Houses made of earth, like any other buildings, must have a good roof, strong walls and a reliable foundation. (What else does the house need to avoid getting old before its time?). When constructing the earth buildings, the choice of design elements of the house should take into account the peculiarity of the material.
Foundations and walls lower zone. Usually earth walls are built on strip foundations, which are a wall buried in the ground and rising above the ground surface by 0.2-0.5 m. An example of such a foundation is shown in Figure 6.1. The strip foundations can be made of rubble stone, rubble concrete, concrete or reinforced concrete.
The depth of the foundation is taken as for standard stone buildings, based on the type of soil on which the building is built, the depth of seasonal freezing, the ground water level and soil humidity.
For rocky soils, the foundation can be laid directly on the surface, for large-block soils, as well as for gravelly, large and medium-sized sands - at a depth of at least 50 cm.
For fine and powdery sands, as well as for sandy loam, the depth of the foundation is set regardless of depth of soil freezing only if the ground water lies below the depth of freezing by 2 meters. In this case, the foundations should be laid to a depth of at least 70 cm. For higher ground water levels, as well as for loams and clays, the depth of the foundation should be less than the freezing depth.
The starting criterion for selecting the freezing depth is the standard depth of seasonal freezing. If the building is not be heated during the winter period of the year, then the depth of soil freezing is recommended to be taken 10% more than the standard.
For heated buildings at a temperature of +15°C, the freezing depth can be assumed to be 20% less than the standard freezing depth if there is no basement and 40 % less if there is a basement in the building.
The walls of the strip foundations should be covered with bituminous -mastic and isolated from freezing with the ground roofing material, film or other material.
The strip foundations are recommended to be laid on a compacted filter pad made of sand (except fine and dusty), small crushed stone, boiler slag and other non-porous materials.
The lower wall belt (plinth) is usually made of concrete, brick or stone to protect the lower part of the wall from rain splashes and mechanical damage. The wall base must be at least 500 mm high (usually 500-700 mm) and at least as wide as the wall width.
The waterproof layer and pavement. The waterproofing is recommended to arrange on two levels: the foundation and the top of the plinth.
Before the waterproofing, the top of the foundation and base should be leveled, if necessary, using a 1:3 or 1:4 cement-sand solution.
The waterproofing layer is made over a dried leveling layer of two or three layers of roofing material over bituminous mastic: the top of the foundation or basement is covered with mastic and the first layer of roofing material is glued onto it, which is again covered with mastic, and the second layer of roofing material is glued. The edges of the roofing material should be put on the walls on both sides by 30-50 mm.
Additional protection for the base of the wall is a blind area along it.
The blind area is a ground-level structure in the form of a path with a slope from the wall and serves to protect the foundations from surface water and divert water from the walls and foundation that flows from the roof. The blind area should extend 20-30 cm beyond the edge of the roof, have a slope of 1:10 away from the building and be located at least 20 cm below the waterproofing layer on the base.
In addition to performing the functions of a blind area to drain water from the wall, it looks good in combination with whitewashed walls and a decorative and protective base, which gives a special beauty to an earth cottage.
Walls. The construction of the solid masonry wall made of solid soil blocks is shown in the Figure below.
For exterior walls, the thickness should be determined depending on the design temperature of the area. At the same time, the thickness of the external walls of two-story buildings for the first floor should be at least 50 cm, and for the second floor - at least 40 cm. For single-story buildings, the minimum thickness of the exterior walls is 40 cm. Internal load-bearing walls on the first floor of two-story buildings must be at least 40 cm, while on the second floor of two-story buildings and in single-story buildings-at least 25 cm.
The width of the wall of unstable blocks between the windows should be at least 100 cm, and the distance from the corner of the building to the window should be 150 cm. Narrower piers can only be made of stabilized soil blocks or other materials of increased strength.
The masonry walls should be made of air-dry soil blocks on solutions of semi-rigid consistency with ligation of seams. Thickness of the seams should be minimal and not exceed 10 mm for horizontal and 15 mm for vertical. The height of walls, as well as window and door openings should be increased against the design dimensions by the amount of the expected precipitation, assumed to be equal to 3-4 %.
Sometimes the outer corners are made of stone or brick to protect against damage. For the same purpose, you can build walls with rounded or beveled corners.
To stiffen the masonry, it is recommended to lay annealed wire with a diameter of 2-2. 5 mm in 1-2 rows along the perimeter of the wall every 3-4 rows of blocks.
At the level of the attic floor along the entire perimeter of the load-bearing walls, it is recommended to arrange a connecting belt of 3-4 rows of ceramic brick masonry. Waterproofing from two layers of roofing material should be arranged at the top of the connecting belt.
Construction of the soil blocks is carried out before the onset of autumn and winter frosts. The masonry in summer is performed on a clay solution, and in spring and autumn - on lime and mixed solutions.
In the process of erecting walls, especially from unstabilized soil blocks, measures to protect them from atmospheric precipitation must be taken.
Roof. The roof that hangs over the walls is a distinctive feature of houses made of earth. Wide eaves hanging from all sides to throw water away from the walls, hipped roofs, especially on single-story buildings, are a good protection of earth walls from precipitation. The width of the eaves overhangs (take-out) is recommended to make at least 60 cm.
Drainage devices. Wide hanging roof does not preclude the use of protrusions and teardrops to prevent water from falling on the walls. Drainage devices should not only throw water away from the wall, but also prevent water from accumulating on them and further seeping through the joints to the lower part of the wall. Drainage devices are best made of galvanized steel. They should be installed first of all where the ground connects with other material, especially over the lintels of windows, when the connections between the lintel and the ground do not have protection in the form of plaster. Drain pipes I and other devices must be made so that the water that flows from them does not come into contact with the wall.
Windows and doors. Normally, window openings are covered with -wooden or reinforced concrete lintels, which should have wide support surfaces from 0.5 to 1 m on the walls on each side. Window lintels should cover the entire width of the wall. Wooden lintels are usually made of boards or bars 10-12 cm thickness. The ends of wooden lintels should be wrapped with tar or roofing material, or covered with bitumen. Wooden elements (window and door frames) from the outside, in contact with the walls, are covered with bitumen or upholstered in 2-3 layers of roofing. Window and door frames are attached to wooden antiseptic plugs laid in the walls every 5-8 rows of masonry.
Between the boxes and lintels, leave a gap of 3-4% of the height of the opening on the wall draft, which is laid with a heat-insulating material.
At the bottom of door and window openings, one or two layers of roofing or roofing material are laid so that the ends of the insulation material go under the piers by at least 15 cm. Tin drains are installed at the bottom of window openings for water runoff.
It is better to install door and window frames on the outside of the walls, since in this case the lintels are less susceptible to raindrops and rain dust, and there is no need for wide drainage devices (teardrops and aprons). In addition, the windows located on the outside of the wall have the advantage of forming wide sills and lintels, which, when slanted, reflect light inside and have a pleasant appearance.
Floors. The same requirements apply to the construction of floors in the buildings made of earth as for standard brick construction. The lower (or, as it is sometimes called, false) floor can be made suspended or monolithic. When constructing a monolithic floor, it is important to provide a continuous waterproofing membrane of some kind connected to the waterproofing layer in the wall. Wood surfaces should be protected from dry rot; wood should be treated with a preservative agent and the edges of beams should be isolated from contact with possible sources of dampness.
Ceiling beams and ceilings. Ceilings are made of wood or precast concrete. The wooden beams are laid on a wooden distribution harness and connected to it with a nagel or cut-in. Iron-concrete beams are laid on a reinforced concrete distribution harness, which is supported by a belt of concrete or brickwork 12-14 cm thick. Beams harnesses are connected by welding, bolts or clamps.
In one-story houses with floors on the ground, only attic floors are arranged, and in the presence of a basement or underground, also basement floors. The span of wooden beams (the distance between the supports) should not exceed 4.5 m.
The distance between the beams in the basement floors, when the floor of boards is arranged directly on the beams, should not exceed 0.5 m. In the attic floor, the distance between the beams should not exceed 1 m.
The thickness of the beams for basement and attic floors must be at least 1/24 of its length. The ends of the beams are laid in nests left in the upper belts, and if there is a basement or underground, in the lower connecting belts made of ceramic bricks. The ends of the beams should be placed at least 150 mm long, the depth of the nests should be 200-250 mm. The ends of the beams are antisepted to a length of 750 mm, tarred to 200 mm and wrapped with tar coating around the entire perimeter, and then placed in the nest so that they do not reach the back wall of the nest by 30-50 mm. After laying the beam, its side and upper sides are sealed with a solution.
Between the extreme beams and the wall should be a gap of at least 50 mm, which is sealed with a rail. A strip of roofing or roofing material should be put between the rail and the beam.
Overlappings should be carried out on wooden beams with filling of rolling boards or filing boards along the bottom of the beams when using light insulation (mineral wool, etc.). Roll-up boards are laid on 40x40 mm or 50x50 mm bars nailed to the bottom of the beam.
Insulation that is placed between the floor beams should be protected from moisture. For this purpose, a plastic film should be placed on the roll-up boards under the insulation. The exposed surface of the insulation should be protected with a layer of clay, lime or cement mortar.
Fuel or granulated blast furnace slag, expanded clay gravel, mineral wool slabs, etc. are used as insulation.
Rafters, purlins and roof covering. When selecting a roof structure, it is important that there are no spacers on the walls. The supporting part of the roof (rafters) is arranged of wood.
The lower ends of the rafters must be laid on the outer walls through a lining in the form of a longitudinal board or bar (rafter plate). To connect the external walls with the rafters, they are attached by means of wire clamps to metal hooks embedded in the wall thickness 25-30 cm below the rafter plate.
The inclined rafters running the crate, which are having a flat roof of cement, asbestos cement sheets (slate), corrugated asbestos-cement sheets, galvanized steel roofing, tiles, roofing materials (roofing felt, asbestos felt), etc.
Eaves roof overhangs should be formed by releasing the truss legs outside the outer face of the wall or nailing short boards to the rafters. At the same time the rods make a continuous sheathing of boards.
Partitions. The partitions can be constructed, like the main walls, from soil blocks. In places where the partitions are adjacent to the load-bearing walls, a groove 4-5 cm deep is arranged. Flexible anchors made of wire twist are used to connect walls and partitions that have different sediments (made of different materials, erected at different times, separated by sedimentary seams, etc.).
It is recommended to lay out partitions from ground blocks with a thickness of 1/2 or 1/4 blocks. With a partition length of up to 3 m and a room height of no more than 2.7 m, the partition thickness can be 1/4 block, with a larger length and height — 1/2 block.
The partitions should be installed on the foundation, which must be made in accordance with the requirements for foundations. The masonry partitions are arranged in the same way as masonry walls on a cement-lime or cement-clay solution of the composition 1:1, 3:10.
Pipes. Chimneys are made of burned bricks. The pipes are placed near the walls without crossing or binding them, which ensures independent precipitation.
Wooden parts of the building. All wooden parts of the structure embedded in the ground walls or in contact with them must be treated with a preservative agent (antiseptics) to avoid the occurrence of dry rot in the room.
The simplest composition is a 10 % solution of iron or copper sulfate or zinc chloride (1 kg of one of these chemicals is dissolved in 10 liters of water). You can also use a 3% solution of sodium fluoride. The antiseptic solution should be applied with a brush in two doses with a break of 1-2 hours.
Interior finishing. There are several finishes that give the same effect as traditional plastered walls, but in our time of falling skill levels and skills of craftsmen, along with a huge number of offers of modern materials, you need to think about other finishes. Maybe you should not completely hide the texture of the ground walls, as it can give a special character to the room. For example, wall treatment with linseed oil followed by polishing or light whitewash on the soil blocks.
Many years of experience in adobe construction, when the strength of adobe is less than the strength of the soil blocks, shows that damage to non-plastered adobe walls during the year under adverse conditions goes into the depth of the wall slightly, to a thickness of no more than 4 mm. In this case, non-plastered walls will give only 4 cm of wear during the ten-year period of their existence. It is advisable to plaster only after this period in order to reduce the work on preparing the wall surface for plastering.
In the South of Russia, the soil block walls cannot be plastered, but only rubbed with clay and whitewashed with lime or chalk.
In any case, plastering should be started after the joints and adjacent sections of blocks are completely dried, when the wall draft is finished.
External plaster can be made with lime-sand, cement-lime or organic clay solutions in several ways.
- Plastering is produced in three stages: first, spray with a liquid solution 3-4 mm thick, then a primer 12-15 mm thickness and a cover 2-3 mm. Previously, the wall surfaces are cleaned with wire brushes and sweep. It is not recommended to wet the wall surface made of ordinary unstabilized soil blocks. To improve the adhesion of the plaster to the masonry, it is recommended to seal the seams with flat crushed stone or wooden pegs that protrude 1-1.5 cm from the wall surface.
The plastering is made with a solution on the shingles stuffed directly on the wall or on the slats laid every three rows during laying in the seams of the latter.
The wall is upholstered to a height of 1 m from the base with tar paper, and then plastered according to the second method. The first method is not expensive and is quite durable. Wooden pegs 7-8 cm long are driven in a staggered order into the seams of the masonry, while the solution is not yet strong (at a distance of 10-15 cm from each other). Pegs come out of the wall surface by 1-2 cm, depending on the thickness of the intended plaster.
When the walls settle, a layer of plaster made of clay, sand, lime and some fibrous additive 1:1:0.5:0.1 is applied to the pegs. Mixed solutions 1:0, 5:4 (lime, cement and good coarse sand) are stronger.
Plastering by the latter method is done only on the side of the building from which you can expect the greatest damage to the walls by rain.
The walls made of ground blocks can be faced with ceramic or concrete tiles, but not earlier than a year after construction. In this case, the walls are pre-plastered with cement-lime mortar to meet the requirements listed above. Before the plaster hardens, ceramic tiles are installed with a layer of mortar 10-15 mm thickness laid on them. Before installation, the tiles are soaked in water for 2-3 hours.
Plugs are clogged under the cement plaster in the wall and they are attached with 30-50 cm sew slats, which stretch the metal mesh.
Decorative and protective coatings of external walls made of the soil blocks serve not only to protect the walls, but also to give the walls a more expressive architectural appearance.
The coating is understood as a system of preparatory and cover layers.
Preparatory layers are called primer and putty layers, which provide a strong connection between the surface to be painted and subsequent layers, and align the surface to be prepared for painting.
Covering layers are the main film of paint and varnish material of the required thickness, applied to the preparatory layers, having a strong bond with it and providing protective properties to the entire coating system.
The coatings are classified into groups depending on their resistance to aggressive media.
Paint compositions used to obtain coatings are divided by the type of binding materials into water (lime, cement and others), emulsion (emulsion paints and compositions), anhydrous (enamels, lacquers, oil paints).
For protective and decorative finishing of external walls on the plastered surface, weather-resistant water, water-dispersion (emulsion) or organic and soluble (anhydrous) compositions can be used.
The preparation of external walls for protective and decorative coatings is performed as follows.
Protective and decorative coatings are normally applied on a plastered surface.
The plaster must be firmly connected to the base and must not peel off from it. The plastered surfaces should be flat, smooth, without traces of the grout tool, streaks of solution, spots, efflorescences. Cracks, bumps, quilted, gaps are not permitted.
The basis of water-dispersed protective compositions is formed by -materials based on polymer water-soluble binders-synthetic butadiene-styrene, divinyl nitrile and other latexes, polyvinyl acetate dispersion, acrylic emulsion.
Coatings based on these polymers are characterized by high weather resistance, good adhesion to the base, and durability.
The walls are painted with lime compounds. Glue painting is permitted on an alabaster cover.
In damp rooms, we recommend oil painting on the cover made with cement-lime mortar.
During the operation of buildings, it is necessary to carefully monitor the serviceability of the roof and exterior plaster, quickly eliminate damage, avoiding soaking the walls of soil blocks, as this can lead to uneven precipitation.
In the building, it is not recommended to perform processes that release a large amount of moisture and steam (washing, bathing), which should be done in special rooms (kitchen, bath, etc.) equipped with proper ventilation.