Turning to History and Science in Order to Preserve Wooden Shingles in Sweden

The use of wooden shingles as a building material has a long tradition in Scandinavia, going back to medieval times. Unfortunately, knowledge regarding manufacturing, quality, and maintenance of shingles has been partly lost and without it we cannot properly preserve the precious historic values of shingles. A recent project on wooden shingles on churches in the dioceses of Strängnäs and Västerås in Sweden investigates why, in too many cases, relatively new shingles have proven to be less durable than old ones and demanding more maintenance in comparison to older ones. 300–400 year-old wooden shingles in the study demonstrate outstanding sustainability, hold unique values, and have to be handled with great caution. The main purpose of the project has been to increase knowledge on shingles as a façade and roof covering throughout history in order to obtain a deeper understanding of the material. In an attempt to find out about traditional manufacturing methods, surface treatment and maintenance of shingles as well as how conservation principles have varied over time, we turned to the archives. In order to find out more about the quality of the wood and the surface protection of the shingles, tar in most cases, different methods of scientific analysis have been carried out. Through X-ray of shingles, chemical analysis, and analysis of mold and rot, we have been able to thoroughly investigate the properties of the wood and different surface treatments as well as the decay of the wood. The different types of analyses and approaches stated above give a comprehensive picture of which factors that work in the long-term perspective. The results will be an important tool for authorities in approving interventions and of use for property caretakers. It is hoped that the results—in the long run—will lead to reduced maintenance costs for the parishes, paired with greater caution during renovation.