School Richterswil, Field 1+2, Richterswil

The project
The existing school building was extended by 2 floors. In order to keep the weight of the addition as low as possible, early planning was done with a timber structure. Timbatec proposed the construction method with a TS3 slab so that the loads could be transferred directly to the load-bearing columns and walls below.
The cross-laminated timber panels were pre-treated in the factory and provided with sealing and segmental bands (white and black bands on the face). After positioning, they were joined together by joint grouting. Finally, on the underside of the ceiling, the joint is hardly visible. Beams are no longer necessary.

The construction
Since the top existing concrete floor was not strong enough to support the required 300 kg/m² a solid wood floor, cast with TS3, had to be installed on top of the existing concrete floor. Thus, all new loads are distributed directly to the load-bearing elements on the lower floors and the concrete floor is no longer loaded. A second challenge was that the entire construction work took place during ongoing school operations. Thanks to the prefabrication of the timber construction, the shell of the extension could be erected in 2 weeks during the summer vacations.

The challenge
The building was erected with solid wood ceilings (CLT TS3) on exterior walls in timber frame construction and interior walls in solid wood (CLT).