Sammendrag
Rain damages constitute an increasing share of building damages in Norway, and the rain exposure is expected to increase in the future. The air sealing of the rough opening around sliding doors is vulnerable to lacking design and poor execution, and thus vulnerable to leaks. Universally designed door sills experience a greater water exposure as the sill cannot be elevated above the deck. Despite of, or perhaps because of, rain-proofing of door sills being challenging, there is a lack of literature covering design and execution of the rough opening.
Manufacturers of sliding doors seldom state how the rough opening should be designed, and previous studies show that the planning can be insufficient or completely absent. With lacking work drawings and several disciplines being involved, the execution can be random and improvised on-site. To contribute to more robust solutions for sealing of the rough opening around heavy sliding doors, full-scale laboratory experiments were carried out in collaboration with SINTEF, Norgeshus, NorDan and Isola as part of the project Verktøykasse for klimatilpasning av boliger (Toolbox for Climate Adaptation of Dwellings). The solutions were tested without metal flashings or other protective cladding to provoke leaks and highlight weak points. To assess the raintightness, the rough opening was observed from the inside during the tests and observed leaks were noted down. In addition to laboratory experiments, proposed solutions in the SINTEF Building Research Design Guides (''Byggforskserien'') were studied to obtain an overview of which solutions are recommended and to identify weaknesses. Of the five rough opening sealing solutions, only one was rainproof at 600 Pa air pressure exposure. Solutions with different materials in different rough openings, and possibly different planes, which are recommended in the SINTEF Building Research Design Guides, had leaks in the corners where these materials were connected. Norgeshus' preferred solution with four stripes of caulk by the sill and adhesive construction tape covering the sides and top failed at 450 Pa. Solutions where sealing materials were applied before the door was placed led to twisted rubber gaskets and compressed caulk. The best-performing solution used two-sided flexible tape from Isola. This solution was rainproof up to 1050 Pa before the glue started peeling off. In another promising solution the door was lifted by a thin ''EPDM plate''. Caulk was applied in all rough openings, but the work was time-consuming, difficult and vulnerable to errors. Common for the good solutions was that the sealing materials were applied after the door was attached to the frame, and that the solutions used continuous and flexible sealing materials applied in the same plane. The SINTEF Building Research Design Guides recommends solutions that require connections and the connections are vulnerable. Additionally, the solutions in the SINTEF Building Research Design Guides do not take into account that the sill on sliding doors is thin and exposed to high loads so that support packers must be narrowly spaced, and the spacing distance is not always given by the door manufacturer. The air sealing of the rough opening around sliding doors should be continuous and of the same material, and the rough opening must be accessible during assembly for good results.