Thermally Broken Doesn’t Mean Structurally Broken

What “thermally broken” really means

Say thermally broken lintel (TBL) to a bricklayer on a UK site and you'll often get a raised eyebrow. Broken sounds like something's been cut, weakened, or compromised, but that’s far from the case.

The only thing being broken here is the path that heat takes through the wall. Structurally the lintel performs exactly as it should; the thermal break simply stops heat escaping across the cavity. Far from a weakness, it's deliberate engineering doing precisely what the wall needs.

Why thermally broken lintels are ideal for modern builds

With increasing pressure from the UK Building Regulations to significantly lower carbon emissions in homes, the industry needs to consider a fabric-first approach. The Future Homes Standard requires new builds to produce 75% fewer carbon emissions than a 2013 equivalent. Meeting that target requires everyone to focus on fabric performance from the ground up.

That’s where thermally broken lintels fit in. Every door and window opening is a potential weak point in the building envelope, and a TBL reduces the impact pf those weak points. As a result, it directly contributes to a fabric-first approach, making compliance easier.

How a traditional lintel loses heat

A standard steel lintel consists of a single piece of steel, with an insulated core that spans the cavity. Structurally, it’s excellent. Thermally, it’s a problem.The steel creates a continuous cold bridge from the outside leaf to the inside leaf, directly above every window and door opening. Multiply that across a whole house and you get:

• Significant heat loss
• Higher energy bills
• Increased condensation risk*
• Potential mould at openings*
   

This is exactly the issue a thermally broken lintel is designed to eliminate.

*if installed incorrectly.

How a thermally broken lintel works

Catnic’s TBL range compromises of two folded steel sections bonded to a high strength, thermally efficient structural core. It’s the only steel lintel on the market with:

• No connecting brackets
• No steel crossing the cavity
• No thermal bridge at all

The “break” is in the core, that core:

• Stops heat transfer across the cavity
• Reduces heat flow from the lintel head junction by up to 96%

Catnic’s thermally broken lintels support customers to build warmer, more energy‑efficient homes with less effort. Around 30% of a home’s heat loss happens at window and door openings, and our TBL range is designed to virtually eliminate that thermal‑bridging heat loss. 

The result is a better‑insulated, more airtight building fabric that makes meeting modern regulations far easier, without adding complexity to construction methods on site. 

Our TBL range achieves psi values of 0.02–0.05 W/mK (vs 0.06–0.09 W/mK for standard cavity wall lintels where steel bridges the whole cavity)
In other words: stronger thermally, equally strong structurally.