Unlike manufacturers of modern finishing mixtures clay plaster truly is an environmentally friendly building material. She has undeniable advantages, and its technical and performance characteristics are quite sufficient to solve most problems in construction.
About this, and about the types of compositions, and the right technology DIY application will be discussed in this article.
Most often, this plaster is used for finishing adobe (clay) and wooden walls. There are certain advantages and disadvantages of clay plaster timber house, log house or structure made of rounded logs.
Plastering wooden walls inside a house with clay, photo of a living room with a fireplace
Advantages:
Flaws:
One of the oldest recipes for preparing clay mortar for plastering walls has the following proportions:
Such a large scatter of sand occurs because the clay in different regions has different fat content. The fatter the clay, the better its plasticity and higher adhesive abilities. The fat content of clay for plastering walls is determined simply. A small lump is soaked in water and a ball with a diameter of 50 cm is molded from it. The material should knead well, but not stick to your hands. Then the ball is squeezed in the middle, if it has turned into a neat pancake, then such a material is greasy and suitable for plastering with clay, and if it cracks at the edges, then such a material is skinny and unsuitable for wall decoration.
There are numerous ready-made refractory compositions on sale with the addition of lime, gypsum or cement binders. However, for plastering stoves it is enough to use fireclay clay, and fiberglass as reinforcement. Previously, asbestos fiber was used, but it is too harmful for humans.
Furnace finishing with clay plaster, composition with fireclay clay
Clay plaster with the addition of a small amount of cement, in the proportion of 1 part cement to 7 parts clay-sand mixture, obtains a fairly high resistance to moisture. at the same time, it can absorb up to 60% of moisture from the atmosphere, which has a positive effect on the microclimate of the bathroom.
Bathroom finishing
The traditional material for insulating plaster, horse dung, is now quite scarce, so plaster wooden house Inside, clay for insulation is made using a composition with sawdust, which is mixed into a standard mixture, but without adding straw. Plastering a wooden house with clay and sawdust is done exclusively indoors.
The main way to avoid cracks when plastering with clay mortar is to use reinforcement with metal wire or shingle the walls. In addition, the ratio of ingredients is slightly changed towards reinforcing substances of natural or artificial origin. Add more straw and less sand. This ball of plaster is intermediate, as it does not have a very neat appearance.
Solution with big amount straw avoids cracks
Video of the plastering process clay walls houses made of adobe (adobe):
Clay plaster, the composition of which is simple and literally lies under our feet, is increasingly found on construction sites as facing material for interior and exterior decoration. It is known that it was the main material for masters many centuries ago, why are we returning to this experience again today?
The return to ancient construction traditions is not accidental. Modern mixtures for finishing houses practically do not exist without chemicals, which over time harm the body. The cheaper the composition, the more harmful it is. Expensive plasters are not affordable for everyone, and they do not become less chemical. Clay interested consumers primarily because of its environmental friendliness, because the ancient masters did not have a chemical industry.
And even not so old village buildings where this material was used are still functioning properly, which means that the clay does not crumble after a couple of years, but behaves like a full-fledged durable one. natural finish, not only not harmful, but even beneficial for humans. Plastering walls with clay is cheap, and for those who are especially thrifty, there is an opportunity not to spend a penny on the components, but to dig them themselves from the nearest quarry, river, or even on their own site. After all the mixture requires only clay and fine sand. But this is an activity for extreme sports enthusiasts, because the depth of good clay is about 1.5 m, and not so little is required.
Even if you buy ready-made mixtures, they are quite cheap. When choosing, you just need to pay attention to the place of extraction, because clay is a good adsorbent of harmful and sometimes radioactive contaminants. There are no problems with the color of the plaster, because natural clay can be of several shades, roughly representing the entire palette from red-red to blue, and this depends on the location and depth of extraction. Dyes, although natural, are rarely added, and natural fillers, such as straw, can be used for a textural effect.
In addition to being cheap and environmentally friendly, this has a number of advantages. Therefore, before instructing how to plaster with clay, let’s consider what we win and what we lose. The layer that you get on your walls will not soon deteriorate, which will be indicated by numerous cracks, because the clay is very elastic, and gives this quality to plaster mixture. Its appearance will always be presentable and original; like a natural material, it is not afraid of humidity, temperature changes, wind and even moderate earthquakes. Its density creates the effect of preserving the room without letting harmful substances, for example, exhaust from the street, it is believed that even electromagnetic radiation to some extent delayed by such walls.
After ten years, the first crack may appear, but restoration is done almost instantly, and it is unlikely that it will be necessary to cover the entire wall; it is enough to fake the problem area. The layer of clay plaster breathes well, allows moisture and steam to pass through, the microclimate in the room will be almost ideal of all possible options. And you don’t have to wait for unwanted guests in the house; various kinds of insects simply won’t be able to gnaw through the strong bonds of natural clay. The advantages include the hypoallergenic nature of this material, as well as the cleanliness of not only the layer on the walls, but also the construction process. No harmful waste is generated, because everything is taken from nature, and there is no shame in returning the excess to it.
It would be unfair not to mention some of the difficulties that will have to be faced. If you are doing it for the first time, then you will experience all the capriciousness of clay plaster, because preparing it is not so easy, because there is no recipe; readiness is assessed by a practical method. We will try to help you master it, but if available experienced craftsman It's better to take him to help. By the way, finding such a person is also not easy, because clay is not yet so popular, and previously it was not taken into account at all; few people really know how to work with it competently. The plastering process itself is quite lengthy; you will have to wait a long time for each layer to dry, and if you do external finishing with this material, restoration will be required almost every year. Although the plaster will not crumble, it will crack frequently.
Let's start describing the work itself, because there are many nuances here, so we won't be distracted by theory anymore.
Clay plaster is heavy, so adhesion must be very high. To do this, it is advisable to have noticeable roughness on the wall, but it is better to build shingles ( wooden grate). If the walls are brick, clean the surface of any remnants of the previous finish and open the seams. Then the clay will lie confidently and for a long time. Wooden house It definitely has to be with shingles; making notches on logs is a thankless task. You should not use metal, since clay is unlikely to be able to press into it well, it is too dense.
A pure mixture of clay and sand is used for finishing plaster, because she is very “cold”. The clay should first be soaked in water for 2-3 hours, then a little more water is added and mixed thoroughly to obtain a homogeneous mass. Then sand is poured into the container and the composition is mixed again. But the proportions need to be selected experimentally; they will depend on the initial fat content of the clay. This can be checked in several ways, but the fastest and does not require a perfect eye is the ball method.
To begin with, achieve such a state that the mixture does not stick to your hands; this is done by gradually adding water. Then take a little mixture and make a ball 2 cm in size. Place it on hard surface and flatten it, not to a thin pancake, but to an impressively plump one. Now pay attention to the edges, if cracks have formed on them, then the solution is not plastic, more clay is required, if there are no cracks, then you have guessed the proportions and you can start working. On average, 50-80% sand is required for the solution.
The basic plaster solution is prepared with additives, these can be sawdust, straw, pine needles. This solution holds more tightly, i.e. fillers give a reinforcing effect and retain heat better. The “warmest” is a pure clay solution with the same additives, but it is not plastic and will definitely require finishing, since cracks will not take long to appear.
The first layer is thrown on in sloppy lumps, and in order to better stick them to the surface, you need to make some effort, i.e. press the lumps, and not spank them with a spatula, as is done with other plasters. If this layer is the only one, then it needs to be perfectly leveled with a grater; if not, then it is enough to simply roughly bring the surface to the same level. You need to let the layer dry, this will take a little more than a month in the summer, and all three in the winter.
Then the next layer is applied, usually “cold”, see its description above. Its thickness is small. You can also use a grouting solution, where cement is also added to the clay and sand. In this case, the clay-cement-sand ratio is 1:1:3. The surface should now be smooth. And this layer should dry, give it a few weeks. Do not try to speed up the process; forced drying will immediately damage the coating. Then the wall can be decorated, painted or left in a natural color. If some finishing is still planned, then a number of additional preparatory work, for example, a primer.
Just recently I came across interesting video material. While watching a video about how to build a house from timber, I noticed another story - about how to build a house from straw with your own hands. And after looking, I decided to write about it.
The video was filmed by the settlers of the Ark.
It turns out that the cost of building such frame house made of clay and straw, it is not very large. The technology is also not very complicated. The house turns out warm. The plot itself just shows how to build frame house made of clay and straw, the terms of work, the price of construction, the technology of pressing clay with straw are described. The video is definitely worth watching, even just for your own development. And suddenly, it will come in handy in life!
a return to partially forgotten construction technologies is associated with the trend of using natural materials. They give homes a natural coziness and have good environmental qualities. A classic example of such buildings are adobe houses, the main material of which is a mixture of clay and straw. The buildings gained popularity for their environmental friendliness, natural regulation of the indoor microclimate and relative simplicity.
Adobe house. What it is?
Analogues modern houses made of straw and clay existed in ancient times. Some of them have survived to this day - in the arid regions of Asia and Africa you can find entire adobe cities. Improvement construction technologies led to the widespread spread of clay buildings in the territory central Europe And modern Russia. Properly built clay houses have a service life of more than a century and are safe for residents.
Visually, adobe buildings do not always differ from ordinary ones, although their main “charm” lies in the ability to give the walls any shape and adapt them to objects home interior. Numerous recesses, bathtubs and smooth transitions strikingly distinguish clay buildings from brick and other block-cement structures.
Old technologies are rarely used in their original form, since the performance parameters of modern houses are improved through the use of modern additives. The natural fire-fighting properties of clay, which is prone to baking at elevated temperatures, are improved with the introduction of components that increase strength characteristics.
Clay technology construction
1. Materials that you should stock up on in advance:
wooden boards and beams for building the frame of walls and roofs;
clay;
sand;
straw;
water (well or centralized water supply).
TO additional materials that will be useful during the preparation and finishing stages include:
gravel - for preparing backfill for the foundation;
material for the manufacture of solid or brick foundation;
flat wooden planks for upholstery of house walls;
wooden (metal) formwork or mold for making blocks.
Although the house will be made of clay, it is better to make its foundation classic - strip. A solid and elevated foundation will increase the lifespan of the house and reduce the impact of melt water on the lower part of the walls.
The site for construction should be chosen away from lowlands and access to the surface groundwater. Optimal location clay house - on a hill.
To get the most durable building suitable for our latitudes, it is better to make walls by pouring mortar into the formwork. You can also use clay blocks, which are laid similarly to classic block structures.
A significant reduction in construction costs is achieved by independently extracting clay on your own site. Straw in small quantities It is cheap, and the greatest costs will be associated with the purchase of sand and lumber.
The straw should be dry and free of rot. It is best to buy it immediately after the harvest season, and then leave it for the winter in a dry and ventilated area.
2. Preparation of the solution
Many authors advise using not pure clay, but a mixture of it with sand. Since clay and sand differ in composition for different regions, you can test their different proportions (2:1, 1:1, 1:2, etc.). The clay-sand mixture, to which water has been added until a dough-like consistency is obtained, should be clenched in a fist and dropped onto a solid base from a height of 1.5-2 m. The lump suitable composition It should not crack or become too flat when dropped.
To prepare the solution, you can use a concrete mixer or flat base with edges curved upward (mix the solution with your feet). The clay is crushed to a fine powder, after which sand and water are added to it. There should not be a lot of the latter so that the mixture maintains a highly viscous consistency and does not flow out of the formwork.
Straw is added to the resulting clay-sand solution in an amount of 30 to 60%. The more straw, the lower the thermal conductivity of the walls and their strength (you will have to limit yourself to one floor). The resulting solution is poured into formwork forms placed along the edges wooden frame Houses.
The frame is assembled from beams and consists of vertical and horizontal guides. There should be a blank for the roof on top, since after pouring the walls you need to immediately start covering it. The solution is poured in stages (up to 30 cm per day), after which the wall should be given time to dry. At self-construction the wall usually “grows” by 10-15 cm in one daily cycle.
The outside walls are covered with sheathing made of straw or reed - they create an additional heat-insulating layer. The sheathing is fastened with a thin layer, which is pressed against the wall with wooden flat strips (nailed to wooden supports). The outside of the sheathing is covered with clay or lime plaster.
3. Roof made of straw and clay
Tied sheaves of straw are laid on top of the boarded roof frame, which are then leveled (the rope holding them together is cut). Fix the straw in the same way as the sheathing on the wall - wooden slats. After covering the roof, you can begin to coat it with clay-sand mortar.
The process is carried out from the lower edges of the roof to the ridge. After hardening, the coating will not allow moisture to pass through, but will allow the room to “breathe” and maintain humidity at an optimal level of 50-55%.
Feature: the roof should be filled alternately and evenly on both slopes to avoid skewing.
4. Decorating the walls of the room
What is the difference modern houses from old buildings?
To give additional tensile strength to the clay solution (straw partially copes with this), cattle manure was previously widely used. The same solution was used to plaster the walls of the room, which was called the “muzanka”. The main disadvantage of such houses is the abundance of insects in the walls.
Nowadays natural chaff and firewood are used to increase strength. A couple of centuries ago they were difficult to get, but now they are waste from plant processing.
view of adobe house
The addition of crushed stone or expanded clay increases strength and reduces shrinkage during drying. The auxiliary element is sand. To increase the rate of hardening, cement or lime can be added to the clay-sand mortar. Their additives are used during construction in humid weather, with the goal of reducing the risk of wet wall material becoming wet.
Casein, starch and liquid glass. The latter is an antiseptic, therefore it additionally prevents the appearance of mold and insects.
Application modern technologies construction, including sublimation of a strong foundation, increases the strength and stability of the building. Instead of a clay roof, you can lay out a regular roofing felt covering, which is covered with slate or tiles on top. It won't make it worse environmental properties at home, but will improve performance.
To protect your home from rodents, you need to provide a thin metal mesh under the sheathing.
Features of caring for thatched houses
Fire safety is a separate issue in the operation of buildings. Clay houses with exterior and internal surfaces clay or lime mortar, are less prone to destruction in a fire than ordinary ones. When a fire occurs, the straw in the walls does not ignite, since air access to it is blocked by a layer of clay.
house wall made of clay and straw
Despite the high fire resistance of the walls adobe houses, the wooden parts of the roof do not have it. To reduce the likelihood of fire, wood should be treated with fire retardants. They do not provide absolute protection against fire, but are very effective if the application technology is followed.
Construction companies involved in the construction of houses made of clay and straw claim that it is practically impossible for insects to appear in the walls. This is true only when maintaining low humidity, which is not always possible. Do not neglect the advice to use lime plaster, which will clog the walls for moisture access and will suppress the development of insects.
Before building a house, consider the location of the stove and bathroom. Reflective screens should be placed in places of contact with heated surfaces, and waterproofing should be done in wet areas.
Adobe house: pros and cons of the structure
Advantages of adobe buildings:
clean and healthy "atmosphere";
indoors is cool in summer and warm in winter;
low cost of building materials;
relative ease of construction.
About the features of houses made of clay and straw, as well as personal experience construction of the author, look at the video:
based on Internet materials
In fact, straw has excellent adhesion, and therefore you can plaster it with anything - everything will be equally well applied and adhered to.
However, today we will look at two main types of plasters: cement and clay.
Some people mistakenly believe that clay is not strong enough for a thatched house and, in order to strengthen its strength, decide to plaster the house with cement plaster.
And everything seems to be fine, the house is perfectly protected from external influence, but what is the danger?
The bottom line is that clay plaster reliably protects thatched walls and does not allow moisture to pass through.
Cement plaster easily allows moisture to pass into the thatched walls and back, forming condensation.
To give a more detailed answer to this question, let us turn to chemical properties these plasters. There is such a thing as hydrophilicity. In general, it shows how much the material loves and attracts water.
So, clay is more hydrophilic than straw, and therefore, all the water that is in the straw is drawn into itself by the clay, and then it evaporates.
At the same time, cement is less hydrophilic than straw and therefore, straw begins to absorb all the moisture that is in the walls. What does this mean? After the straw absorbs all the moisture, it will begin to become covered with mold, mildew, and eventually, it may simply begin to rot.
Now the second question: where can moisture come from in the walls if the wall is reliably plastered?
Moisture tends to move from hot air to cold air. Moreover, she moves from high pressure to a lower one. As a rule, the pressure in the house is always much higher than outside, so all the moisture that is in the house (from the shower, kitchen, plants, sweat, etc.) gets inside the walls.
Further, if the wall is plastered with clay, then it retards the movement of water in the wall and at each stage less and less moisture reaches the straw. But even the moisture that gets there is pulled back into the wall by the clay, due to its hydrophilicity.
If the wall is plastered with cement, it does not have such waterproof properties and allows much more moisture to pass to the thatched walls themselves, which is successfully absorbed by the straw in the future.
Therefore, one conclusion can be drawn: based on the chemical characteristics of these materials, it is not advisable to plaster straw with cement, because in the future this can lead to its rotting.
At the same time, clay plaster is much healthier, cheaper and easier to work with and, in addition, will reliably protect your thatched walls from destructive moisture.
Some builders plastering straw walls without a reinforcing base. This is possible where “sticky” plaster with the addition of clay acts as a fastening solution. With less sticky plaster (cement-based), a metal mesh is usually used, especially in areas prone to damage such as corners and around windows. (Fig. 1 ).
As an ecological reinforcement for plaster, you can use reed mesh or thin wooden strips (approximately 1x3cmx2m), nailed vertically or in a cross diagonally every 3-4 cm to vertical (5x5 cm), evenly distributed wooden strips (“shingles”). vertical stripes cut into the surface of the blocks (such grooves can be made with the sharp end of a hammer) and firmly attached to the internal posts or the tops of each subsequent row of blocks are fastened (Fig. 2) using a “straw needle”. Vertical corner guides are made in a similar way.
Separation of walls and ceilings.
When filling the joints of walls and ceilings use wooden system gratings described above or a metal mesh attached on both sides to the frame (Fig. 4). "loose straw" is softly stuffed into the spaces between the slats and then plastered over.
Plastered ceilings have good fire resistance to attics insulated with straw blocks. It is best to use metal mesh in this situation, although you can do without it.
Plastering.
Plastering can be done manually or using a plastering station. Straw walls allow most plastering techniques to be applied. Plaster mortar can be applied different ways- to spread or scatter various instruments. Spreading is easy, but only applicable when using thick solutions. Throwing is much more difficult.
Plastering cement-based is the most well-known, but not as easy to use as lime-, gypsum- and other clay-containing “mud” techniques.
The following components are usually used to make cement-based plaster:
One part Portland cement;
One part slaked lime;
Eight parts of clean, sifted sand.
80% of pure water from the total volume of all components is added to the container. Then sand and lime are poured in. Everything is mixed for one minute. Cement and water are then added as necessary. Mixed again for 10 minutes to create a good, sticky mass.
Plaster is applied in 2-3 layers (in the final layer the amount of sand is reduced to 6 parts). After completion of work, humidity should be maintained cement plaster for several days. This will increase its strength.
Clay-containing “mud” plaster is made from tested clay with a sufficient amount of sifted sand. To prevent cracking, this mixture is mixed with straw in a ratio of 3-5 parts sand to one part clay.
