Key Takeaways:
- Curtain walling is a non-loadbearing glazed facade hung from the building structure, while cladding is an opaque external skin fixed directly to it — they protect buildings in fundamentally different ways.
- Post-Grenfell regulations ban combustible materials in external walls of buildings over 18 metres, affecting both systems — but cladding carries higher fire risk due to cavity design and material variety.
- Curtain walling costs £300–£900 per m² and delivers maximum natural light; cladding costs £150–£600 per m² and achieves better thermal insulation at 0.15–0.35 W/m²K.
- Many modern UK buildings use hybrid facades — curtain walling on prominent street-facing elevations with cladding on secondary or upper-level walls.
- Both systems must comply with Approved Document B for fire safety and Approved Document L for thermal performance, with BS 8414 testing required for high-rise external wall assemblies.
Walk through any UK city centre built or refurbished in the past decade and you will see the same pattern repeated across commercial developments: large stretches of glass at ground and podium level giving way to opaque panels above. That shift between transparency and solidity is usually where curtain walling ends and cladding begins — and understanding the difference between the two matters far more now than it did before 2017.
The Grenfell Tower fire changed the regulatory landscape for external wall systems in the UK. Both curtain walling and cladding are subject to stricter scrutiny under the Building Safety Act 2022, and specifiers, building owners, and leaseholders all need to understand how each system performs when fire safety, thermal efficiency, and long-term cost are on the table.
This guide sets out the practical differences between curtain walling and cladding, covers the fire safety regulations that now govern both, compares costs and thermal performance, and explains when to use each — including the increasingly common approach of using them together on the same building.
What Is Curtain Walling?
A curtain wall is a non-loadbearing facade system, typically made from aluminium framing and glass, that hangs from the building’s structural frame like a curtain. It does not carry any of the building’s dead or live loads — it supports only its own weight and transfers wind loads back to the primary structure at each floor slab.
Most curtain wall systems in the UK use thermally broken aluminium mullions (vertical members) and transoms (horizontal members) glazed with double or triple glazed sealed units. The two main construction methods are stick systems, where individual components are assembled on site, and unitised systems, where factory-assembled panels are craned into position. Both methods are covered in detail in our guide to aluminium curtain wall design.
Curtain walling is governed by BS EN 13830, which sets requirements for air permeability, water tightness, wind resistance, and impact resistance. For a full breakdown of how these systems perform, see our article on the advantages and disadvantages of curtain walling.
What Is Cladding?
Cladding is a broad term for any non-structural material applied to the outside of a building to form a protective and decorative external skin. Unlike curtain walling, which is predominantly glass, cladding is usually opaque and comes in a wide range of materials: metal panels, natural stone, brick slips, terracotta, timber, fibre cement, and composite panels.
The most common modern approach in the UK is rainscreen cladding, where an outer panel sits in front of a ventilated cavity and an inner layer of insulation. The cavity allows moisture to drain away while the insulation provides thermal performance. Other approaches include sealed barrier systems and mechanically fixed systems for stone and brick slips.
Because cladding encompasses so many materials and methods, there is no single governing standard. All external wall cladding must comply with the relevant parts of the UK Building Regulations, but the specific British Standards vary by material.
Key Differences Between Curtain Walling and Cladding
On the surface, the distinction is simple: curtain walling is glazed, cladding is opaque. But the differences run deeper than appearance.
Structural Attachment
Curtain walling is hung from the building’s floor slabs or structural frame using brackets that allow for thermal movement and structural deflection — it is always non-loadbearing. Cladding can be fixed directly to the structural frame, to secondary steelwork, or to masonry backing walls, and some heavyweight systems (natural stone, for example) can be partially loadbearing at lower levels.
Materials and Transparency
Curtain walling is predominantly aluminium and glass, designed to maximise transparency and natural light. Cladding offers a far wider material palette — metals, stone, brick, timber, terracotta, composites — and is primarily opaque. This difference drives most of the aesthetic, thermal, and cost comparisons between the two.
Weather Protection
Curtain wall systems manage water through pressure-equalised drainage within the mullion and transom profiles — water that penetrates the outer seal is channelled down internal drainage channels and wept out at the base. Rainscreen cladding takes a different approach, using a ventilated cavity behind the outer panels to drain water and allow air circulation to dry the system out.
Thermal Performance
This is one area where cladding has a clear advantage. A typical insulated cladding system achieves U-values of 0.15–0.35 W/m²K, comfortably exceeding the requirements of Approved Document L. Curtain walling, even with high-performance double or triple glazing, typically achieves 0.8–1.6 W/m²K. The trade-off is natural light: curtain walling floods interior spaces with daylight, reducing artificial lighting demand and improving occupant wellbeing. Good facade design balances these competing priorities.
Natural Light and Aesthetics
If your project needs maximum natural light and visual connection to the outside — a commercial reception area, a retail unit, an office floor plate — curtain walling is the natural choice. If you need a solid, textured, or traditional appearance, or if the building has large areas where windows are not needed, cladding gives you far greater design freedom across materials, colours, and textures.
Curtain Walling vs Cladding — Comparison Table
| Feature | Curtain Walling | Cladding |
|---|---|---|
| Structural role | Non-loadbearing, hung from structure | Non-loadbearing or partially loadbearing, fixed to structure |
| Primary materials | Aluminium + glass | Metal, stone, brick slips, timber, composites, terracotta |
| Transparency | High (mostly glazed) | Low to none (mostly opaque) |
| Weight | Lightweight | Varies widely (brick and stone cladding are heavy) |
| Weather management | Pressure-equalised drainage | Rainscreen cavity or sealed barrier |
| UK standard | BS EN 13830 | Various (material dependent) |
| Thermal performance | 0.8–1.6 W/m²K | 0.15–0.35 W/m²K (with insulation backing) |
| Natural light | Maximum | Minimal |
| Cost (supply + install) | £300–£900 per m² | £150–£600 per m² |
| Fire safety | Approved Doc B; spandrel panels A2-s1,d0 above 18m | Approved Doc B; combustible materials ban above 18m |
| Design flexibility | Glass types, tints, curved/faceted frames | Vast material palette, textures, traditional and modern finishes |
Fire Safety: The Post-Grenfell Comparison
This is where the curtain wall versus cladding debate gets serious. The Grenfell Tower fire in June 2017 killed 72 people and exposed catastrophic failures in how external wall systems — cladding systems specifically — were specified, tested, and installed. The regulatory changes that followed affect both curtain walling and cladding, but in different ways.
What Changed After Grenfell
The Building Safety Act 2022 introduced new duties and liabilities for anyone involved in the design, construction, and management of higher-risk buildings. Regulation 7 of the Building Regulations now bans the use of combustible materials (anything below Euroclass A2-s1,d0) in the external walls of residential buildings over 18 metres in height. This applies to both curtain wall and cladding systems.
BS 8414 fire testing — a large-scale test that subjects a full external wall assembly to a severe fire — is used to demonstrate that systems not made entirely of non-combustible materials can still meet safety standards. Both curtain walling and cladding assemblies may need to pass BS 8414 testing depending on their composition and the building’s height and use.
How Curtain Walling Performs
Curtain walling has an inherent advantage in fire safety terms because its primary materials — aluminium and glass — are non-combustible. Aluminium melts at around 660°C rather than burning, and glass is inert. The fire risk in curtain wall systems sits at the junctions: the seals between the curtain wall and the floor slabs. If fire stopping at these junctions is poorly installed or missing, fire can spread vertically between floors through the gap behind the curtain wall. This is why fire stopping at floor slab perimeters is critical and must be inspected during construction.
For buildings over 18 metres, any opaque spandrel panels within the curtain wall system must achieve a minimum fire classification of A2-s1,d0.
How Cladding Performs
Cladding systems carry a broader range of fire risks. The ventilated cavity behind rainscreen cladding can act as a chimney, allowing fire to spread rapidly upward if fire barriers within the cavity are missing or incorrectly installed. The material of the outer panel itself matters enormously — the aluminium composite material (ACM) panels with polyethylene cores used at Grenfell are now effectively banned on buildings over 18 metres.
Even with compliant materials, the combination of cavity, insulation, and outer panel creates more potential failure points than a curtain wall system. Correct specification, installation, and inspection of cavity barriers are non-negotiable for any cladding system on a building of any height, but especially above 18 metres.
The Bottom Line on Fire Safety
Neither system is automatically “safe” or “unsafe.” Both require correct specification and installation to meet Approved Document B. However, curtain walling inherently contains less combustible material and fewer concealed cavities than most cladding systems. Post-Grenfell, this distinction matters — not just for regulatory compliance, but for building insurance, lender confidence, and leaseholder peace of mind.
Cost Comparison
On a like-for-like area basis, cladding is generally cheaper than curtain walling. A standard rainscreen cladding system with metal or composite panels runs at roughly £150–£400 per m² for supply and installation. Natural stone and high-end terracotta push that up to £400–£600 per m².
Curtain walling typically costs £300–£900 per m², with the range depending on system type (stick vs unitised), glass specification, and the complexity of the design. Unitised systems carry a higher upfront material cost but save money on site installation time, particularly on taller buildings where scaffold or mast climber access is expensive.
Whole-life costs tell a slightly different story. Curtain walling has lower maintenance requirements — aluminium frames need only periodic cleaning and seal replacement. Cladding maintenance varies hugely by material: metal panels are low-maintenance, but timber cladding needs regular treatment, and natural stone may need repointing over time. For a broader look at how glazing and facade costs compare, see our guide to shop front costs.
Which Is Right for Your Project?
The choice between curtain walling and cladding is rarely either/or. Most commercial buildings in the UK use both. But understanding when each system works best helps you brief your architect and facade consultant more effectively.
When Curtain Walling Is the Better Choice
- Maximum natural light is a priority — offices, retail units, receptions, and public buildings where daylight and visual openness are important for the building’s function and occupant experience.
- Multi-storey commercial facades — curtain walling is the standard solution for floor-to-ceiling glazing across multiple levels. Our curtain wall installation service covers both stick and unitised systems.
- Modern, high-performance aesthetic — if the building’s design language calls for a sleek, transparent facade, curtain walling delivers it in a way that cladding cannot.
- Ground-floor retail or commercial glazing — shop fronts, showrooms, and restaurants benefit from the visibility and kerb appeal that full-height glazing provides, especially when combined with well-planned shop front lighting.
When Cladding Is the Better Choice
- Thermal performance is the driving requirement — on elevations where U-values need to be as low as possible (north-facing walls, residential buildings chasing Passivhaus or net-zero targets), insulated cladding outperforms curtain walling by a significant margin.
- Heritage or traditional aesthetic — brick slips, natural stone, and terracotta cladding allow modern buildings to sit comfortably within conservation areas or alongside period architecture.
- Budget constraints on secondary elevations — side and rear walls that do not need glazing can be clad more cost-effectively than curtain walled.
- Residential buildings above 18 metres — compliant cladding systems with non-combustible materials are well-established solutions for high-rise residential facades where solid walls are the predominant requirement.
Using Both Together: Hybrid Facades
Walk past almost any mixed-use development completed in the UK since 2015 and you will see hybrid facades in action. The typical pattern is curtain walling at ground and first floor (retail, reception, commercial space) transitioning to cladding on upper residential or office floors where solid walls and better thermal performance are needed.
This approach plays to the strengths of each system. The curtain walling delivers transparency and natural light at street level, while cladding above provides thermal performance and design variety. The junction between the two needs careful detailing for fire stopping and weathering, but it is well-established practice in UK construction.
Another common hybrid uses curtain walling with opaque spandrel panels at floor slab levels, giving the appearance of a fully glazed facade while hiding the structure and providing fire resistance at each floor. If your project involves aluminium shop fronts or ground-floor glazing with different facade treatment above, this is exactly the kind of project we work on regularly.
Frequently Asked Questions
What is the main difference between curtain walling and cladding?
Curtain walling is a non-loadbearing glazed facade system made primarily from aluminium and glass, hung from the building’s structure. Cladding is an opaque external skin made from a variety of materials (metal, stone, brick, composites) fixed to the building’s exterior. The fundamental distinction is transparency: curtain walling maximises natural light, while cladding provides a solid, insulated external wall.
Is curtain walling safer than cladding after Grenfell?
Curtain walling is inherently composed of non-combustible materials (aluminium and glass), which gives it an advantage over cladding systems that may use combustible insulation, cavity barriers, or panel materials. However, curtain walling is not automatically safe — fire stopping at floor slab junctions is critical. Both systems must comply with Approved Document B, and both may require BS 8414 testing on buildings over 18 metres.
Which is cheaper, curtain walling or cladding?
Cladding is generally cheaper on a per-square-metre basis, ranging from £150–£600 per m² depending on material, compared to £300–£900 per m² for curtain walling. However, whole-life costs depend on maintenance requirements, and the choice should be driven by the building’s functional needs rather than upfront cost alone.
Can you use curtain walling and cladding on the same building?
Yes, and most modern commercial and mixed-use buildings in the UK do exactly this. A common approach is curtain walling at ground level for retail or reception areas, with cladding on upper floors. The junction between the two systems requires careful fire stopping and weather detailing, but it is standard practice in UK construction.
What thermal performance does curtain walling achieve compared to cladding?
Curtain walling typically achieves U-values of 0.8–1.6 W/m²K, depending on the glazing specification. Insulated cladding systems achieve 0.15–0.35 W/m²K — roughly three to five times better. The trade-off is that curtain walling provides natural daylight, which reduces artificial lighting costs and improves occupant comfort.
What UK regulations apply to curtain walling and cladding?
Both must comply with Approved Document B (fire safety) and Approved Document L (energy efficiency). Curtain walling is additionally governed by BS EN 13830 for performance testing. The Building Safety Act 2022 introduced new duties for higher-risk buildings, and Regulation 7 bans combustible materials in external walls of residential buildings over 18 metres. BS 8414 large-scale fire testing applies to both system types where non-combustible construction cannot be demonstrated.
Does curtain walling need fire stopping?
Yes, and it is one of the most important aspects of curtain wall installation. The gap between the back of the curtain wall and the edge of each floor slab must be sealed with fire-rated cavity barriers to prevent fire and smoke spreading vertically between floors. Poor fire stopping at these junctions is one of the main fire safety vulnerabilities in curtain wall construction.
What is rainscreen cladding and how does it differ from curtain walling?
Rainscreen cladding is a specific cladding approach where an outer panel sits in front of a ventilated air cavity and an inner layer of insulation. The cavity allows moisture to drain away and the outer panel deflects the majority of rain. It differs from curtain walling in that it is opaque, provides much better thermal insulation, and uses a completely different weather management strategy based on cavity ventilation rather than pressure-equalised sealed drainage.
Talk to Us About Your Facade Project
Whether your project calls for curtain walling, cladding, or a combination of both, getting the specification right at the outset saves time, money, and compliance headaches further down the line. Understanding how the two systems compare — particularly on fire safety and thermal performance — is the first step toward a facade that works for your building and your budget.
At Huxley & Co, we are FENSA registered, CHAS accredited, and Constructionline approved, with over 20 years of experience in curtain walling, commercial glazing, and aluminium shop fronts across the UK. We work with architects, developers, and building owners to specify and install facade systems that meet current fire safety and energy regulations.
Call us on 020 7112 4849, email info@huxleyandco.co.uk, or get in touch through our website for a free consultation on your project.