A collaboration between WNL and SAB-profiel results in a unique roof panel for the greenhouse construction sector

Sandwich panels are a familiar material for roofs of greenhouses and industrial spaces. These panels are durable, low-maintenance, and contribute to energy conservation. To make the panel deck waterproof, the panel joints are sealed with adhesive, which comes with its fair share of disadvantages. Supplier WNL Horti Insulation and manufacturer SAB-profiel joined forces for a revolutionary solution: the WNL Easyjoint. “This is a game-changer that demonstrates how innovation can lead to real savings for everyone in horticulture,” says Gert Hollaar from WNL.

Greenhouse builders are accustomed to using sealant as part of the process when assembling sandwich panels on a greenhouse roof. Well-applied sealant can maintain water tightness for a while. “Sealant is a nice solution, but one thing is certain: over time, it wears out and you’ll start experiencing leaks,” says Gert-Jan Evers, Sales Manager at SAB-profiel, which has been producing sandwich panels for WNL Horti Insulation for years. Gert Hollaar adds, “Because traditional roof panels don’t fit into the aluminum profiles of the greenhouse systems, a wall panel is used instead. That works, as long as the connection between two panels is good. You have to be willing to spend money on good sealant and you’re dependent on conditions like the weather during construction. In the past, too much went wrong. The person doing the sealing is the most important link. If they don’t apply the sealant properly, you turn a solution into a problem. With new construction, it often goes well right away. But if you’re sealing afterwards, you’re more focused on improvising.”

Joint development

The assembly also takes a lot of time. All in all, it’s a costly process for greenhouse builders. Gert-Jan: ‘Gert came to us with ideas for change. We went looking for a solution where you no longer need to seal. It has been a joint development. WNL came with the requirements package, we looked at the product. We brought in our technicians: what can be produced, what can’t? You don’t want disruptions in production, they only cost money. And a very nice panel came out of that.’

A real roof panel developed

The solution ultimately turns out to be a sealing strip. Gert: ‘About five years ago, I already created a kind of channel at the bottom of the panel with SAB-profiel. If a drop were to fall, it would land in the channel and then in the greenhouse gutter. That was already a huge improvement. But ideally, you want to stop the water on the outside of the greenhouse. We’ve now addressed that. The biggest gain is that we no longer use a wall panel as a roof panel. With a seal like this, it has become a real roof panel, specifically produced for this application.

Rubber profile

Gert-Jan: ‘We apply it in the factory. A strip ensures a perfect seal. The strip is UV-resistant and can withstand very high and very low temperatures. Dutch greenhouse builders erect greenhouses worldwide in places where it can be 40 degrees above zero and 25 below zero. WNL has a patent on this system, and we expect great interest.’ The sandwich panels with Easyjoint are therefore exclusively available from WNL Horti Insulation for this reason.

“The first 55 thousand meters are already in place.”

WNL didn’t have to wait long for interest. “The first 55 thousand meters with the new roof panels are already installed in Arizona, Virginia, Portugal, England, the Netherlands, Japan, and Algeria. Greenhouse builders are discovering it now. First, I had to ask: do you want the WNL Easyjoint? Now they immediately say: just give me that, and I’ll eliminate that annoying sealing.”

Gert-Jan, on behalf of SAB-profiel, looks back on a successful co-creation. “There was quite a bit of time involved in the whole development. After a few pilots, we want to go full throttle. WNL Horti Insulation and SAB-profiel have been getting along very well for years. It’s a collaboration based on trust.” The trust that even for a long-standing problem, there is an innovative solution…