Fuktsäkerhet hos lätta prefabricerade utfackningsväggar : En studie för att öka fuktsäkerheten hos lätta prefabricerade utfackningsväggar med träregelstomme under byggtiden

Sammanfattning

Many construction contractors today use lightweight prefabricated infill walls. These walls consist of a timber or steel frame with varying degrees of prefabrication. Due to moisture issues, in many cases, walls with a low degree of prefabrication are used, resulting in longer construction times compared to when walls with a high degree of prefabrication are used. A survey involving 65 construction companies and public housing companies revealed that nearly 40% of respondents prefer concrete infill walls over lightweight infill walls due to the risk of moisture problems, which is worse from an environmental perspective. The study presents underlying theory regarding exterior walls, moisture, the impact of moisture on materials, and potential risks of moisture problems when using lightweight prefabricated infill walls. The purpose of the study is to identify risks that may lead to moisture leakage in lightweight prefabricated infill walls during construction so that more secure constructions can be built in the future. The goal of the work is to develop standard solutions for lightweight prefabricated infill walls that are moisture-proof during construction without the need for external weather protection. The method used to determine this was a qualitative interview study with professionals in the construction industry. Additionally, Copilot, a tool for generative artificial intelligence, was used to investigate its usefulness for this type of problem. The results show that moisture leakage has primarily been detected at the joints of the wall blocks due to leaks around top plates and leaks at vertical joints. Leakage around top plates could occur before the installation of structures over the walls, but also afterwards. When moisture has penetrated into a floor form's mineral wool insulation and the insulation between balconies and floor slabs, the latter could penetrate the walls through leaks around the lintel. Water accumulation at the edges of floor slabs has also led to leakage around top plates. The study proposes solutions that could reduce the risk of moisture leakage. The proposals are based on covering details with an external weather protection and an internal adhesive membrane on timber studs and top plates, as well as expansion joints at vertical block joints and around windows. Using a floor form that creates a tight joint with the floor slab, insulation in the floor form with closed pores, and quickly completing membranes at balconies are suggested. Using top plates and studs at steel block joints could be a way to mitigate the consequences of moisture leakage. The generative artificial intelligence tool, Copilot, was found to provide overall descriptions of where moisture leakage may occur in lightweight prefabricated infill walls, similar to the descriptions from the interview study. However, deficiencies were discovered when more specific answers were requested.