This bachelor thesis has been performed as a literature study and consists of pros and cons considering test methods, sustainability, cost efficiency, legislation and environmental effects of flame-retardant wooden façades. The study also handles the possible consequences from the lack of permanency of the flame retardants in wooden façades due to leaching. Wood is a construction material with unique possibilities regarding the environmental aspect since it is renewable. For a matter of fire safety, the usage of wooden façades brings several challenges that must be considered during the projection of a building. Wood is a flammable material which increases the risk of fire spread along the façade. According to "Boverkets Byggregler, BBR" a Swedish collection of construction regulations, wooden façades must be protected when used in non-sprinkled buildings with three or more floors. Flame retardants in forms of fire impregnation and anti-flammability paint are therefore used as protection of the wooden façades. Façades main task is to protect the inner parts of the building from tough outdoor weather conditions which makes the façades vulnerable for leaching of the fire impregnation and anti-flammability paint which can affect the fire properties negatively over time. There are several ways of testing the fire resistance of wooden products. The regulations in BBR for using wooden façades in buildings with three of more floors without sprinklers, states that the product must be tested and approved according to SP Fire 105. A test method that does not takes in consideration that the flame retardants might decay over time, but there are other methods for testing and classing the permanency of the flame retardants. DRF classification EXT (Durability Reaction to Fire for External use) can be accomplished by using the European test method EN 16755 that exposes the wooden façade too accelerated weathering by cycles of watering and dry outs. Although this is not something that are clearly stated in Swedish regulations but is used as a quality stamp or guideline by manufacturers. The results from foreign weathering methods differs to the results generated through weathering methods by the Nordic method NT Fire 054. The results from the Nordic method turned out to be the least conservative of the ones tested. A relation between time to ignition, amount of cycles and time per cycle was observed for all test methods, but which method that are most precise has not been determined. Results from previous studies where products were exposed to natural and accelerated weathering has been compiled. The results suggest that several products do not meet the requirements of DRF class EXT, mainly due to the cause of leaching of the flame retardants. The regulations in BBR is in this study considered too vague due to the lack of distinct demands of how to acquire permanency of the fire protection for wooden façades. It was also acknowledged that the most common fire retardants have a minimal negative impact on the environment due to leaching. Fire impregnated wooden façades stands economically strong on the market compared too other construction materials. The benefits of using wood as a construction material is that its lifecycle has low emissions of carbon dioxide, is more energy efficient and is aesthetically appealing. The disadvantage of using wood as a construction material is that it is flammable regardless which type of protection that is used which entails austere building regulations compared to diverse façade materials.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:ltu-78943 |
| Date | January 2020 |
| Creators | Grönlund, Oskar, Winroth, Alexander |
| Publisher | Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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