Deep-seated knowledge paves the way to the future

When we look at the patriotic door industry, we can safely say that there is expertise in our country from the very beginning. One of the companies it is impossible to imagine the industry without is KEGRO doors from Groesbeek. Jan Kersten has been serving the market since 1974 and is still at the top of the league with great developments.

Detail cross-sectional hinge angle outside.

We speak with him at his office in Groesbeek, about the evolution in the door industry, new techniques that could well become normative and the urge to keep innovating, towards a sustainable society.

The plastic window frame industry demands wood
"The market for plastic and aluminum window frames is picking up tremendously. Fullaccording to our own 'industry barometer', this market has grown by 40%," says Kersten. "In terms of design, the wishes are also increasing, architects are therefore often looking at wooden exterior doors. However, plastic window frames and wooden doors have traditionally not been a good marriage. Solutions in plastic are regularly rejected by the architect, finding an aesthetically pleasing plastic door at a good price is a problem. Often people then opt for an all-wood frame with wood door. On the threshold of 2020, the desire is growing to find a good solution to combine wooden doors with plastic frames. We have responded to that demand and we can proudly report that we have developed a beautiful solution."

Detail hinge corner outside.

Combining a real wood door with a plastic or aluminum frame
"With our new concept - as far as I know the only one in the world - from now on you can combine a real wooden door with a plastic or aluminum frame, without any adverse effects. The door is constructed from a wooden frame complete with steel-reinforced cold-bridge-free stabilization. The stable wooden panel also contributes to keeping the door stable. The outer plate is made of HDF, under which a layer of aluminum sheet material is applied, this keeps the door straight and forms a barrier against moisture," Kersten explains.

"The door then goes into a press, after which it is injected with PU foam for insulation and rigidity. We are talking about a pressure-resistant foam of 85 to 95 kg per m³. Then we calibrate the door and when it is completely flat, we apply the exterior panel, made of Tricoya wood. Last is the turn of the design, in the form of milling and we can apply the decorative treatments. We can go a long way this way, with the design ideas that architects have."

Customized for every profile house
Kersten describes how finally the door is milled over and the seals are fitted. "We adjust the thickness of the door to fit the plastic frame of the respective profile house. Currently, 80 mm is the largest production thickness for overlay doors demanded by the market. Should this change, we can effortlessly produce doors for deeper profile rebates," he promises.

Detail cross-sectional corner closing side.

"The hinges are invisibly pre-assembled. Another advantage over plastic doors, where there are unsightly hinge elements on the door. Our hinges are 3D adjustable, achieving perfect closure. We therefore have a certificate for passive house doors with this hinge system. The doors can be fitted with triple glazing, whatever one desires. The coating comes in any color, however, those who go for the ultimate wood look can choose oak and mahogany as standard, or walnut and Oregon pine."

Good cooperation for a top result
Such a door also requires the best possible sill. KEGRO did not rush into its choice: a partnership with Venster Techniek from Zelhem is a fact. Kersten: "Venster Techniek provides the sill and the seals, so we can guarantee that the wooden door also closes perfectly in a plastic or aluminum frame. Together with our 3D hinges we can talk about a special door, the whole set is guaranteed airtight, with a water tightness of 600 Pa (values for coastal application, at 100 meters height).

In conclusion, Kersten says, "In doing so, we have solved a problem that had existed for a long time, putting our decades of expertise to good use." 

Text: Jan Mol   |  Image: KEGRO
Featured image: With Jan Kersten, the industry has been able to get through the same door since 1974.