Påbyggnad av flerbostadshus i Umeå : Tillvägagångsätt och möjligheter vid beaktande av markförhållanden för lamellhus

Sammanfattning: The present study addresses storey extensions on apartment buildings within Umeå municipality, mainly focusing on lamella houses. In Umeå, the number of residents is in steady increase. Simultaneously, there is an ambition among local politicians to maintain a moderately small city center. Subsequently, the population growth becomes a considerable challenge, as the building surface is clearly limited. Hence, storey extensions on existing apartment buildings can be a suitable solution for new construction. Accordingly, the study aimed to investigate possible approaches and opportunities to storey extensions as well as ground conditions for lamella houses. After examining approaches to storey extensions, lightweight buildings in wood and lightweight construction in steel was found appropriate due to low self-weights. By applying a reference building with superficial foundation, different ground conditions were compared in order to explore if they are affected differently when an increased mass is added in form of storey extensions. The study found that city areas with abundance of shallow bedrock or subgrade by the character of friction soil have good conditions for storey extensions with lightweight material such as wood and certain steel techniques. However, in areas containing soils of cohesion character, the risk for subsidence or other damages in the event of cracks in the ground is considered to be large. Through diligence control of ground conditions, storey extensions in both wood and lightweight construction in steel can provide good opportunities for future storey extensions on apartment buildings within Umeå municipality.