De Boetzelaer swimming pool in Monster, burned down in 2019 and festively reopened in 2021: Ashed swimming pool is rebuilt at lightning speed with additional fire-resistant building envelope

Construction company De Vries en Verburg of Stolwijk dared to take on the challenge. When work restarted after ten months, the design phase had not yet been completed. A well-oiled and well-coordinated construction team ensured that in June 2021 a beautiful new swimming pool could open its doors to the recreational public of Monster and the surrounding area.

Jan IJzerman is manager of Special Projects at Xella, supplier of the aerated concrete fire walls for the swimming pool. He explains that Xella also performed the drawing, engineering and assembly work for De Boetzelaer. "It specifically involves an interior cavity wall to which the exterior cladding is attached. A fire-safe shell is a priority on this project." Aerated concrete is highly fire-resistant and it is an easy material to attach cladding to. In addition, this precast aerated concrete system is flexible in the engineering and in the drawing work, which allows rapid switching with other building parties in terms of specifications, as in the case of adjustments to the supporting structure that were still made during the construction phase. 

Durable, chlorine- and acid-resistant coating

Ronald Roubos is a work planner at De Vries en Verburg. He explains that the wall of the swimming pool adjacent to the adjacent sports fields must meet the legal requirement of 180 minutes of fire resistance. "Because the entire inner shell is fitted with Hebel aerated concrete, the entire facade meets this requirement. Even though this is not required by law for the entire building envelope." The building is divided into different fire compartments. The columns are also clad with the fire-resistant Hebel plates. The Hebel roof and wall plates are placed on the inside against the steel structure of the building, forming a fire-resistant shell. The reinforced walls are 150 mm thick and the roof plates are 200 mm thick. The Hebel sheets are coated on the inside with a special hygienic coating that is resistant to chlorine and acid vapors and moisture.

Rapid and optimal fire resistance

The task was not only to build a new, fireproof swimming pool at lightning speed. The abstract design of the building also had to fit seamlessly into the project. When construction of the new pool began in late 2019, the design phase was still in full swing. The unusual design required customization. 

Spectacular design

Siu Kin Shek, involved in project as architect of BAS1S Architects, explains that the facade finish is made up of equilateral triangles of one and a half meters that are rotated in the facade. The basis of this building is a steel structure that can be quickly built and made windproof. In consultation with Xella, De Vries en Verburg designed the steel structure. This means that the design was tinkered with during the construction phase, because there was too little time for this in the preliminary phase. This was a major challenge for both the contractor and Xella. The building has large spans with curtain walls. Due to the specific design of the main steel supporting structure, the Hebel sheets are easy to assemble. "Because at a swimming pool you have to deal with temperature differences, a humid climate and chlorine fumes, facade cladding with an intermediate structure of aerated concrete walls is best suited for this," Shek explains. "The elements are stony, quick to install and you don't have to drill through the steel structure."