Safety and durability of CLT-balconies

Abstract: The growing popularity of cross-laminated timber (CLT) in the construction industryhas resulted in a demand for research focusing on the construction and design of CLTbalconies. This paper aims to address this need by presenting a CLT balcony design aswell as investigating its structural stability and moisture safety. The ultimate goal is toenhance knowledge and provide a solid foundation for the construction sector to furtherevaluate the feasibility of building CLT balconies.The purpose of this study is to investigate whether it is possible to design durable and safeCLT balconies in terms of structural stability and moisture safety. The structural stabilityis examined through calculations by EKS 10, the Eurocodes, and the CLT-handbook. Byemploying these calculations the study aimed to determine whether a CLT slab can safelysupport the anticipated loads subjected to a balcony.Moisture safety is examined through literature studies as well as interviews to gain knowledgeand insight into general practices, challenges as well as opportunities in the constructionsector. Consequently, the goal was to identify measures that enhance the long-termmoisture safety of CLT balconies.The research methodology is a combination of calculations, literature studies, and interviews.Based on this knowledge, a considered CLT balcony design is presented. Thedesign consists of a CLT slab placed in a steel frame of L-profiles, which is further supportedby tie rods. The CLT slab is further designed to be lifted from the L-profiles byusing battens, to ventilate the area between the L-profiles and the CLT. The design alsoaims to avoid connections and attachments to the CLT slab, to keep the sealing layertight and thus reduce the risk of moisture ingress.The results of this study show that from a structural stability perspective, the CLT slabcould safely support the anticipated loads subjected to a balcony. The results furtherindicate the possibility of dimensioning down the CLT slab, which however would increasethe sensitivity to vibrations and sagging, possibly generating an unsafe feeling for users.From a moisture safety perspective, the results show that several parameters influencethe final moisture durability. Amongst others, these are parameters such as avoidingattachments to the CLT slab, keeping the sealant layer tight, and designing detailedbalcony solutions.By combining calculations, interviews, and literature studies, this paper contributes anddevelops the knowledge base regarding CLT balconies. The construction industry couldbenefit from the outcomes of this research, which could contribute to the further developmentof guidelines and recommendations for designing moisture-safe CLT balconies.However, further studies are recommended regarding for example environmental impact,economic costs as well as a cold bridge analysis to evaluate the feasibility of constructingCLT balconies.