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Building a reed-roofed section for a Stone Age row house

Date: 
Monday, 7 May, 2012 to Wednesday, 25 July, 2012
Responsible: 
Reino Juutinen
Antti Palmroos
Siim Sooster
Number of Participants / Visitors / Audience: 
800

Notes from a project in Kierikki in summer 2012 – Building a reed-roofed section for a Stone Age row house.

The project started at the beginning of May 2012. Construction plans for the new house were originally based on the information from the archaeological excavations in Korvala, Yli-Ii (Schultz 1999). Later Rauno Vaara put the results in practice by drawing the initial plans and taking part in building a Stone Age row house at the Kierikki Stone Age Center. These house models were in turn modified by Sami Viljanmaa.

It was obvious from the beginning that we needed to compromise and/or tolerate a few inconsistencies in order to guarantee the safety of the employees and tourists. In this report I will try to clarify the reasons for our choices and working methods.

Working and methods

The foundation

The first phase was to cut down the necessary amount of timber and to debark the trees with traditional woodworking hand tools, drawknives. Pine (pinus sylvestris) was chosen as the wood for the building due to its major role among the timber materials used in the area in the Stone Age (i.e. excavations in Purkajasuo 1995–2004). In addition, pine has always been used in log structures in Finland for its suitable properties and good preservation.

The bark came off easily as the wood was fresh. Larger logs were rather heavy and difficult to maneuver but, once the bark was removed, most of the moisture evaporated in a few days and thus the logs became lighter and easier to manage.

The foundation (rough gravel) for the new house was brought to the shore May 28. In this phase we chose to build directly on top of the gravel. Later on very fine crushed gravel would be brought to the site for “floor surface”. Some sand would also be brought and piled outside to make the hut look like it was dug to the depth of about one metre below ground level. The idea for using very fine-crushed gravel was sprang from the replacement of some parts of our wooden pathway with this material in 2010. As it made the village accessible for visitors who use wheelchairs and pushchairs, the solution was considered very functional. In addition, the new pathways were less disturbing in appearance than the wooden pathways. The new pathways also require significantly less maintenance work.

So, after the foundation was laid and the timber was prepared, the construction of the first tier of logs began on Tuesday May 29 (see Picture 1). The coping notches were carved with a chain saw (see Picture 2), and all the joints and corners were strengthened with pikes of steel. The use of steel was not necessary for the structures to remain in place but this action was only a precaution to guarantee the safety of the visitors later on.

Because there were only two craftsmen working on this project at the time (alongside with their other tasks), we decided to use all the modern tools available (such as a chainsaw, a power drill, a metal hammer and a saw) in order to ensure the completion of the construction. This is justified by the fact that earlier in May archaeological experiments were carried out in Kierikki in which stone, bone, or antler tools were used in cutting and preparing timber. The amount of time consumed in the woodwork with Stone Age methods could be estimated and then compared with the modern techniques as follows.

All three tiers of logs had 40 notches altogether which would have taken over 30 hours to carve in total (according to the project results of working with logs 19–24 cm in diameter). To this number we need to add the hours consumed by the cutting of the timber (at least 32 cuttings) that would have taken an estimated 45 hours. To this number we also need to add the hours used in debarking all the timber (appr. 124 m). This phase would have taken nearly 21 hours. As a result, we get an estimated time needed to prepare the timber and build a foundation three tiers of logs high and 6x8 meter wide for a Stone Age house. The total time consumed was 96 hours of continuous work. To this number we must naturally add the amount of time that was needed to fix and maintain the tools in use as well as carrying, moving and handling the logs. What is more, it must be taken into consideration that handling logs this size requires at least two persons at all times. (For more detailed information on Stone Age wood working, see attached file)

The roof constructions

On Monday 4 June began the building of the roof constructions. First, we needed to erect the two main poles. About 80 cm of the bottom ends of these poles were charred (see Picture 3). The method of charring was originally based on the information from excavations, and the results from the previous demolishing report suggest that this method served the preservation of the timber (see previous report “Notes concerning the demolishing… etc.”) After the poles were erected, we carved the upper ends and lifted the ridge beam on top (with help of a tractor and a grab, see Picture 4). Secondly, we added 10 more rafters to the corners and both sides (see Picture 5). After this we built the base structures for the small porches in practically the same way. As has already been established, all the joints were strengthened with steel pikes, even though these means were not necessary for merely architectural reasons.

On Friday 8 June we started to place horizontal poles to the roof. All the poles were supported by pegs of wood which were drilled and hammered to their places. The distance between the poles was 35 cm. This number was determined by both the length of the reed we were about to use and the fact that we wanted the thickness of the roof to be 30 cm. On 20 June the roof structures were ready (see Picture 6) and we could start the preparations for the next phase. However, some more scaffolding was still to be made (see Picture 7). With this sort of solution the first row of reed was easy to lay, and the eaves of the roof would stay still throughout the whole project.

The roof

The reed we used was collected from Hiidenmaa, Estonia. The same plant (Common reed, Phragmites australis) grows widely in Finland, and also in our latitudes in Yli-Ii. We have clear evidence that reed has grown in these parts of Finland already in the later Stone Age, when the climate was even 2–3 ˚C degrees warmer than today. Because reed is not professionally collected or sold in Finland, we were obliged to order it from Estonia. Besides the reed, from Estonia came the roofer master Siim Sooster, who stayed in Finland from 27 June till 4 July, and taught us how to work with the material.

The bundles of reed were placed next to each other beginning from the center (see Picture 8). Thicker and shorter reed was used in the middle and thinner and longer bundles were spared for the corners. (The longest bundles were all spared for the ridge.) The reed in the middle was placed exactly vertical, but the angle kept growing all the way towards the corners.

After the bottom row was laid, sliced rod of spruce (Picea abies) was placed on top of the row and tied still with fresh birch withes. In this phase we needed to make sure that the layer of reed was equally thick everywhere. By pressing it heavily with our hands we were able to move the reed sideways (see Picture 9). One withe was tied around both the horizontal pole and the sliced rod, at about every one meter, but not yet tightened (see Picture 10). After one row was ready or the reed had been placed and leveled at least from the length of 4–5 metres, the withes were tightened by pressing down the rod and pulling the withe at the same time. The thicker end of the withe was then twisted over itself and pushed under the rod. As the withe dries properly, the binding knot will strengthen even more. When working with the withes, one must take care not to let them dry for more than 30 minutes before tightening the knot.

The second row of reed was laid at the same level with the bottom row (see Picture 11) but it was tied to the second horizontal pole and yet another sliced rod. (To make sure that the eaves would stay still, alongside with the sliced rod and withes, we also used steel and iron wire.) Part of the reed was then hammered upwards with a special tool called a stomping board. With this action we determined the thickness of the roof and simultaneously formed the first part of actual roof surface.
The bundles of reed for the third row were then placed above the second row. The bottom line of the new row was measured about 15 cm below the second sliced rod. The rod obviously had to stay hidden under the reed. When there were enough bundles next to each other, we tied them still with yet another sliced rod and withes. After this we again hammered the reed upwards to form some more roof surface. This way, row by row, we circled the house until the desired height was reached.

What is more, some thatching needed to be done from inside. After the outside of each row was completed, we had to go in and patch the roof with very small bundles of reed. This way, when it still was possible, we were able to fill all the holes and hide the dry inflorescences that later could easily catch fire (see picture 12).

When we had finally reached the desired height, the top ends of the reed were turned over the ridge beam – and in this case tied still with steel and iron wire. The top ends of the reed from the other hip of the roof were then cut off and we could move to the next phase.

The ridge

Building the ridge started by placing bundles of long reed sideways on top of each other, thicker ends towards the eaves. The first pair of ridgepoles was placed directly on top of the actual ridge and tied still. By pushing the reed upwards heavily, we were able to level it. By pushing the ridgepoles upwards simultaneously, we were able to adjust the angle of the ridge. After setting two more pairs of ridgepoles, we tied the third pair still and went on with another band of reed. This way, every other pair of ridgepoles was tied whereas every other was not (see Picture 13). The work continued until we reached the other end of the house. The last phase was to thatch the ridge (see Picture 14) and level the eaves by hammering them with the stomping board. The ridge was completed 20 July.

Images

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picture 13
picture 14