium, depending on the number and size of openings. These figures include supply, installation, making good, and waste removal.
Energy Ratings: What Actually Matters
UK windows are rated on a scale from A++ (best) down to E. Since 2022, all replacement windows in England must achieve a minimum U-value of 1.4 W/m²K or an energy rating of at least Band C. In practice, virtually all modern windows exceed this comfortably.
The U-value tells you how quickly heat escapes through the glass. Lower is better. A single-glazed window typically has a U-value of around 5.0, standard double glazing around 1.2, and triple glazing around 0.8. But the U-value isn't the whole story — solar gain (how much warmth from sunlight the glass lets in) also matters, particularly on south-facing windows where you want to capture that free heat.
Security: Secured by Design
All reputable window manufacturers now build to PAS 24 security standards as standard, which includes multi-point locking, reinforced frames, and laminated or toughened glass options. For ground-floor and easily accessible windows, we recommend upgrading to laminated glass, which holds together when struck rather than shattering, making forced entry dramatically harder.
Look for the Secured by Design accreditation from the police initiative — it's the most reliable indicator that a window has been independently tested against real-world break-in methods.
Choosing Windows for Period Properties in Leicester
Leicester has a wonderful variety of period properties, from Georgian townhouses along New Walk to Victorian terraces in Highfields and Edwardian villas in Stoneygate. If your property is in a conservation area or is listed, your window choices may be restricted. Timber sliding sash windows are typically required for listed buildings, while conservation areas may accept high-quality uPVC or aluminium alternatives provided they closely match the original profiles.
Before committing to any window order, check with Leicester City Council's conservation team if your property might be affected. Your renovation company should handle this research as part of the project planning process — it's certainly something we take care of for every project we manage.
Making the Final Decision
The best windows for your renovation are the ones that balance aesthetics, performance, and budget in a way that suits your specific property and priorities. For a clean modern look with maximum glass and minimal frames, aluminium is unbeatable. For period authenticity and natural warmth, timber is the clear choice. And for excellent performance at a sensible price point, modern flush casement uPVC windows offer remarkable value.
Whatever you choose, invest in proper installation. Even the best window performs poorly if it's fitted badly. Gaps, incorrect sealing, and poor alignment can undo all the engineering that went into the product itself. This is why we always recommend using experienced, qualified installers — it's where the real difference in long-term performance is made.
Need Help Choosing Your Windows?
We supply and install aluminium, timber, and uPVC windows across Leicester. Book a free consultation to discuss the best options for your renovation project.
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