Kv Tvättstugan, an apartment building with massive wood construction : A thesis about acoustic and fire requirements and a comparison of energy and moisture aspects

Title: Kvarteret Tvättstugan, an apartment building with massive wood construction. A thesis about acoustic and fire requirements and a comparison of energy and moisture aspects. Earlier restrictions in the Swedish legislation have resulted that only a small percentage of the apartment buildings that have been built are designed with a massive wood construction. It has been allowed to build unrestricted with wood since 1994 as long as the function of requirements are fulfilled. This change in the rules together with the great environmental benefits of wood has led to that more companies choose to build apartment buildings with wood. One of these companies is Folkhem Production AB. Kv. Tvättstugan in Sundbyberg is Folkhems first big investment and it consists of four eight-storey buildings with constructive components of massive wood. It is not only the bearing system which is of wood, but also the entire front material.Folkhem took the initiative to this thesis so that they could evaluate the pros and cons of various building systems. The task was to compare two different building systems from the suppliers Kaufmann Holzbau GmbH and Martinsons Byggsystem AB. Kaufmanns system consists of doweled wooden beams and the floor structure is an assembled structure of wood and concrete. Martinsons system consists of cross-glued wood, which is abbreviated KL-wood. To get an idea of the differences between wood and concrete, the two systems of wood are compared with a concrete wall that Folkhem has used in previous projects. The building components that are compared are the exterior walls and the floor structures, and the connection between them.Both hand calculations and calculations with three different computer programs have been made to make the comparisons. Since the project kv. Tvättstugan is not completely designed, some assumptions have been made in cases when data are lacking. U-values and thermal bridges were calculated in the simulation software Comsol. The hand calculated U-values are consistent with the data calculated in Comsol. The results show that the concrete wall has a higher heat flow than the two wooden walls. VIP-Energy was used to calculate the energy consumption of a house with Kaufmanns construction and the concrete construction. Both of these construction systems fulfils BBRs requirements, but the Kaufmanns system has lower energy consumption. Since wood has a low critical moisture condition, it is important to study the relative humidity accurately in the wood materials. This has been done in the program Wufi and the results indicate that the outer walls dry out between the weather changes.After the studies of six existing multistore apartment buildings with wooden constructive elements, it has been observed that the acoustics and fire issues often can be a problem. These two areas are described in a greater depth for this reason. Important concepts in these areas and the Swedish requirements are described. As for the acoustics mainly the surroundings has been studied to see which arrangements can be made to fulfil the national acoustic demands. A preliminary copy of the fire protection documentation has been made for kv. Tvättstugan to meet BBRs requirements and it has been studied and some of the most important ones is shown. The three designsolutions meet the Swedish requirements according to the calculations and simulations that have been made in the thesis. We think that it is good that Folkhem chooses to build an apartment building with massive wooden construction supplied by Kaufmann. This will benefit the development of wooden constructions in Sweden. Folkhem can learn new construction techniques that are not currently used in Sweden by bringing in a German company.