New technologies for basements made of timber

Timbase builds basements and lower levels using timber construction methods, as well as solid wooden floor slabs. The design is tailored to each specific project’s structural, building physics, and construction requirements. Depending on the situation, various designs are possible, ranging from a single basement level to a combination with existing structures. Additions and extensions can also be built using timber construction.

As a general contractor, we handle the entire planning and construction process, from the foundation to the ground-floor ceiling. The timber builder then takes over to construct the upper floors of your project. The advantage lies in the seamless transition using wood as the material, which greatly simplifies the erection process as well as connections and transitions.

The wooden basement consists of a floor slab and exterior walls constructed of solid wood using cross-laminated timber. These structural elements transfer the vertical loads from the upper floors, as well as the horizontal loads from earth pressure, into the ground. TS3 technology ensures that the floor slab and walls act as a single, rigid unit.

The TS3 joints connect the individual cross-laminated timber panels to one another, forming a three-dimensional “monocoque” made of wood. This is made possible by “Timber Structures 3.0” technology, or TS3 for short. This is a process that allows for the creation of large wooden surfaces. To achieve this, the end faces of the panels are pretreated at the cross-laminated timber plant. On the construction site, the panels are then cast with a resin without applying pressure, thereby forming a rigid connection. This construction method is used for the entire basement. This creates the floor slab, the walls, and the ceiling above the basement, which serves as a load-distribution slab for the building.

Compared to concrete, wood is lightweight. The structural stability of the building was confirmed through special friction tests in the laboratory and measurements taken during the pilot project. Displacement caused by earth pressure can be reliably ruled out during the planning phase using newly determined friction coefficients.

Thermal insulation begins in the basement. Highly insulated wall and floor structures allow for very good U-values to be achieved. Depending on the requirements and construction, this also makes it possible to develop solutions that meet the high energy standards of Minergie or Passive House .

This approach considers not just individual building components, but the entire building physics system: heat, moisture, airtightness, and thermal bridges are all taken into account together from the very beginning. This allows the basement to be optimally integrated into the building’s thermal envelope.

Technical article in English

Using building physics models, the short-term drying behavior was confirmed, and a long-term (> 50 years) forecast was developed. A comparison with the criteria of the WTA 6-8-2016 guideline and DIN 4108 (2014) shows no risks associated with the wood. The standard, integrated, area-wide monitoring system uses modern technologies to ensure quality and provide assurance for the building owner.

Built Quickly

Why not take advantage of the major benefit of wood construction—the fast and dry construction process—in the basement as well? Wooden basements are built significantly faster than conventional concrete basements. A comparison from the project in Thun shows that a basement for a six-unit apartment building was completed in just six days. By comparison, a basement built using solid-construction methods would take about 45 days, not including the curing time for the concrete. Construction of the residential building can begin immediately after the wooden basement is completed—without any delays and with clear advantages in terms of assembly.

Efficiency and Cost Optimization

The wooden basement also delivers impressive cost savings: Thanks to the fast and dry timber construction method, a high standard of finish is achieved after just a few days. The natural wood surfaces and the finished floor structure further contribute to the cost advantages. In contrast, with concrete construction, a curing and drying period must elapse before work on the floor structure and wall and ceiling finishes can begin. Overall, the construction time is significantly reduced, allowing the building to be occupied sooner.

If we want to achieve climate neutrality by 2050, we must stop building with steel and concrete now and switch to wood construction instead. Anyone who wants to contribute to climate protection builds with wood today. In Thun, home to Switzerland’s first apartment building with a wooden basement, a total of 222 metric tons of CO₂ are stored in the wood used in the building—126 metric tons of which are in the innovative wooden basement. If the basement had been constructed using conventional solid-structure methods, the production of these materials alone would have caused over 367 metric tons of CO₂ emissions. That’s a difference of 493 metric tons of CO₂.