Wood floor pro Filip Redant installs a typical subfloor in Belgium.

Waffles aren’t the only special thing in Belgium—wood floor subfloors are also on the list and are an art in themselves.

Instead of plywood, Belgian wood flooring pros install 5-inch-by-5-inch squares that look like standard-pattern parquet over concrete, says Filip Redant, owner of Mechelen, Belgium-based Atelier Passe Partout. The solid oak used is from an inferior grade of wood (“third choice” in Belgium), and is 8 mm thick compared with the typical wood flooring thickness of 9 mm in Belgium, Redant says.

The oak blocks are stronger than plywood and they’re also easier to install, according to Redant. “Plywood is not always flat, which results in possible hollow zones between the concrete and the plywood,” he says. The smaller oak squares ensure 100% contact with the concrete.

When installing the mosaic subfloor, Redant turns each square 90 degrees so the length of the boards is next to the ends of surrounding boards. Because wood expansion usually occurs only across the widths of boards, the 90-degree turning technique keeps any expanding boards from bumping up against one another.

Once the mosaic is installed and the glue is dry, the subfloor is sanded. “The subfloor is always sanded in order to have a totally smooth surface,” Redant says. From there, Belgian wood flooring pros begin installing their hardwood floors. The oak mosaic subfloor technique is also used across Europe, according to Redant.

Redant used the subfloor technique in a recreation of an 1830s palace parquet at the famed M-Museum in Leuven, Belgium [see more information about that project in the June/July 2019 issue of Wood Floor Business]. The only difference in that unique project was the architect required the oak subfloor to be from the highest grade and the grain facing the same direction. “In my opinion, this was not better than the normally used mosaic subfloor,” Redant says. See that stunning project here.