Wood-aluminum window frames on IJburg

Low maintenance on the outside, warm on the inside

The Netherlands is currently building more apartment buildings than ground-level homes. For the high facade, more and more building owners, designers and builders are discovering the (environmental) advantages of wood-aluminum window frames. Indeed, the high insulation value, the natural wood appearance in the interior, the weather-resistant aluminum and the freedom of maintenance make this type of window frame ideal for high-rise projects.

In 2023, the share of apartments in total housing new construction was still below 50 percent. In 2024 it grew to 55 percent, and market research firm for the construction industry Buildsight in Den Bosch expects it to rise further to 60 percent by 2027. In the high-rise segment, wood-aluminum window frames are increasingly becoming the logical choice. The hybrid window frame combines the advantages of wood (renewable, appearance and insulation - in combination with triple glazing up to U-value 0.64) with the low-maintenance properties of aluminum. The combination of wood with an aluminum exterior profile also fits in well with biobased construction and has favorable effects on the MPG sustainability performance of a building. 

Mooijburg

A low MPG plays an increasing role in high-rise buildings. The three apartment buildings Mooijburg Plein (block 12-06) and Mooijburg Waterzicht (block 10-10) each have fifteen homes. Mooijburg Park (block 07-06) has eighteen residences. They are located on center island IJburg in Amsterdam because of the sustainability goals all three are based on a construction of CLT and wood frame construction. Architect is Natrufied Architecture in Bergen. In Mooijburg Plein and Mooijburg Waterzicht wood-aluminum window frames were chosen in consultation with the residents. Architect/partner Anja Verdonk says: "As a firm, we focus heavily on bio-based construction. Hence the wooden construction and façade finishing. For us, aluminum window frames are actually a no-go for biobased building. We chose wood-aluminum window frames in a warm shade of wood for two apartment buildings together with the residents because of the low maintenance." Mooijburg Park has a façade of scaffoldless hsb façade elements and wooden window frames. 

Natural wood appearance

Mooijburg's total of 189 wooden and 262 wood-aluminum window frames and the hsb elements into which they are factory fitted are from WEBO in Rijssen. This manufacturer supplies its products with the quality mark HOUT100% and is a member of the Dutch Branchevereniging van de Timmerindustrie NBVT. WEBO carried out both the engineering with BIM, production and assembly of Mooijburg for Weever Bouw from Kampen. 

WEBO wood/aluminum specialist Job Huisman says: "Because of the client's sustainability requirements, wood-aluminum window frames have been on the rise for the past three years. The use of domestic pine, larch and spruce, but also oak, is very well possible in combination with an aluminum exterior profile. In principle, the wood does not need to be painted on the inside. Thus, the natural wood appearance is retained. The aluminum exterior profile is also low maintenance: it suffices if the window cleaner also periodically cleans the window frames." 

Matching the CLT construction, architect and residents at Mooijburg chose transparent finished optimized larch. The aluminum on the exterior is finished in Elocal bronze. WEBO delivers the elements just-in-time and fully glazed at the construction site. 

Fireproof

WEBO's fire-resistant wooden and wood-aluminum window frames are CE marked according to EN 16034. Huisman: "Fire resistance and smoke tests at Peutz show that the wood-aluminum structures with surplus value meet the requirements of 30-60 minutes of fire resistance and protect against fire penetration and flashover. For escape routes, the structures provide protection against smoke." 

The wood-aluminum window frames were tested according to the evaluation criteria EW and EI1. In addition, the fire-resistant exterior doors were tested for smoke (SA and S200) and self-closing capability (C) in accordance with European standard EN 1634-1. In order to realize variations on the tested systems in practice, extended application areas (ExAp) with corresponding classifications have also been drawn up in accordance with EN 15269-3. WEBO has a white paper Fire Safety and Frames available for download on its website. 

Like Buildsight, Huisman also expects the wood-aluminum window frame market to continue to grow in the coming years. "The aluminum exterior profile opens up the possibility of using sustainably produced softwood under warranty. Moreover, WEBO now has experience with the application of reclaimed scrap wood in the window frames of a house in Rijssen and a housing project in Silvolde. It doesn't get more bio-based and circular than that."

Wood frames, particularly in the form of wood-aluminum frames, are a suitable choice for high-rise buildings. They offer a combination of durability, insulation, appearance and ease of maintenance and can meet the specific requirements of high-rise buildings, such as fire safety and building physics.