Ultra-thin triple glazing is moving from niche to mainstream, driven by tougher U-value targets and carbon reduction goals. Thermoseal Group is ready to meet this demand with the expertise, flexibility and responsive spacer technology.

Traditionally, triple glazing in the UK has been based on 28mm units, constructed using 3 x 4mm glass layers, or 2 x 4mm and a 6.8mm laminate. Now, slimmer window systems are creating demand for ultra-thin profiles, particularly in applications where weight, aesthetics, or retrofitting are a concern.

For these slim units, construction options include 2 x 4mm panes, with a middle pane ranging between 0.5-2mm, or 1 x 4mm pane, a middle pane of 0.5–2mm, and a layer of 6.8mm laminate. This results in a demand for air spaces of 6mm, 8mm, or 10mm.

In tandem, European-style frames are creating demand for thicker triple glazed IGUs up to 52mm. This means manufacturers need supply partners capable of producing high volumes across the full spectrum of sizes – and Thermoseal has put the capacity in place to do exactly that.

“Ultra-thin triple glazing is no longer a concept; it’s happening now,” explained Mark Hickox, sales director at Thermoseal Group. “We’re seeing more customers request slimmer units that can deliver the energy performance of triple glazing without the added bulk.

“At the same time, demand for thicker IGUs is growing as European profiles gain traction. Our job is to give manufacturers the freedom to produce any unit they need, knowing they can get the right warm edge spacer every time.”

Thermoseal has invested significantly to keep pace with this demand. Operating five spacer bar lines, the company has implemented a campaign-based production model that delivers both consistency and agility.

Core sizes like 20mm remain available in volume, but slimmer sizes such as 14mm, 16mm and 18mm can be introduced into production runs quickly and efficiently to meet rising demand for ultra-thin triple glazing.

Larger sizes such as 22mm and 24mm are also seamlessly integrated, ensuring manufacturers have access to the full range of options.

“We’ve engineered our production to be as responsive as the market requires,” continues Mark. “Whether customers are manufacturing 14mm ultra-thin units for lightweight applications or 24mm for larger systems, we can adapt instantly without compromising stock levels or lead times. That flexibility is crucial as demand patterns change.”

Alongside its manufacturing strength, Thermoseal’s product performance remains a key differentiator. Thermobar, its rigid tube spacer, and Thermoflex, its flexible silicone foam option, are both designed to optimise thermal performance across slim and thick IGUs alike.

And through Fenzi Group’s acquisition of Thermoseal Group last year, its customers also have access to Fenzi’s Thermoplastic spacers (TPS) – giving customers a variety of spacer options to suit their production and project requirements.

“In ultra-thin triple glazing, performance cannot be compromised,” adds Mark. “The slimmer the unit, the tighter the margin for error in achieving U-values. That’s where choosing proven warm edge products makes all the difference. With our warm edge spacers, our customers know they’re working with the highest-performing components on the market.”

More than three quarters of Thermoseal’s products are manufactured in-house at its UK sites, underpinned by extensive testing in one of the industry’s most advanced EN1279 labs. This in-house control not only guarantees quality and compliance but also allows for rapid R&D to respond to emerging trends such as ultra-thin triple glazing.

“Being in control of our own manufacturing and testing means we can move fast,” says Mark. “We can take a customer request, validate it in our lab, and adjust our tooling or production almost immediately. That kind of agility is exactly what the market needs as ultra-thin triple glazing grows.”

As the industry prepares for the Future Homes Standard, Thermoseal Group has positioned itself as the go-to partner for spacer technology across all IGU formats. From ultra-thin triple glazing to the thickest European-style units, the company’s investment in capacity, innovation and performance is ensuring its customers are equipped for the future.

“We’re not just reacting to this shift,” concludes Mark. “We’ve anticipated it, invested in it, and built the capacity to support it. Whether it’s 14mm or 24mm, ultra-thin or oversized, Thermoseal can deliver the warm edge solution our customers need to stay ahead.”