Новый проект Ратоборцев — Городецкое гульбище. Август 1621

Today we’ll speak about heat insulation of Pavel’s log house. Only good caulking could insure it.

Caulking is the processe of sealing joints or seams, or closing up gaps in various structures. Any log house has some gaps between rows of beams. While they are getting dry the gaps enlarge unevenly.

Modern carpenters recommend to caulk twice. First time during building process, second time — in about 8–12 months, when the house gives the maximum shrinkage. One should caulk all the walls at once, in order to avoid warping of the framework. Nowadays for caulking they use:

  • oakum;
  • flax-jute fiber;
  • basalt fiber;
  • polyurethane foam;
  • mineral wool.

They use caulking irons of different width and with different blades. A qualified modern team caulks an average log house in a couple of days, achieving very good thermal insulation. And what about the Middle Ages?

Of course, caulking was quite different. Firstly, there was another insulator. Flax oakum was too expensive material, it was used for textile production. There was no jute because there were no contacts between Ancient Russia and Ancient Bangladesh. So, they used moss — a widespread material in our latitudes. Secondly, the caulking technology was different. We know from archaeology that there were different approaches to this question, depending on the purpose of a building and the social status of its owner. There are homesteads with a very neat jointing and temporary or very poor huts, put up and caulked «crudely». In the forest-steppe zone joints generally were insulated with clay. Remains of such coating sometimes allow to determine the height of the walls. There were many reasons why some huts were built rather poor. For example it could be a temporary winter hut for a military or commercial unit, or a jerry building for homeless victims of a fire.

So, not all dwellings of early Middle Ages fit our ideas of «good old architects». Many of these dwellings would make a modern carpenter contemptuously twisting his mouth.

Our personal experience in the reconstruction of wooden buildings gave a lot of interesting practical knowledge and skills. For me, the most enjoyable was the work with the moss. Moss has a whole list of advantages over modern materials. Firstly, moss is environmentally friendly natural material that has even healing properties. Secondly, moss withstands extreme temperatures and drying: it can absorb moisture and does not rot (as distinct from oakum).

Thirdly, moss has tonic and anti-microbial properties, as well as high activity of antibiotics. Moss produces lichen acids, widely used in medicine against streptococcus, staphylococcus, tubercle bacillus, pathogens of dermatitis.

It’s important to use only moistened moss for caulking. During natural shrinkage of a log house moss becomes homogeneous mass, filling all cracks and cavities.In this case there will be no necessity of additional caulking.

It’s also important to use right tools. Using a caulking tool of a material more durable than the wall, one will find that this tool inevitably damages the surface, making chips and dents. Very handy is a soft pine caulking tool, and it can be easily replaced if damaged.

Pavel’s farmstead was built according to a legend: «for homeless victims of a fire», so the primary caulking had not been completed by the start of the project. In addition, the log house shrinked unpredictably because of uneven heating. It brought a lot of trouble, Pavel had to caulk new cavities. Pavel has finished caulking his dwelling and decided not to get himself in caulking the stable and barn. It’s not a difficult, but a very time consuming activity. As a real medieval peasant Pavel ensured minimum convenience and focused on other, more important things.

Pavel’s fellow re-enactors decided to help him to caulk exterior walls of the house during the open day. Our hero, like a real village grandpa, gave his grandsons some home brew and rebuke for their inefficiency. And sent them to collect firewood instead of caulking.