Montana Kaimin, September 17, 2003

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/5781/thumbnail.jp

Hvordan lykkes med etablering av naturbaserte løsninger for overvannshåndtering

SINTEF har utviklet en praktisk veileder for å sikre bygg og infrastruktur mot klimaendringer.publishedVersio

Partnerskapets innovasjoner

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Pilotprosjekter

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Verktøy og veiledere for klimatilpasning

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Spesialister i klimatilpasning

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Moisture robustness of eaves solutions for ventilated roofs – experimental studies

Ventilated pitched wooden roofs with eaves (roof overhangs) is a common building practice in the Scandinavian countries. The eaves are protecting the façade from rain, wind driven rain (WDR) and snow, and it covers the roof ventilation aperture. The eaves should be designed so that the least possible amounts of rainwater and snow enters the ventilation aperture between the roof cladding- and underlayer roofing. At the same time, adequate ventilation of the roof must be ensured to promote proper drying-out capabilities of the roof and to avoid problems of snow melt and ice formation at eaves and gutters during winter season. Small or almost nonexisting eaves is a trend in modern architecture. It is a common perception that such solutions are more vulnerable to moisture damages due to possible increase of water penetration into the roof aperture. The aim of the study is to experimentally investigate the moisture robustness of the described risk area and to find answers to how the design of eaves influence the amount of rain that is driven on to the underlayer roofing under the aperture in ventilated roofs. It was found that the amount of collected water in the different test series to a large extent are given by the water droplet size as well as the wind velocity inside the air cavity. The results from this study simulates an example of a rain event with heavy rain intensity and strong winds (storm). The test represents an example of a storm event with a given droplet size distribution. The results indicate that an increased pressure drop decreases the water ingress. Comparative tests showed that installation of a wire mesh largely decreases the measured water collection and the dynamic pressures inside the air cavity

Moisture safety strategy for construction of CLT structures in a coastal Nordic climate

To reduce the carbon impact of new buildings, wood is seeing increased use as a structural material. Cross-laminated timber (CLT) and glue-laminated wood (glulam) elements allow the construction of multi-storey buildings. However, wood is vulnerable to moisture, especially when naked wood is exposed to weather during the construction process. This paper presents the moisture strategy employed during the construction of a four-storey CLT/glulam building in Trondheim, Norway. The building was constructed without the use of a weather-protective tent, requiring alternative protective measures. The construction of the main structure was scheduled to be as short as possible. Local protective measures were employed to protect the structure from rain and free water was removed after rain events. The project was closely supervised by the client, with particular care for moisture control. Moisture was regularly measured at 50 points throughout the building. No wooden surfaces were encapsulated until a wood moisture content below 15 weight-% was measured. The performance of the moisture strategy was evaluated using measurements of wood moisture, indoor climate, airtightness, and visual inspections. The wood moisture content quickly decreased as the building envelope was assembled, indicating that drying was well facilitated. In the first year after construction, gaps between the flooring and baseboards were observed, suggesting that the wooden elements have experienced some shrinkage. The moisture safety strategy is deemed to have been generally successful. The overall experiences were important in the development of new recommendations in the SINTEF Building Research Design Guides for CLT structures.publishedVersio