Developing new methods to improve conservation of turf houses

Turf houses are a quintessential part of Iceland’s architectural and cultural heritage. Some have survived for centuries and give us a unique insight into how our ancestors lived. These days, most turf houses are uninhabited historical buildings, which can pose complex challenges. Turf as a building material can be tricky to understand—until now, that is. For the first time, a new study is investigating turf houses using methods from civil engineering. 

Planning to monitor several buildings at once

Dórótea Høeg Sigurðardóttir, assistant professor at the UI Faculty of Civil and Environmental Engineering, is now working with a team of experts from UI and the National Museum of Iceland on a study designed to improve our understanding of the building physics and structural behaviour of turf houses, with the aim to develop more effective conservation methods. The team includes experts in Icelandic architectural heritage, building conservation, civil engineering, building physics, structural health monitoring and materials science. The project involves both field and lab research.

“This is a collaboration between the National Museum of Iceland and UI. The people in charge of the historic buildings collection at the National Museum needed engineering advice and help developing methods for monitoring many turf houses at once and prioritising maintenance work,” explains Dórótea.

Mud houses of various kinds can be found all over the world and turf houses are not unique to Iceland, but Icelandic turf houses differ from examples in other countries. There have been studies looking at vernacular architecture in EU countries and no other nation builds houses in exactly the same way as Icelanders.

Turf houses vary from region to region

This is the first research into Icelandic turf houses using methods from civil engineering. The goal is to develop procedures for monitoring turf houses, so that decisions about maintenance can be based on objective data. This is achieved by measuring humidity levels and temperatures and looking at movements in the timber frame using a 3D scanner, which allows the team to evaluate the condition of the building and better understand turf as a material. The team also aims to develop these procedures in such a way that they can be used to monitor many buildings at once, increasing the effectiveness of maintenance work.

The project won a Rannís grant in early 2024, and measuring instruments were set up at Keldur in Rangárvellir in the spring. The team has also been collecting data from Laufás in Eyjafjörður for around a month. The team decided to start by looking at buildings in the north and the south in order to explore differences between turf houses in different regions, specifically differences in the thickness of the turf and how the roof is constructed.

Dórótea explains that these differences are, to a certain extent, due to climate. “People were able to use more turf in the north because the winters are usually colder there, with fewer fluctuations in the weather. This helps the turf hold its form better. In the south, houses were usually built from stone and turf and people tried to cover most of them with a layer of living turf to protect them from rainwater. In the north, the climate is dryer and colder, so there is less need to make sure the soil is not washed away,” she says.

The project is still in the early stages, so no results are available yet. “Our early analysis shows that it was a very wet summer and the turf is holding a lot of moisture. But we haven’t gone any deeper than that yet. We are mainly collecting data right now and haven't reached the analysis stage.”

A living building material that requires maintenance

The properties of turf as a building material are not as well understood as many other materials. Turf is mainly soil that contains extensive root systems, with a top layer of living grass. Since this is a living material, Dórótea is certain that the team will observe movements, but they do not yet know how fast those movements are. The first images from the 3D scanner have provided some initial impressions, and further scans conducted in the spring, summer and autumn of 2025 will create a more complete picture. This is a three-year study, but the methods under development can be applied far beyond the end of the project.

Dórótea explains that if a gable is left without maintenance, it is likely to collapse within about thirty years. “Most of these houses owned by the National Museum were inhabited by the gentry. They were often clergy houses, so most of the surviving buildings were the homes of wealthy people. Very few of the houses are ‘original’, because they require constant maintenance. They need to be regularly restored. We know that the people who lived in these houses rebuilt sections of them almost every year. Parts would need to be taken down and completely rebuilt. So not much of them is original in that sense. The way they are constructed is original and the way they look, but the materials themselves are not,” she explains.

Other challenges in caring for uninhabited historical buildings

This project is significant for its scientific value, but also for its value to Icelandic culture.

“In a scientific sense, learning more about turf as a building material is very interesting. Would it make sense for us to use it more? Do we want to better understand its insulating properties? Its potential for channelling water away?” asks Dórótea.

She points out that turf houses are an important part of Iceland’s cultural heritage. Those entrusted with taking care of them must know how to do so, and it is vital that this knowledge is not lost. “Nobody lives in these houses any more. They are historical artefacts. This in itself changes the behaviour of the building to a certain extent, because the internal temperature is not the same. They are probably damper. Houses are dryer when people are living and cooking in them,” she points out.

Dórótea is excited to see what results the research will yield and hopes that the team will be able to create an accessible handbook for the conservation of Icelandic turf houses.

Author of the article: Ísabella Sól Ingvarsdóttir, BA-student in Journalism.