Topic: Historical and Modern Housebuilding
Read the peer's work with the following starting points:

How can the peer's summary be further developed in terms of the description of:
 The content of the sources
 The critical evaluation of the sources
 The description of how the sources relate to each other.
How could the selection of sources be developed in a future degree project?
The peer's work: "University of Gothenburg Alexander Johansson KBB320
Synthesis of knowledge
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How are our historic stone houses built and what problems do stone structures face today?
I have been trying to read up on natural stone masonry, and in particular trying to find examples of constructions where both natural stone and brick have been used in the same construction. The overwhelming majority of our historic buildings are in stone, and not infrequently they have, if not entire walls of natural stone, then at least elements of natural stone.
The focus of this compilation has been to read about a wide range of topics in the field of natural stone masonry, but perhaps the most focus has been on craft processes and descriptions of approaches to the material.
Which stone is used where varies greatly from place to place, so the magnifying glass has also ended up reading about the difference in materials across the country, as well as the problems we face in the conservation and restoration of natural stone structures today.
Natural stone is a material that has historically been used in Sweden since before the advent of bricks. Our early stone buildings were built by cold masonry where stones were stacked on top of each other without the use of mortar or other binders.
However, natural stone has had difficulty asserting itself in buildings outside of high-rise buildings such as churches, manor houses and mansions, partly because of the ingrained tradition of building residential buildings in wood, but also because it was an expensive material, both in terms of transportation if the material was not close at hand, but also in terms of processing.
In 1766, at a time when there was a shortage of wood for building houses, and even a promise of a 20-year tax exemption if you built your house in stone, Carl Wijnblad writes about how natural stone was difficult to handle and unsuitable for building houses. Here, however, he is talking about natural stone in the form of gray stone, a collective term for blocks of stone picked directly from the ground or dug up, for example, during agricultural work, and not about the brick, which he warmly advocated in his book Beskrifning, huru allmogens buildings, so of stone, as well as trees, must be erected with the greatest economy, according to attached project drawings in six copper pieces, as well as proposals for necessary building materials. He found the stone unsuitable as it requires a lot of processing and a lot of lime to be good enough to be used other than for foundation walls and cellars. The stone was also considered to be damp and cold, and suitable only for animal houses.
Buildings made of both natural stone, in the form of grey stone, and brick in the same construction are described in a number of different designs in the training material from Hermods in the document Byggnadskonstruktionslära (för murare) : undervisning per korrespondens (1907). In the chapter Walls of stone blocks: "Such walls of stone blocks, which are to have any appreciable height, are, however, erected as mixed walls, i.e. they are erected with horizontal bands and vertical columns of brick". This also clarifies several other
approaches to the inclusion of bricks in natural stone walls, with bricks or more tumbled stones being used in virtually all parts of the wall where greater precision is required. Window surrounds, the corners of the wall, the above-mentioned stabilizing shifts, and even roof ends should be made of brick. Hermod's text is relatively exhaustive in the field of natural stone masonry, and describes various approaches to stones in differently worked conditions, but no information about who or where these experiences and approaches come from is given in the text. The text is familiarly signed by Hermods himself, but it is doubtful that he is the author.
Further reading in, for example, Arvid Henström's book Landtbyggnadskonsten volume 5 (1869) offers a slightly more detailed account of the building method, but in general the advice sounds the same as in Hermod's text. As an engineer, Henström should be well versed in the art of building, and his recommendations are sound, even if the text itself is not significantly exhaustive in terms of illustrations or other aids other than a running text description of different approaches to masonry with natural stone.
The fact that someone like Henström is giving the same advice as Hermods gives good credit to the fact that the information in the training material is sound and well based on literature in the field.
However, Henström makes it clear already in the introduction to this text that it is not written for the experienced craftsman, but "it is intended for the farmer and his inexperienced workers who are unfamiliar with building details and their form and execution", which explains the lack of drawing examples and more detailed descriptions of the craft processes. Both texts recommend the use of the best quality hydraulic lime mortar for masonry.
One conclusion to be drawn from reading both Hermod's and Henström's texts is that the construction of a stone wall does not differ so dramatically, whether it is built of brick or natural stone. The goal is to achieve a joint where the different building blocks interact with each other to create a stable structure that can withstand forces from different directions, but different solutions need to be applied depending on how processed the stones are. Both provide insight into the role that brick can play in natural stone construction, and are described as the rational choice in many cases. Neither text is exhaustive, or should be seen as detailed descriptions of craft processes, but they can be used, with a little prior knowledge, as a complement to the execution of masonry with natural stone.
Structures using relatively unprocessed natural stone face a number of problems in addition to those encountered during construction.
The Geological Society London publishes a journal that compiles information and articles in the field. The journal itself is locked behind fees, but the introduction was available for guidance to other authors in the field. The introduction is written by Professor of Geology Siegesmund Siegfried, who in his text highlights the problems faced in the preservation and restoration of natural stone buildings. Strategies on how to deal with damage caused by natural degradation of the stone, how the environment influences the grading, how anthropogenic circumstances accelerate decay, attack by algae or microorganisms in the stone.
The reading of Siegesmund's text therefore led me on a trail of other texts in the field, and eventually to the article Impact of the surface roughness of stones used in historical buildings on biodeterioration, a text on how the surface texture porosity of building stones influences the speed and degree of biological impact and degradation.

Biological impact refers to plants, both clinging plants with roots and creeping plants such as lichens and mosses, and their impact on the structure of the stone, both as living and dead material. The material is based on investigations carried out in Nigde, Turkey, which is somewhat different from conditions in Sweden, but the different types of rocks investigated are similar to those used in Sweden, such as large amounts of limestone. The source is really only tangentially relevant to this compilation, but interesting reading nonetheless, and definitely a recurring topic in the question of how our stone houses should be taken care of.
Sources
● Henström, Arvid (1869) Practical handbook in the art of rural construction: including the study of building materials, the processing and joining of building materials, the shape, dimensions and strength of building components .... Örebro: Beijer
● Hermods (1907) Teaching and correspondence, Building construction for bricklayers, seventh letter.
● Mustafa Korkanç, Ahmet Savran (2015) Impact of the surface roughness of stones used in historical buildings on biodeterioration.
● Wijnbladh, Carl (1766). Description of how the common people's buildings, both of stone and wood, may be erected with the greatest economy, according to attached

project drawings in six copper pieces, and proposals for necessary building materials. Utgifwen på kongl. maj:ts allernådigste befehlung, efter föregångit gillande wid riks-dagen år 1765, af Carl Wijnblad. Stockholm, printed by Peter Heszelberg, 1766. Stockholm: (Hesselberg!