Madrid-based Strong by Form has raised €5.8 million to build a wooden floor slab it says is as strong as steel and concrete at 80 per cent less weight, with the company revealing the first tranche of a 10 million euro Series A on Wednesday. The round is led by Boisei Investments, a US venture investor, and is joined by CMPC, the Chilean giant that led the company’s US $5.2 million seed round in 2023.
“Our mission has always been to prove that wood can compete with concrete and steel on their own terms,” Andrés Mitnik said, with Strong by Form’s chief executive and co-founder wanting wood chosen “not as the sustainable choice, but as the better one”.
The slab, known as Woodflow-core, spans 10 metres at 40 centimetres deep, with the wood fibre placed only where the floor carries load. The reference slab measures 10 metres by 2.5 metres and is designed for an office floor load of 5.5 kilonewtons per square metre.
Those numbers come from bending tests on full-size slabs and computer modelling by an engineering firm the company does not name. Strong by Form rates the slab at technology readiness level six, three steps short of a proven product.
The 2023 pitch was concrete’s strength at one-tenth of the weight
When Strong by Form raised its seed round in December 2023, it was pitching the strength of concrete at one-tenth of the weight. Today, the claim is that the slab weighs 80 per cent less, and the company adds that the slab uses 75 per cent fewer trees than other engineered wood products.
Strong by Form says the concrete slab market is a $120 billion global market, and that cross-laminated timber has captured less than $1.5 billion of it. Rather than compete with mass timber manufacturers, it wants to partner with them, offering a market it says is 80 times larger than theirs and margins up to 50 per cent higher.
The finished floor is built by a CLT manufacturer combining Woodflow with its own product, Mitnik said in an interview published on Wednesday. It looks like a normal mass timber slab and takes the same screws and connections.
The company does not print wood, he said, because “the best 3D printer for wood is a tree”. Instead, it flakes the tree and reassembles the flakes, allowing it to use low-grade wood with no commercial value.
“Strong by Form is exactly the kind of company we back: deep science applied to one of the largest decarbonization challenges on the planet,” George Perry, who founded Boisei Labs, the Pennsylvania venture studio behind the lead investor, said. The Penn State professor of anthropology and biology is backing “a business model that wins on economics alone, not on goodwill”.
Five of the seed investors are back: CMPC, VX Ventures, Savia Ventures, Teampact Ventures, and FINSA, the Spanish panel maker. Ternel, Axel Carbon, and a group of unnamed family offices join the round, while Climate Insiders, Ciri Ventures, MAIF Avenir, Core Angels, and Symbia VC from the seed round are not named.
Strong by Form names VINCI, the French construction group, and Austrian timber group Pfeifer among its strategic investors and partners. The first close was reported at $6.6 million in August, when the company gave its target as $10 million to $15 million.
“We have supported Strong by Form since its early stages because of its unique approach to engineering wood inspired by nature,” Bernardita Araya, CMPC Ventures fund manager, said. She called the round the foundation for “the next phase of industrialization and market adoption”.
Woodflow-skin, the wave-patterned cladding the company sold first, is already on the market in the United States, the United Kingdom, and Europe. It is fitted in trains, with NS and Deutsche Bahn among the company’s rail partners, and Strong by Form has worked with BMW on car parts since before the seed round.
