Sammendrag
After the Second World War, many small houses were built which today are considered poorly heat insulated. These need an upgrade to meet the current need for energy efficiency. Through the research project OPPTRE, new solutions for energy upgrading of wooden dwellings are investigated, where, among other things, moisture safety is in focus. Traditionally, pitched ventilated roofs have needed a vapor-open layer against the outdoor air to be able to dry. With a smart vapor barrier, moisture transport to the indoor air is possible, which enables new possibilities and solutions that have not previously been possible without a high risk of moisture damage and mould growth. In this thesis, a solution for retrofitting pitched ventilated roofs in wooden dwellings using a smart vapor barrier has been investigated. Based on gable roofs from 1950 to 1980, the solution needs less work than recommended retrofitting solutions, and the lowering of the ceiling to the inside can be reduced. The thesis has been carried out as a parameter study, with calculations of the roof structure in the hygrothermal simulation tool, WUFI 2D. The add-on WUFI Mould Index VTT is also used for calculating mould growth. A selection of parameters that varies in dwellings, and which are assumed to have an effect on the roof's drying ability or risk of mold growth, are varied in the calculations. The results of the parameter study show that it is mainly a challenge to get a high enough heat contribution from short-wave radiation, for the roof to have good enough drying ability. Orientation, roof slope and geographical position affect the short-wave radiation intensity on the roof surface, and the absorption for solar radiation affects how large the heat contribution from the radiation is. With a low heat contribution, moisture accumulates in the roof without the possibility of drying out. With a high heat contribution, the drying effect can also compensate for other adverse effects. If one assumes low embedded moisture and low moisture excess, the construction can be favorable in many conditions. Conservative orientation of the roof surface to the north then has sufficient drying ability in almost all of Norway. If you close the roof early in the summer, the roof can also withstand higher levels of starting moisture. Three smart vapor barrier products have also been investigated, where the biggest difference between them has been found to be the drying ability in the summer. AirGuard Smart has the best drying ability for all calculations compared to the other two smart vapor barriers, Majrex and Intello. When compared with a roof structure with a traditional vapor barrier and a vapor-open sub-roof, the traditional solution is more robust for embedded moisture and high moisture excess than the solution with a smart vapor barrier. This can be seen in the fact that the traditional roof structure has a faster drying time and dries to a lower total moisture content. The traditional roof construction also appears to be more robust in that it does not depend on heat contributions from short-wave radiation.