Buried cities, a professional's view

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

The theory of the construction of foundations for two-story houses with a wooden second residential floor above a stone basement in the period from the late 18th to the early 19th centuries

author: Monin Ilya Alekseevich, Ph. D.

The purpose of this article is to determine the feasibility of building basements buried in the ground in private low-rise construction in the pre-industrial era. So, for consideration, the criteria of the Construction price, the durability of the structure, the ease of operation of the structure and the technological feasibility of the project will be used.

As a result, we must determine the feasibility of building a two-story private house with a basement buried in the ground or without a basement.

Let's start with a description of the materials available in the construction of the 18-19th centuries.

In the period under review, the following building materials existed: hewn (chipped) or wild cobblestones, fired clay bricks, lime mortar for brick and masonry, logs and sawn timber.

Reinforced concrete strong structures did not exist at that time due to the lack of fast-hardening Portland cements and steel rolling rebar. Also, there were no polymer materials for waterproofing.

For one-story residential construction, wood was used almost exclusively, namely: in the form of logs for walls and sawn boards for floors and roofs. Wood has a better thermal insulation capacity and a lower volumetric heat capacity than brick and even more wild stone. Thus, with severe frosts outside and with cyclic stove heating, it was much more comfortable to live in wooden houses than in stone ones.

The choice of wood for one-story construction is also determined by its greater availability in central Russia than brick and stone. In treeless regions of the country, the most accessible materials were chosen as a building material for one-story peasant housing: stone in mountainous regions, straw and clay in the steppes (huts).

For a well-to-do house in the city, a two-story building system was used. So the first stone floor played the role of a solid pedestal, and already on it, on the second floor, a wooden house was built, in which people with stove heating already lived. At the same time, the basement stone floor was not heated, but served as a cold room for warehouses and other household needs.

How was the first stone floor built in the city?

Based on the materials available and the simplest building technologies of that time, the procedure for the construction of the first basement floor was as follows (see Figure 1.a):

- digging a trench under the future bearing walls of the stone basement to the depth of freezing of the soil, while the excavated soil is carried inside the perimeter of the future house, thereby raising the floor level in the basement above the level of the surrounding ground;

- filling the excavated trench with broken natural stone of various fractions to the ground level (the stone does not shrink and does not crumble from high-cycle freezing-thawing);

- laying out a basement belt of hewn stone blocks from ground level to the level of the poured snow cover in winter (for Moscow in the 18-19 centuries, rolled snow on the streets raised the street level in winter to a height of 50-70 cm from the summer dry soil), while the hewn stone acted as a waterproofing of the overlying brick walls from the absorption of flood waters;

- erection of brick walls on a lime mortar base from hewn stone.

Fig. 1. Sectional view of a two-storey building with a stone first floor-basement and a second wooden floor: a) The true location of the basement relative to the ground at the time of construction, b) the location of the basement relative to the ground after the Abnormal "Ground Flood".

1. Foundation trench with broken stone backing.

2. Belt of hewn stone plinth.

3. Brick wall in the basement.

4. Window in the brick wall of the basement.

5. Wooden 2nd floor.

6. Ground level at the time of construction of the building.

7. Backfilling the basement floors with soil removed from the foundation trench.

8. Steps to the basement door from ground level to the "Ground Flood".

9. Door in the brick wall of the basement.

10. Steps of descent into the pit to the door of the backfilled basement floor.

11. The level of the street soil after the "Ground Flood".

12. Pit by the window in the wall of the basement after the "Soil Flood".

13. Cobblestone pavement at the time of construction of the house before the "Ground Flood".

The use of fired clay bricks in construction is more convenient and cheaper than building entirely from hewn stone. But the use of natural stone in backfilling foundation trenches and in a stone hewn basement belt is mandatory, since wild stone is resistant to numerous "wet-freeze-thaw" cycles, while porous brick collapses very quickly in a zone of constant moisture and frequent freezing at the ground surface. …

Above the built wall of the basement floor, a ceiling is made from powerful wooden beams with a flooring of thick floorboards, or a brick (stone) vault is made, which makes it possible to install stone solid floors in the upper floor.

Now, as proof by contradiction, let's try to mentally build a one-story house with a basement buried in the ground. So we will have the following rise in prices and additional difficulties:

- In the process of construction, we will need a much larger volume of earthworks, since we need to dig out the soil from the entire volume of the basement;

- All the soil taken out from under the building must be removed somewhere, and this is an additional significant cost;

- It is necessary to additionally tear off the pit around the house, for the installation of masonry walls below ground level (brick in the laying of walls in the ground is unacceptable);

- tearing off a trench for a stone backfill of the foundation under the basement walls (deepening the basement walls into the ground does not negate the construction of foundation trenches with a stone, since the depth of soil freezing in a cold basement practically does not change);

- The wall in the soil needs to be made thicker, since it must withstand the pressure of the soil layer from the outside;

- Backfilling of basement stone walls from the outside after the end of their construction;

- in the basement floor, it is necessary to arrange pits for collecting groundwater oozing from the stone walls, and the water flowing into the pits must be periodically scooped out manually with buckets and taken out into the street into the gutters.

Thus, when we try to bury the basement in the ground, we do not get any positive results, but the construction costs increase greatly, as well as problems with further operation of the basements buried in the ground increase.

As for modern basements, their construction is associated with fundamentally different possibilities of the modern construction industry.

1. An open modern basement does not require additional foundation trenches filled with stone, since the basement is heated all winter by heating systems passing through it and the soil freezing zone is outside the basement slab.

2. The basement is not torn off manually, but by high-performance excavators with soil removal on powerful trucks. At the same time, the volume of the foundation is much less than the volume of a multi-storey building above it, and the cost of removing additional soil is not significant in total costs.

3. In modern basements, the walls are made of reinforced concrete with external polymer-bitumen waterproofing, and possible water seepage is pumped out of the pits by automatic electric pumps, and not manually.

4. A modern basement does not have to be at full height of a person, but the entire volume of the basement is needed for laying modern engineering networks: heating, water supply, sewerage, electrical network, communication networks.

In suburban low-rise construction and in our time, the arrangement of basements is ineffective and very costly. So the foundationless construction of low-rise private stone houses on an insulated reinforced concrete slab with a depth of immersion in the ground of about 20-30 cm became widespread. And for light wooden houses, screw piles made of steel pipes are used as a foundation, which are screwed into the ground to a freezing depth along the perimeter of the walls with a step of one or two meters, thereby generally saving the developer from carrying out earthworks.

Why then did they make basements buried in the ground and why are there so many basements and semi-basements with windows below ground level in old houses?

It is impossible to explain from the point of view of engineering common sense the huge number of basements and windows below ground level in old stone houses over 200 years old. At the same time, the deepening of buildings due to subsidence of foundations and due to the formation of a "cultural layer" in cities is not an explanation, since much larger buildings with an age of 100-150 years do not have any subsidence of the foundation and the cultural layer has not grown in any way over the last 100 -150 years, which can be clearly seen from the available photographs of these buildings over the past 150 years of their standing.

Abnormally filled-in brick basements are noted in buildings earlier than the first third of the 19th century. That is, in the period of the first third of the 19th century, a kind of global cataclysm occurred, which led to a very rapid and intensive "flooding" of cities with soil. Moreover, the cities were covered with soil in such volumes and at such a speed that they did not have time to remove the soil from the streets, and the stone pavements at that time sank in deep mud irrevocably. When the level of filling the street with soil began to approach the windows of the first floors of houses, these windows were fenced off from the soil with protective brick walls (pits) or walled up altogether.

In the light of all of the above, the Sytin House (Sytinsky per., Building 5, Moscow) turns out to be a very valuable artifact of that "Antediluvian" era, since the exact dates of its construction (1804-1806) are known. When viewed from the courtyard, the existing artificially created pit is still visible, pushing the soil available in the courtyard away from the originally overground walls of the basement brick floor (see photo 2). From the street, the basement of Sytin's house has not been excavated at all (see photo 1.), since the only window visible on the facade of the basement floor protrudes above the sidewalk only by a small segment of the round top of the window. At the same time, in the visible part of the window, a full-fledged wooden frame with the remnant of glazing has been preserved, and the soil poured on the street is piled directly onto the frame and the glass in it. The rest of the lower rectangular windows on the street side of the basement floor are bricked up tightly with brick, which can be seen when examining the basement from the inside.

Photo 1: View of Sytin's house from the street.

Photo 2. View of Sytin's house from the courtyard to the pit, dug out at the courtyard facade to the stone basement belt. I do not know the time of the excavation in the courtyard, but due to the appearance of the white stone in the retaining wall, its construction probably dates back to the middle of the 19th century.

The true level of the ground at the time of construction from the side of the courtyard most likely cannot be determined, since the courtyards in those days were not paved with stones, but sprinkled with sand or rubble on the paths. But from the side of the street, there is a great chance to find a cobblestone pavement or wooden sidewalk flooring corresponding to the ground level at the time of construction of the house.

To find the old pavement, it is not necessary to dig out the entire house around the perimeter, but it is enough to carry out a small excavation in the area of the central vaulted window to the level of the beginning of the stone part of the foundation.

Arrangement of this excavation to the level of the old pavement will visually make sure of the presence of an abnormally thick layer of soil "flooding" of the street, as well as show the true view of a city house with a full-size high stone first floor and without "mythical" cellars with windows to the ground.