Fashionably late

With u-values as low as 1.2W/m²K double-glazed, Mark Haley, argues Kömmerling’s new flush casement may have been later to the party, but it’s worth taking note of. We report.

It’s incredible how much things can change in only a decade – and if a single system has defined the last 10-years in window and door manufacture, it has to be the Residence Collection and R9.

PVC-U casements simply didn’t exist before R9’s launch in 2011, revolutionising PVC-U window manufacture – and the industry hasn’t looked back.

Every major PVC-U systems company now has a flush casement offer. With the launch of its new 70mm flush casement at the end of last year, Kömmerling may be late to the party, but Mark Haley, managing director, HWL, argues it’s been worth waiting for.

“It’s a very considered system,” he says. “Kömmerling haven’t exactly been quick off the mark, they’ve launched later than other systems, but that’s allowed them to understand what works, what doesn’t and what the market needs.

“It’s an exceptionally strong mid-to premium market offer,” he adds.

This is high praise indeed from a company which has pioneered the manufacture of PVC-U flush casement products and which took the bold step to singularly specialise in them, ditching standard product, at the end of last year.

This includes HWL’s pioneering development of a non-glass-bonded 90° jointed R9 window in 2017, replicating a traditional 90° mechanical joint on both sides of a welded sash using Timberweld.

“The work we put in to develop R9 as a non-glass bonded product and to deliver a 90° traditional timber-type joint using Timberweld – well, it puts us in a unique position now in our manufacture of the Kömmerling flush casement,” explains Mark.

“You can’t just start doing and get results, we’ve evolved what we do over the last five-years, what that means is that we’re in a unique position to offer a 90° Timberwelded Kömmerling flush casement – and we’re set up to do so at volume, with a dedicated line.”

Supplied by HWL in a Timberwelded 90° joint – as standard – the Kömmerling Flush is an ultra-energy- efficient six-chamber system. This means that it comfortably achieves a u-value of 1.2 W/m²K – without having to go to a triple-glazed unit.

Mark argues that’s important because it means that the Kömmerling flush meets new requirements under Part L for newbuild, without needing far more expensive triple-glazed units.

“Part L from June delivers a massive step-change in requirements for thermal performance. Home improvement at 1.4 W/m²K, is achievable for most systems but 1.2 W/m²K for newbuild? That is tight for a lot of systems, even PVC-U ones, without going to a triple-glazed, which no one wants because of the weight and the cost.

Mark continues: “We associate flush casements with heritage and replacement markets but a lot of flush products go into new build because housebuilders have recognised that people like them and they help to sell houses.

“That means that from June this year you need to be able to hit that 1.2 W/m²K u-value. We and our customers can, without going to a triple glazed IGU and the massive complexity that goes with that.”

As well as delivering an advanced level of thermal performance and elegant flush finish, the Kömmerling flush casement uses a flush finish gasket and discrete weather sealing. A special sash locator system also guarantees that the sash always returns to a central position in the frame, guaranteeing symmetry of sightlines.

“The sash locator system is another neat innovation from Kömmerling,” continues Mark. “Again, I’ve no doubt that it’s the product of coming to flush products later.

“They’ve looked at other mid-market systems and recognised that the sash and frame don’t always line-up symmetrically and developed a solution which means that in the Kömmerling flush they do.

“The weather seal also sits back a little from the sash so it’s not so prominent when its closed – they’re little innovations but they deliver a far stronger aesthetic.

“In a product that is sold on the strength of its appearance, that’s important, creating opportunities to sell against those systems that don’t, even if they got to market first.”