NET – Managing our Natural and Cultural Assets
‘Can turf be revived as a contemporary building material?’
Iceland Date: 18.07.2016
This report summarises the findings of a 7-day visit to Iceland during June 2016. The trip was funded by Erasmus+ and organised by Libby Urquhart on behalf of the ARCHnetwork and was primarily undertaken to investigate how we can Manage our Natural & Cultural Assets focusing primarily on Icelandic turf building. During our trip, led by Bryndis Zoega (Skagafjörður Heritage Museum and project manager for the Heritage Craft School), we studied the heritage of turf building, traditional tools and construction techniques, appropriate repairs and maintenance, examined precedents of traditional turf buildings and witnessed the threats that are imposed by tourists on these buildings of great cultural significance.
With a background into this building technique and awareness that turf buildings are close to extinction along with the skills and knowledge of experienced craftsman, the reports explores if turf building could be used in a contemporary way to revive this building technique. New buildings would help sustain the specialist skills and knowledge whilst protecting the traditional buildings from the threats that are imposed from the mass number of tourists who visit Iceland.
The report concludes with observations with how to pursue designing new turf buildings, the need for rigorous tests and monitoring to see whether the problems of the material and mass occupant numbers can be overcome and fulfill the present demands of the tourism and construction industry.
1 Background into turf BUILDING
1.1 Timeline perspective of settlement in Iceland
Iceland was one of the last countries to be settled arguably suggesting that turf building is one of the youngest of the traditional building techniques.
Surviving examples of turf construction can be found in Greenland, Ireland, Scotland and Norway but due to wetter climates and a surplus of timber, these other EU countries adapted alternative methods of construction; this means that the largest collection of turf buildings are found in Iceland.
1.2 Why use turf for construction?
In the late 9th century, the Norse Settlers arrived to a vast land of volcanic geology, shrubs trees and turf. Timber was prioritised as fuel for heating and smelting iron and served no purpose for construction, rapidly resulting in mass deforestation, (Fig.01).
Due to the limited palette of local materials, turf was considered the only appropriate building material for it was easily available, locally sourced and has high thermal performance to insulate during long periods of sub-zero temperatures.
1.3 Why is turf no longer used for construction?
Iceland is currently experiencing a movement of mass urbanization as farmers and rural dwellers are migrating to Reykjavik and other larger towns, (Fig.02). Whilst rural living is in decline, trade links to neighbouring EU countries enable import of foreign building materials, prefabricated kits and mass import of cement for concrete construction, (Fig.03).
Space is limited within the urban areas squeezing the footprint to which you can build on. With high ratios of wall width to height, the footprint requirements of turf buildings are not practical for constrained urban sites. The ideal place to build with turf is in the rural environment where it is spacious. As rural living is in decline, the demand for turf buildings are declining respectively.
Turf is a living material that requires regular maintenance and can rapidly deteriorate if not maintained, (Fig.04). If maintained without sufficient knowledge or skills, the problems can be exasperated and consequently lead to accelerated deterioration. From observation and conversations with various Icelanders, it is clear that the population predominantly desire buildings of low maintenance.
1.4 How was turf used for construction?
The traditional Icelandic turf house is primarily constructed from a stone plinth, turf walls, load-bearing timber frame and a turf roof. Turf buildings were initially built in a circular form with open plan living and central fireplace, with property boundary enclosed within a perimeter wall, (Fig.05). As standards of living evolved, additional rooms were integrated with new layouts progressing into new designs that refigured the entire layout around the principal bathing area; evolving into the saw-tooth, timber gabled turf houses that are most prominent today, (Fig.06).
Fig. 1: Treeless landscape Fig.2: Urbanisation, Reykjavik
Fig. 3: Mass use of concrete Fig.4: Deterioration of Turf
Fig. 5: Illustration of original turf house Fig.6: Gabled turf houses
2. The Future of Icelandic turf buildings
2.1 Impacts from Tourism
Since the volcanic eruption of Eyjafjallajökull in 2010, Iceland has experienced an exponential growth in tourism numbers. It is forecast that Iceland would accommodate approximately 1.6 million visitors by the end of 2016; 483% greater than the current Icelandic population of 331,000.
Iceland’s turf buildings have also been nominated on the UNESCO ‘tentative list’ making them a prime sight for the tourists who visit the island. Turf buildings are living buildings and susceptible to temperature fluctuations, excessive humidity levels, visitor touch, wear and tear. The turf buildings that survive were never designed to perform to the conditions that mass visitors create and are therefore vulnerable to deterioration. Once defective, with an absence of maintenance and a limited awareness of the changes to the internal conditions, non-visible defects can manifest behind the internal fixtures and fittings causing the buildings to rapidly revert back into the ground.
2.2 Conservation Philosophy
The question of whether the surviving turf buildings should be adapted with modern interventions such as ventilation measures, composite components or synthetic materials needs to be addressed. These intrusions could help sustain their existence from the visitor-imposed threats whilst consequently breaking the philosophy of conservation that remains true to the original construction. Examples of this were visible from our visit to Nyibaer when modern interventions were blatantly installed to combat the visitor related problems (Fig.07/08) helping to preserve the building compromised by an inaccurate interpretation of the original construction.
2.3 New buildings
It funding permitted, new turf buildings could be built to showcase the turf building tradition whilst helping protect the surviving buildings of historical importance. Alternatively, the deeper factors of the decline of turf building could be addressed and new contemporary buildings could be built to revert the mindset of locals and visitors into a new future for turf building.
One example of a new turf building was identified in Varmahlíð where modern materials and interventions were integrated to form an attractive tourist gift shop, (Fig.09/10). It is too early to witness the impact of these composite materials.
Fig. 07/ 08: Ventilation installations, Nyibaer
Fig. 09: Composite Rooflight, Varmahlíð Fig. 10: Rainwater goods, Varmahlíð
3. BENEFITS of building with Turf
3.1 Ease of construction
Despite the labour intensity, turf walls are generally easy to construct once you understand the key principles, (Fig. 11). HELGI Sigurdsson, master turf builder taught us how to extract and build with the following components:
Although we did not gain practical experience, through observation, we studied the remaining turf house components.
3.2 Limited Tools
Traditional buildings are made from limited turf components and require few tools, (Fig. 12). All turfs can be cut using a sickle and several types of spades as long as the sharpness of the blade is maintained. An experienced team can cut approximately 800 klambra per day; a modified rotavator can mechanically cut strenguar and torfa components and conserve manual labour.
3.3 Thermal properties
The organic composition of plant roots and soil provide excellent thermal properties to insulate against arctic temperatures. However, due to the absence of test data and the extreme wall thicknesses, the true thermal properties of turf wall construction are unknown.
3.4 Air tightness
The klambra is specifically cut and laid to an approximate angle of 60°. When a vertical load is imposed onto the klambra, the voids between the klambra are sealed providing an airtight wall construction, (Fig. 13). Chamfered turf joints can also be used at other areas of wall construction such as arch heads or wall ends where there is a vertical load to maintain structural integrity and air tightness.
3.5 Locally sourced
With an awareness of the biotic indicators, (Fig. 14) and understanding of the geological topography, appropriate turfs can be sourced locally at a relatively low cost. An extraction fee and transportation costs will occur if the source is not privately owned and mechanical machinery is required, (Fig. 15). The ground can quickly replenish once the turf is extracted, (Fig. 16).
3.6 Organic Material
Turf is an organic material and can be harvested and processed in a sustainable manor with a low embodied energy. There are no hazardous or toxic byproducts from the construction process and the material can easily be recycled; there are no waste products for all turfs can be buried within the internal wall construction or revert to its source.
Fig. 11: Typical wall build-up Fig. 12: Typical Tools
Fig. 13: Air tightness Details Fig. 14: Alchemilla Alpina
Fig. 15: Use of mechanical machinery Fig. 16: Extraction
4. Disadvantages of building WITH TURF
4.1 Width : Height ratio
Heligi explained that most turf buildings have a wall thickness of approximately 1.8m thick. There is not an exact calculation to determine the wall width to height ratio but through observations, repairs and rebuilding, Helgi’s has identified the approximate ratios.
Helgi states that he has not seen a turf wall higher than 7m tall. In rural Iceland with vast areas of landownership, land is not restricted to building with thick walls. However, due to the premium land value, building with turf using traditional techniques in urban environments is uneconomical, (Fig. 18).
Once the turf is extracted, it prohibits the use of the ground from pastoral and arable uses until the turf is replenished. If the average Icelandic house consumes approximately 1 acre of turf per build, it can be unappealing to sacrifice your produce for construction materials if your have a limited area of landownership.
Suitable turfs for construction are generally saturated and located in boggy ground, (Fig. 19). This results in the turfs becoming heavy which makes harvesting, transportation and building extremely labour intensive. Prior to agricultural machinery, turfs were stacked and dried before being transported by horseback although the turf is not as easy to use when dried.
4.3 Living Material
Turf buildings are living buildings constructed from organic matter and protected by living grass. Plant growth and grass cannot be restrained and must be regularly maintained to preserve the fabric of the building (Fig. 20). Roots can undermine the integrity of the structure whilst grass attracts grazing livestock that consume and trample on the wall heads and roof, (Fig. 21). Too long a period of drought and the grass can dieback, decomposing and causing further damage and allowing the exposed soil to be washed away by rainfall. To resolve this, several turf buildings have an integrated watering system to maintain soil moisture levels and preserve the grass.
4.4 Repairs & Maintenance
Due to the thickness of the construction and weight of the turf, walls are generally built as a course, made from two klambra, each facing in to the other with compacted infill between. The infill makes repairing sections difficult when trying to retrofit turfs into the structure without the internal mass falling out and losing its compression. It was demonstrated how a singular klambra could be cut to span the entire wall thickness. This method is time consuming and avoids the infill however the turfs are far larger and require at minimum team of two as the longer turfs are heavier and more prone to damage during extraction.
Fig. 18: Wall thickness Fig. 19: Boggy topography
Fig. 21: Unmaintained openings Fig. 20: Subsiding wall
5. COMMON Defects FOUND IN TURF BUILDINGS
5.1 Common Defects
There are regular occurring defects found within Iceland’s turf buildings. It is thought these could be addressed with a greater understanding of the material and considerate design and detailing.
Depending on the source of turf, its moisture content and volume of living matter, turf wall construction can shrink from 10-50%. It is crucial to source turf with a high clay content to help minimse these problems of shrinkage and settlement.
Due to the dampness and a lack of sufficient ventilation, numerous of the turf buildings that we visited that did not have modern interventions showed evidence of mould growth indicating that the decay was spreading outwards from the internal walls outwards. When we carefully dismantled the walls from buildings where the roof had collapsed, it was evident the turf with the greatest clay content had the greatest longevity, reiterating the importance of using clay-based turf.
5.4 Water ingress
The current turf house has evolved to the tradition aesthetic of the saw-tooth, timber gabled façade separated between valleys. All of the buildings we visited did not incorporate rainwater disposal systems and consequently allowed moisture to infiltrate down into the party walls.
This results in dampness and decay of the internal walls. Ideally, rainwater disposal measures would be introduced at these junctions, possibly a clay gutter similar to the Black House on the Isle of Harris or alternatively you could design out the need for valley junctions between gables.
5.5 Composite materials
Through inexperience and a lack of understanding of the behaviour of turf buildings, inappropriate repairs have been carried out of many of Iceland’s turf houses. A repair that is commonly found is the introduction of a synthetic membrane that is laid upon the roof to prevent water from penetrating the ceiling. The membrane lacks friction and requires the addition of a fish net to help secure the turf and allow roots to take hold. However, the addition of the net intensifies the load on the ridge beam causing the ridge to subside and the walls to spread.
An example of birch bark waterproofing was used on the reconstruction of the Norwegian log cabin (Fig. 26) but was not identified on any of Iceland’s turf buildings. Another common composition that causes greater damage is the introduction of metal stakes to enhance the stability of the construction. Each of the materials react differently to thermal fluctuations and result in greater deterioration of the wall. Metal ties were effectively installed in the Norwegian log cabin (Fig. 27).
Fig. 22: Shrinkage Fig. 23: Decomposition
Fig. 24: Water ingress at valleys Fig. 25: Composite materials
Fig. 26: Birch bark waterproofing Fig. 27: Composite ties
6. FURTHER RESEARCH
6.1 Further areas to research
To help resolve the common defects and bring new turf buildings up to current standards, there are a number of areas that could be investigated through test samples and monitoring to improve the performance of the construction.
6.2 Clay Mass
A clay mass could help control temperature fluctuations and regulate internal humidity through its hygroscopic properties. The appropriate location could be a rammed earth internal partition or a clay floor although this may not receive an appropriate solar gain from the low angled sun.
6.3 Thermal performance
Data is limited on the thermal performance of turf wall construction and therefore it would be beneficial to calculate the thermal resistance (K/W) and thermal transmittance (W/m2K) of typical turfs used. This would allow new turf walls to be economically built to current day standards, whilst minimising resources and labour.
6.4 Roof designs
A roof design with projecting eaves would sufficiently shed water away from the walls and minimise water ingress. This structure is likely to separate the walls from the roof and require composite materials and appropriate drainage provisions.
6.5 Wall stability
Freestanding turf walls remain unstable until the roof frame is erect and the turf roof binds with the walls. If you were to design with projecting eaves, it is likely the wall stability would be compromised. It would be beneficial to investigate if you could integrated turfs within a timber frame kit, whether you could use circular or arched bays to enhance the stability of the form or identify suitable composite materials that would help bind the building components together.
7. PERSONAL REFLECTION
This trip to Iceland has enhanced my observation that there seems to be a global stigmatisation towards building and living within earth buildings. However, like all natural materials, it is crucial to understand their behaviour, properties and limits to which they can be applied (Fig. 28) to avoid the recurring defects that deter occupants from their use.
As with all trades, it is important to listen to the tradesman using the tools because they have the greatest understanding of the material they specialise in, (Fig. 29). It is clear that Helgi is significantly experienced in turf building and that his observations and practical experience far outweigh the inexperienced bodies who dictate the inappropriate ways in which he should undertake repairs that consequently cause far greater damage in the long term. It would be desirable for him to document and record his knowledge as well as training others through hands-on learning; preferably by the creation of a national turf building organisation that could establish connections with EBUKI and other European partners that are looking at similar challenges in earth building and sustaining natural heritage.
Through the use of research, appropriate form and considerate detailing supported by a maintenance plan, there is still scope to design new turf buildings that are both beautiful and functional. There is the potential to build new houses from turf but the real opportunity that remains open are larger public buildings such as visitor centres, museums, hostel accommodation that can exhibit the turf building culture whilst absorbing the impact from tourists on the traditional turf buildings of greatest importance.
Despite the limited support and investment from the Icelandic government to sustain and preserve these cultural assets, it is clear that turf building still plays a significant part of Icelandic identity; this is reiterated through two installations (Fig. 30/31) that echo the pattern of the klambra at Keflavik airport.
Fig. 28: Limits to Turf Building Fig. 29: Education from the experienced
Fig. 30: Klambra installation 01 Fig. 31: Klambra Installation 02