Klaproos Boxmeer CLT building

Recently, the apartment complex De Klaproos in Boxmeer was completed. The Newomij project consists of 18 apartments built in CLT. CLT (Cross Laminated Timber) is a type of timber composed of layers of spruce wood, glued together crosswise. These prefabricated building elements—mainly floor and wall panels—are used to create solid timber building structures.

CLT is known as a sustainable, renewable, and circular material with low CO₂ₑ emissions. As a naturally grown material, it even stores CO₂. In addition, construction with CLT requires significantly fewer CO₂-intensive materials such as brick and concrete. Timber is relatively lightweight, which makes it critical in terms of sound insulation, and therefore demands specific design solutions.

As acoustic and fire safety consultants, we have been involved from the very start of the design phase, advising on the architectural concept, material selection, and detailing of all joints and connections in building nodes to achieve the required sound insulation. Not only the composition of the direct separating constructions—such as floors and walls—plays a role, but especially the build-up of flanking constructions (such as façades and roofs) and the degree of (de-)coupling at the interconnections.

By using a detailed calculation method for airborne and impact sound insulation, combined with experience from other projects and product information obtained from abroad, we were able to prepare a reliable prediction for application in the Dutch context.

To ensure the intended quality was actually achieved, regular site inspections were carried out during the construction phase in Boxmeer, along with interim measurements to monitor progress and construction methods, making adjustments where necessary. At completion, Peutz conducted extensive measurements of airborne and impact sound insulation for as many critical separations as possible, to assess compliance with requirements and to compare with predictions. The measurements show that the intended final quality was indeed achieved, with all measured separating elements meeting or exceeding the Dutch Building Decree / BBL requirements. The floors perform at least 10 dB better, enabling residents to use hard floor finishes without any issues.

It can be stated that the high quality aimed for from the outset has indeed been achieved, largely thanks to the dedication and involvement of all parties involved in the design and construction. Peutz was able to contribute its expertise as acoustic and fire safety consultant from the initial design phase through to on-site inspections during construction and final acceptance testing. We are proud of the end result and look back on a successful collaboration with all parties involved. The result also reinforces the confidence that it is possible to meet Dutch sound insulation requirements for apartment buildings constructed in CLT.