Material och uppbyggnad vid renovering av reveterade skiftesverk : En analys ur fuktsynpunkt

Sammanfattning: Boule houses are a type of timber construction. The houses have been used since the middle ages in Sweden and some of them still remain today. A rendered boule house wall is open for diffusion and able to buffer moisture. Rendered boule houses are a cultural heritage. The expression if the facades should therefore be preserved and the thickness of the wall should not be changed. When rendered boule houses are renovated the construction of the wall is sometime changed and the lime render is partly replaced with insulation. This report investigates the prefered materials and construction techniques to reduce the moisture in the wall. The goal is to contribute the knowledge base regarding moisture risks when renovating these walls.   WUFI and Folos diagram were used to study 17 wall types. The program and the diagramm provided information about relative humidity, temperature and duration of critical periods for the chosen wall types. Wood fiber insulation with the ability to buffes moisture was compared to mineral wool that lacks this ability. Three different types of mortar were studied, namely; air hardened lime mortar, hydraulic lime mortar and lime-cement mortar. Four different construction types are included in the report. The first represent an original lime rendered boule house. The second is insulated without an air gap and the third includes an air gap. The fourth construction type has no air gap but an insulation board is placed between the mortar and the wooden pillar. The fourth wall type was only studied with the hydraulic lime mortar.   Interviews and litterature studies were preformed to gain knowledge of what material and which constructions that are of interest to investigate. The amount of critical moisture hours for two different layers in the wall was presented. The layers were chosen where the wood is specially exposed. To clarify the result further chosen periods where studied. Finally, the result lead to a discussion regarding the mortar and the insulation’s ability to buffer moisture. The conclusions were that the lime-cement mortar led to more intense and longer critical moisture periods. It also seemed like an insulated pillar was better off than pillars in direct contact with the mortar.