Zwolle –  Three-story building with CLT structure


Zwolle, Netherlands

CLT/Timber Structure

This three-story building has CLT structure with total area of 789 m2. Building is placed between several existing buildings and have entrances from two streets. 

Vertical elements of structure are CLT walls and GL and steel columns. These elements take loads from horizontal building elements – CLT slabs and GL and steel beams.

Floors are made of heavy gravel and cement screed over CLT slabs.  This makes bigger dead loads, but helps with vibration of long single span slabs with maximum span of 6 m.

CLT slabs are supported directly on CLT walls or steel beams. Steel beams are hidden in floor layers and aligned on bottom surface with visible CLT. Single span beams are supported on 120×160 mm GL columns that are aligned with visible CLT walls. Most walls are 120 mm thick, but due to fire protection criteria, walls that are visible and exposed to fire from both sides are made of 160 mm thick CLT panels.

Horizontal stability of building is secured with external and internal CLT walls. Since the building is hidden and sheltered from most sides by other existing buildings, there are very few windows and doors in the walls. This means more elements which resist horizontal forces and also smaller wind loads on the building. As the building is located in Netherlands, there is no almost any seismic activity.

Because of no access from the outside, panels need to be fixed from inside only. As surfaces on external walls are visible, we needed to find solutions for adequate fixing and brackets that can take loads and don’t affect visual surfaces.

Acoustic requirements of building are met with soundproofing stripes in wall to slab joints and under steel brackets.

Building is designed, produced and assembled in the summer of 2021.




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