There are five main types of curtain wall systems used in UK commercial buildings: stick systems, unitised systems, semi-unitised systems, structural glazing, and spandrel curtain walls. Each suits different building types, budgets, and project timelines. Stick systems are the most cost-effective for smaller buildings, while unitised systems offer speed and quality for larger projects. This guide explains how each type works, where it’s used, and what to consider when choosing one.
Most people recognise a curtain wall system when they see one. Floor-to-ceiling glass wrapping a modern office block. A sleek glazed facade on a hotel or shopping centre. But few realise that curtain walling isn’t a single product. It covers several distinct systems, each engineered for different building types, project scales, and performance requirements.
Choosing the wrong system for your building can be a costly mistake. Getting it right at specification stage avoids expensive redesigns, delays, and compliance issues down the line. This guide covers the five main types of curtain wall systems, how they differ, and what drives the decision between them.
Section 01
What Is a Curtain Wall System?
A curtain wall system is a non-load-bearing external facade fitted to the outside of a building’s primary structure. It carries no structural weight from the building itself. Its job is to resist wind loads, weather, and its own self-weight, and to transfer those forces back to the main structure through anchor points at each floor level.
The Centre for Window and Cladding Technology (CWCT) defines curtain walling as “a form of vertical building enclosure which supports no load other than its own weight, that of ancillary components and the environmental forces which act upon it.” This is the key distinction between curtain walling and traditional construction, where the external walls form part of the primary structure.
Typical curtain wall systems combine a lightweight aluminium frame with large areas of glazing. Opaque infill panels, spandrel glass, metal panels, or stone cladding can also be incorporated depending on the design. The UK curtain walling market is valued at over £600 million annually, growing at 4.2% per year through to 2035, driven by commercial development, urban regeneration, and tightening energy performance standards.
For businesses looking at curtain walling installation in London, understanding the different system types is the essential first step before approaching any installer for a survey or quote.
Section 02
What Are the Main Types of Curtain Wall Systems?
The five main types of curtain wall systems are: stick systems (assembled on-site piece by piece), unitised systems (prefabricated panels installed as complete units), semi-unitised systems (a hybrid of both), structural glazing or point-fixed systems (frameless or minimal-frame glass facades), and spandrel curtain walls (which combine opaque and transparent panels). Each type suits a different building scale, budget, and design requirement.
The right system for your project depends on building height, access conditions, project timeline, energy performance targets, and budget. The sections below explain each type in detail.
Section 03
Stick Curtain Wall Systems
A stick curtain wall system is assembled on-site piece by piece. Individual vertical members (mullions) and horizontal members (transoms) are fixed to the building structure, and the glazing is inserted into the completed frame. It is the most cost-effective curtain wall option, best suited to low-to-mid-rise buildings where site access is good and installation flexibility is needed.
Stick systems are the most widely used curtain wall type in the UK, particularly for low-rise and medium-rise commercial buildings. The individual aluminium mullions and transoms are installed one at a time, connected to the floor slabs at each level, with glazing inserted from either the inside or outside depending on access conditions.
Low-to-mid-rise commercial buildings, offices, retail units, buildings with good site access
£250–£700/m² — lowest upfront cost of all curtain wall types
High flexibility during installation. Design changes can be accommodated on-site without discarding prefabricated panels.
Longer installation time than unitised. Quality is dependent on on-site workmanship and weather conditions during fitting.
Stick systems are a practical and well-understood solution. They suit projects where cost control is a priority, site access is straightforward, and the building doesn’t exceed four or five storeys. The main trade-off is time: unitised systems can be installed in roughly one third of the time compared to equivalent stick systems.
Section 04
Unitised Curtain Wall Systems
A unitised curtain wall system consists of large panels prefabricated and glazed in a factory, then delivered to site and lifted into position. Installation is significantly faster than stick systems and quality control is higher because most of the work is done under factory conditions. Unitised systems are the preferred choice for high-rise buildings and large commercial projects.
Unitised systems are the industry standard for high-rise commercial construction. Each storey-height panel is fully glazed and assembled in controlled factory conditions before being delivered to site, lifted by crane, and locked into position against the building structure.
High-rise buildings, large commercial projects, sites with restricted access, fast-track programmes
£500–£1,000+/m² — higher upfront material cost, lower on-site labour
Installation speed is roughly three times faster than stick systems. Factory quality control reduces on-site defects and rework.
Higher upfront cost. Design changes after fabrication are expensive. Requires crane access and careful sequencing on site.
For developers and contractors working on tight programmes, the speed advantage of unitised systems is significant. Labour costs shift from the site to the factory, which is particularly valuable in high-cost urban environments like London where skilled on-site labour is expensive and access is often restricted.
Section 05
Semi-Unitised Curtain Wall Systems
Semi-unitised systems sit between stick and unitised. The main aluminium profiles (mullions and transoms) are manufactured in the factory, but the glazing and other infill components are attached on-site once the framework is in place.
Medium-rise commercial and office buildings, projects requiring a balance of speed, quality, and design flexibility
£350–£750/m² — mid-range between stick and fully unitised
Faster than stick systems due to factory-made profiles. More flexible than fully unitised — glazing can still be adapted on-site.
Less common in the UK market than stick or unitised. Requires careful coordination between factory production and on-site programme.
Semi-unitised systems are typically used in medium-rise office and commercial buildings. They are less prevalent in the UK than in other European markets, but are growing in use as contractors seek to combine the quality benefits of off-site fabrication with the on-site flexibility that many projects require.
Section 06
Structural Glazing and Point-Fixed Systems
Structural glazing and point-fixed (spider glass) systems eliminate or minimise the visible aluminium frame, creating a seamless all-glass facade. Glass panels are fixed directly to the building structure using mechanical point fixings or structural silicone bonding. These systems deliver a high-end, transparent aesthetic and are used in entrance lobbies, atriums, and landmark commercial buildings. They are the most expensive curtain wall option.
Where a conventional curtain wall uses a visible aluminium grid of mullions and transoms to support the glass, structural glazing systems take a different approach. The frame is either hidden behind the glass line or replaced entirely by point fixings — stainless steel spider fittings that attach directly to the glass at each corner.
Spider glass systems create a visually striking, minimal facade with almost no visible framing obstruction. The result is a wall of uninterrupted glass that maximises transparency and light transmission. This is a popular choice for high-end retail, hotel entrances, scenic lift enclosures, and corporate reception areas.
Entrance lobbies, atriums, scenic lifts, high-end retail, landmark commercial buildings requiring maximum transparency
£750–£1,000+/m² — highest cost due to engineering complexity and precision installation
Unmatched visual impact. Minimal sightlines and maximum daylight. Highly bespoke — no two installations are identical.
Requires high precision engineering and specialist installation. Significantly higher cost than framed systems. More complex maintenance.
If your project involves a toughened glass shopfront or a glazed entrance that needs to make a strong visual statement, structural glazing is worth considering. Our team can assess whether it’s the right fit for your building and budget during a free site survey.
Section 07
Spandrel Curtain Wall Panels
Most curtain wall systems on multi-storey buildings include spandrel panels alongside vision glass. Spandrel panels are the opaque sections of the facade, typically positioned at floor and ceiling level to conceal the structural slab, columns, insulation, and mechanical services that sit behind the glazed skin.
Multi-storey commercial buildings where structural elements, services, or insulation need to be concealed behind the facade
Opaque glass (back-painted or ceramic-fritted), aluminium composite panels, stone, or metal cladding inserts
Creates a visually uniform facade from street level. Conceals building services and structure while maintaining the appearance of a fully glazed building.
Spandrel zones are critical for fire compartmentation. UK Building Regulations (Approved Document B) require cavity barriers at spandrel interfaces.
Spandrel panels are rarely a standalone system. They are almost always used in combination with one of the other curtain wall types above, as part of an integrated facade design. If you need commercial glass replacement or are refurbishing an existing curtain wall facade, spandrel panels are often the elements that require the most attention over time.
Section 08
How to Choose the Right Curtain Wall System
The four key factors when choosing a curtain wall system are: building height (which determines whether stick or unitised is more practical), project timeline (unitised installs three times faster), budget (stick is lowest cost, structural glazing is highest), and energy performance requirements (all systems must comply with Approved Document L U-value limits). A free site survey is the most reliable starting point.
There is no single correct answer when specifying a curtain wall system. Every project has a different combination of constraints. The factors below are the ones that most reliably determine which system is appropriate.
Key Decision Factors
- Building height: Stick systems work well up to four or five storeys. Above that, unitised or semi-unitised systems become more practical and cost-effective overall due to reduced site labour and faster programme.
- Site access: Restricted sites — basement-level loading, narrow streets, busy urban locations — favour unitised systems where crane lifts can be planned and panels arrived pre-glazed.
- Project timeline: If your programme is tight, unitised systems install in roughly one third of the time of an equivalent stick system. That difference can be decisive on a commercial development.
- Budget: Stick systems carry the lowest upfront material cost (from £250/m²). Structural glazing is the most expensive (£750–£1,000+/m²). Unitised systems cost more upfront but often reduce overall project cost through labour savings.
- Energy performance: All curtain wall systems installed in the UK must comply with Approved Document L U-value requirements. Thermally broken aluminium frames and double or triple-glazed units with Low-E coatings are standard for compliance. The forthcoming Future Buildings Standard (expected 2027) will tighten these requirements further.
- Fire safety: Approved Document B requires fire-stopping measures, cavity barriers, and compartmentation at curtain wall interfaces with floor slabs. Spandrel zones are a critical area of compliance for multi-storey buildings.
- Conservation areas and listed buildings: Local planning authorities may impose restrictions on materials, finishes, and glazing types. Always confirm consent requirements before specification.
Our guide on how to choose an energy-efficient curtain wall system covers the thermal performance side of this decision in more detail.
For businesses comparing curtain walling with other facade options, it is also worth understanding the difference between curtain walling and aluminium shopfront installation. Shopfronts are designed for ground-level commercial entrances; curtain walling covers multi-storey facade systems. Both use aluminium and glass, but the engineering, fixing, and compliance requirements are quite different.
At a Glance
Curtain Wall System Comparison
| System Type | Assembly | Cost Range | Best For | Installation Speed |
|---|---|---|---|---|
| Stick | On-site | £250–£700/m² | Low-to-mid-rise | Slower |
| Unitised | Factory + crane | £500–£1,000+/m² | High-rise, fast programmes | 3× faster than stick |
| Semi-Unitised | Factory frames, site glazing | £350–£750/m² | Medium-rise, flexible design | Moderate |
| Structural Glazing | Point-fixed on-site | £750–£1,000+/m² | Lobbies, atriums, landmark buildings | Slower, high precision |
| Spandrel | Combined with above | Varies by system | Multi-storey, concealing structure | Per parent system |
Conclusion
The Right System Starts with the Right Survey
Curtain wall systems range from straightforward stick installations on a two-storey retail unit to highly engineered point-fixed glass facades on landmark commercial buildings. The five types covered in this guide each serve a different set of project requirements. None is universally better than the others.
What matters is matching the system to your building, your programme, your budget, and your compliance obligations. Getting that match right at the start of a project saves time, money, and rework later.
At MK Shopfront & Shutters, our engineers survey your premises, assess your requirements, and recommend the most suitable curtain wall system for your project. We handle the full installation process, from initial survey through to completion, with transparent pricing and no hidden costs.
FAQ
Frequently Asked Questions
