In Nietap, Drenthe, Heijmans is building timber-frame homes with hemp in the walls and roof elements. Even though the construction workers sometimes grumble that they long for concrete. “This is the way forward. There’s no doubt about this material.”
Heijmans goes hemp. One of the Netherlands’ largest construction companies is using it as insulation in the walls and roofs of new homes in Nietap. At the same time, it’s investing in growing and harvesting the plant itself. Local farmers see potential in hemp, and Greeninclusive is turning it into insulation blankets.
“Yeah, you could even sleep under it,” laughs Dienke Slatman of Heijmans. “Hemp has the advantage that it doesn’t itch as much as rock wool. Using the material on the construction site is a bit trickier, though. Rock wool is as soft as butter—you can cut right through it with a knife. Hemp is tough—you have to saw through it.”
Slatman, who started out as a carpenter, has been a developer for years now. She appreciates that her employer gives her the opportunity to “develop super-sustainable homes.” It’s no surprise that she serves as the sustainability ambassador at Heijmans Noord.
Dienke Slatman in conversation with Thomas van Belzen for the Bureau Stoer podcast.
“Why is this so great? Well, I think it’s incredibly important that we take this on as the construction and real estate sectors. The raw materials we’ve been using so far are very harmful to the environment. By working with wood and bio-based insulation materials, you’re simply doing a much better job,” says Slatman in a construction trailer at a project site in Nietap. “This also ensures that future generations will continue to live in a livable country.”
Innovating in a world of stone
She really loves her job, and pushing boundaries is second nature to her. Even if that sometimes happens in fits and starts in a world of stone. “Change is definitely happening, and we’re all very eager to make it happen. Now it’s important that we do it together.”
The project in Nietap features open paving, wadi-style waterways, birdhouses on the for-sale and rental homes, and drainage at ground level.
A total of 35 homes are involved. Two years ago, when the homes went on sale, there were long lines of more than 2,000 interested buyers. But now that it comes down to it, the necessary signatures aren’t coming through.
Grumbling construction workers
“The exact turnkey price is a bit of a letdown,” explains Slatman. “The costs of a super-sustainable home are simply higher than those of traditional construction. Hemp is just expensive. And timber-frame construction is more expensive than concrete construction anyway. Maybe we didn’t explain it well enough. Or maybe we’re just not ready for it yet.”
There’s some grumbling on the construction site every now and then, too. “That could have been done much more simply,” Slatman sometimes hears construction workers mutter. “I would have just built this with other materials. Preferably concrete.”
Using hemp in wooden row houses is no easy feat, according to Slatman. In fact, it’s rarely been done before. “Wood is fire-safe. Hemp in wood works just fine, but as soon as you connect houses together, fire safety becomes an issue. You don’t want a potential fire to spread to another house. Stricter standards apply there. Maybe hemp could have worked, but this application hasn’t been certified yet.” Heijmans brought in consultants. And solved the problem by installing rock wool on the ends of the walls separating the homes.”
This is the route
It’s a moving story. About a builder and developer who feels the need to build differently for the sake of Mother Earth and the environment. And even though it’s more expensive, even though it’s more complicated, even though the construction workers grumble… Heijmans is sticking with wood and hemp: “This is the way forward. There’s no doubt about this material. I hope the entire real estate and construction industry dares to take this leap. If everyone starts building with hemp, it will naturally become cheaper.”
This story is based on the latest episode of the Bureau Stoer podcast. You can listen to it here.
