Recessed windows: combining high performance with Northern European aesthetics

In the current era of the construction industry in New Zealand, thermal efficiency and weathertightness are one of the most significant and often discussed issues. With some of the H1 changes to the Building Code coming into effect this year, and more to come throughout 2023, it’s imperative that the industry gets on board with solutions that prioritise these two crucial elements.

Windows are one of the most significant vectors through which heat can escape a home, so naturally they are one of the primary considerations when insulating. And when it comes to windows, New Zealanders have a love affair with aluminium joinery: it is, by far, the most common joinery material for windows. But in the wake of the Building Code changes, aluminium joinery will need to up its thermal efficiency game in order to comply.

There are several ways to do this. To improve thermal efficiency, aluminium can be thermally broken – but this doesn’t address the issue of weathertightness. Recessed window flashing systems, on the other hand, can improve both insulation and weathertightness performance simultaneously.

Rosenfeld Kidson, a New Zealand owned and operated company that stocks a huge range of over 50 species of specialist timbers, has an especially dominant expertise in this field: its INTERSET recessed window flashing system for both vertical and horizontal shiplap has stood out in the industry for many years.

Ray Hutton, the company’s National Marketing and Specification Manager, says the act of setting the joinery back to the frameline – or ‘recessing’ the joinery – creates several benefits for the performance and aesthetics of windows.

“The INTERSET creates a 65mm deep recess to the head, sill and jamb line,” says Ray. “The system consists of a set of aluminium flashings and thermoplastic stop-ends that interlink to form a ‘picture-framed’ window recess – both of which work to improve the weathertightness and thermal performance of the window itself.”

The INTERSET system sets itself apart by virtue of its ability to be installed on not just vertical but modern horizontal rusticated boards. In fact, it was developed eight years ago with vertical weatherboards in mind – used especially in conjunction with western red cedar, truwood and larch timbers.

“As far as I know, there is no other timber recessed window on the market in New Zealand that is designed specifically for vertical weatherboards – so it is quite unique,” says Ray. “I think it’s this uniqueness that has played a big part in INTERSET becoming so well-established in the marketplace.”

But, Ray goes on to say, the performance and unique installation potential aren’t the only benefits of the system. In addition to its ability to be installed on a wider variety of weatherboards, the installation of the system itself is also very straightforward.

“We have a really clever 3D modelling system called WorkingSpec, which builders can use in conjunction with INTERSET,” says Ray. “The builder just needs to download the app, and simply tag the QR codes – which brings up an extremely targeted 3D imaging interface which is highly interactable. It can be rotated and expanded, and you can track back and break down the build process to the key phases of installation.”

But even with the myriad of physical benefits, Ray says the system has endured throughout the years primarily because of its aesthetic appeal. Not just because it’s well-suited to vertical shiplap – a trendy weatherboard format that continues to rise in popularity around Aotearoa – but also on its own visual merits.

“Its main aesthetic benefit is that it adds relief to the façade,” says Ray. “Often, face-mounted joinery can look quite boxy – it can look like it’s ‘pushing out’ the cladding. Having a recessed option creates shadow lines, adds depth – both literally and figuratively – and it lends the façade a higher-end Northern European design aesthetic.

“Clients want to have all of these elements in their windows – weathertightness, thermal efficiency, ease of installation and aesthetic appeal,” says Ray. “And with INTERSET, I think we deliver this really well.”

Learn more about Rosenfeld Kidson and its recessed window flashing system.