Extensiva gröna tak : En byggteknisk studie om takgenomföringar och de gröna takens problematik

Sammanfattning: This report is made by students from the bachelor programme in construction engineering at Uppsala university and it covers different pass-through roofing methods on extensive green roofs. The report also examines which existing solutions need further development. Eighty percent of all leakage occurs where vertical and horizontal surfaces meet as in pass-through. Hence, well planned solutions are required that counteract the risk of leakage at critical section. In Sweden there are currently no standards, guidelines or certifications for extensive green roofs. The extensive green roof offers a delay of rainwater, but this attribute also causes problems such as an increased moisture load on the entire roof, but especially on pass-throughs. The report, consisting mainly of literature and interview studies, has investigated and assessed pass-through solutions. The report has resulted in improved solutions consisting of the fact that perforation should be raised above the surface of the superstructure to reduce the exposure to moisture. To reduce moisture load around pass-troughs, it is also recommended to construct a gravel layer and a boundary plate that prevents vegetation from spreading. The spreading of vegetation and the occurrence of undesired vegetation must also be counteracted by maintenance, which should be performed at least twice a year, spring and autumn. A well-known opinion in the field of construction is that extensive green roofs are not in need of root protection, but as the occurrence of unwanted vegetation may have undesirable effects on the roofing membrane of the green roof, the use of root protection is always advocated.