Inside Threadworks: how we delivered a 24-storey aluminium façade

Synopsis

An in-depth look at the technical and practical challenges of delivering a 24-storey aluminium rainscreen façade. Tom Prince, Contracts Director at Caxton Façades, shares lessons on design coordination, panel fabrication, fire safety, compliance, logistics and sequencing, and the considerations that matter when delivering complex high-rise PBSA façades.

Tom Prince, Contracts Director at Caxton Façades, answers some of the key technical questions behind the delivery of the Threadworks façade.

What was Caxton Façades’ scope at Threadworks?

Threadworks is a 24-storey, 548-bed purpose-built student accommodation development in central Leeds. Designed by DMWR Architects and built by Winvic Construction for CASL Lisbon Street, it forms part of the wider Lisbon Street development on the former Leeds International Swimming Pool site.

Our package covered the design and installation of approximately 9,000m² of aluminium rainscreen cladding, principally using BTS Façades’ Vantage® DF system.

The elevations also incorporated cranked and castellated aluminium panels, aluminium soffits and bespoke shell elements, together with open-state and closed-state cavity barriers within the external wall build-up.

The scale was significant, but the real complexity came from combining the architectural geometry, fire performance requirements, programme and logistics on a constrained city-centre site.

The building achieved BREEAM Excellent and welcomed its first students for the 2025/26 academic year.

What made the Threadworks façade technically demanding?

There were three main considerations: the architectural intent, the fire performance requirements and the geometry of the panels.

DMWR hadn’t designed a flat-faced tower. The elevations use cranked panels, which fold along defined angles to introduce depth and shadow, and castellated panels with stepped profiles that create rhythm and texture across the façade.

Those details have to align consistently across very large areas. If you’re slightly out at one level, that discrepancy can become much more apparent as the elevation progresses. We therefore had to pay very close attention to panel dimensions, carrier rails, interfaces and tolerances.

Fire performance was equally important. Threadworks is a higher-risk building, so there needed to be a high level of control and traceability around the external wall build-up.

It isn’t enough to look at each product in isolation. You have to consider how the insulation, cavity barriers, substructure, panels, fixings and interfaces come together as a complete façade, and make sure what is installed reflects the approved design.

How are cranked aluminium panels manufactured, and why does accuracy matter?

Cranked panels are aluminium rainscreen panels formed along one or more predetermined fold lines during fabrication. At Threadworks, they’re used alongside standard flat panels to create the geometry required by the architectural design.

The key point is that the geometry is established during manufacture. You can’t get a cranked panel to site and make a significant adjustment to it because something doesn’t line up.

The crank angle, panel dimensions, fixing positions and relationship with adjoining panels all need to be resolved before fabrication. That’s why the shop drawing and design coordination stages are so important.

An error doesn’t necessarily affect just one panel. It can change joint widths, alignment with neighbouring panels or the continuity of an architectural feature further along the elevation.

Our aim is therefore to resolve as much as possible through coordinated design and fabrication information before material reaches site. The more you resolve at that stage, the less risk you transfer to installation.

How did you work with BTS Façades?

The principal cladding solution was BTS Façades’ Vantage® DF system, a drained and ventilated aluminium rainscreen system using a precision-engineered carrier rail and discreet, colour-matched fixings.

It’s worth explaining the difference between discreet fix and secret fix, because the terms are sometimes used interchangeably.

With a secret-fix system, the primary panel fixings are concealed behind the panel face. A discreet-fix system uses small, typically colour-matched fasteners. They’re technically visible, but their visual impact is very limited when you view the completed elevation from a normal distance.

Our relationship with BTS covered much more than supplying the panels. We worked together through design development, shop drawings, fabrication and sequencing.

That was particularly important because Threadworks combines the standard system with project-specific elements. We needed to establish what could be achieved within the standard system and where bespoke components were required to deliver DMWR’s architectural intent.

The factory programme also had to work with our installation programme. On a constrained site, you don’t want large quantities of panels arriving before you can use them, so manufacturing, delivery and installation have to be considered as one sequence.

How were cavity barriers managed within the façade?

Cavity barriers are a critical part of the external wall fire strategy, particularly because they become concealed once the façade is complete.

Threadworks incorporates both closed-state and open-state cavity barriers at locations defined by the approved façade design and fire strategy.

Closed-state barriers provide fire resistance by closing the cavity at defined locations. Open-state barriers allow the ventilation required by the rainscreen cavity during normal use but incorporate intumescent material designed to expand and close the cavity when exposed to fire.

The important point is that specifying the correct product is only part of the process. It also has to be installed in the correct position, against the appropriate substrate, using the correct fixing method and with the required continuity.

Caxton Façades is a FIRAS-accredited installer of façade fire-stopping products, so we work to a defined installation and inspection process. At Threadworks, that included trained operatives, approved installation information, inspection and test plans, photographic records and digital documentation.

Traceability is particularly important because once the rainscreen panels have been installed, you can’t simply look at the finished elevation and verify everything behind it.

You need a record that demonstrates what was installed, where it was installed and how it was checked.

How do you install aluminium cladding on a 24-storey building?

Technically, the sequence is relatively straightforward: establish the supporting construction and carrier system, install the insulation and cavity barriers, and then install the rainscreen panels in the required sequence.

In practice, on a building like Threadworks, a significant part of the challenge is logistics and sequencing.

The site is in central Leeds, close to Leeds railway station, with limited storage and laydown space. We couldn’t simply bring large quantities of panels onto site and store them until they were needed.

Deliveries therefore had to be closely aligned with installation. Too early and you’ve created a storage and handling problem; too late and you risk interrupting the programme.

We were also working around multiple other trades. The façade interfaces with windows, the supporting wall construction, fire-stopping and numerous perimeter details. If preceding work isn’t complete, inspected and within tolerance, it can affect the next stage.

Then there is the height itself. At around 75 metres, access systems, lifting, material distribution and weather all become more significant considerations.

For me, that’s one of the main lessons from high-rise façade work: logistics isn’t separate from the technical solution. It’s part of it.

How did you coordinate with Winvic and DMWR throughout delivery?

Early engagement made a significant difference.

We were involved during the earlier stages of construction, which gave us the opportunity to work through façade details and interfaces before installation. That included the relationship between the rainscreen, openings, supporting construction and fire-stopping requirements, as well as the project-specific aluminium details.

Once we were on site, that coordination continued through design reviews, technical queries, programme meetings and day-to-day discussions with Winvic and the other subcontractors.

PBSA also has a very clear programme driver: students need to be able to move in for the new academic year. That puts additional emphasis on identifying dependencies early rather than discovering them during installation.

The façade works were completed within the agreed programme and the building was ready for its planned student intake.

What can other high-rise PBSA projects learn from Threadworks?

There are four things I would take from the project.

Engage the façade specialist early. A lot of façade risk can be designed out before anyone starts installing panels. Panel optimisation, tolerances, interfaces, access, fire-stopping and manufacturing constraints all benefit from early specialist input.

Treat fabrication as part of the construction programme. With prefabricated aluminium panels, shop drawing approval, procurement, fabrication, quality checks, delivery and installation form one continuous process. A delay at one stage quickly affects the next.

Build the compliance record as you go. Many safety-critical elements become concealed as the façade progresses. Inspection records, photographs and supporting documentation need to be captured at the point of installation rather than reconstructed later.

Consider logistics as early as design. On a high-rise city-centre project, delivery sequence, lifting, access, storage and interfaces with other trades can have just as much impact on programme as the installation of the cladding itself.

Threadworks reinforced something we see across complex façade projects: the finished elevation may look relatively simple, but achieving that result depends on a long chain of coordinated decisions.

Design, fabrication, fire performance, logistics, installation, inspection and record keeping all affect one another. At 24 storeys, small issues can quickly become significant ones.

The more of those issues you resolve before materials arrive on site, the more controlled the installation becomes.