The foundation is made of rubble and clay. Rubble stone foundation: how to lay, advantages and disadvantages, tricks and tips

The construction of any house involves the construction of a foundation. For its construction, in order to save money, you can use natural stone such as rubble. This is one of the cheapest natural materials.

In its structure, rubble stone is quite hard, so a foundation built from it will be reliable and durable for many years.
You can make such a foundation yourself, without the help of specialists, which will significantly save your budget. Building the foundation for a house is quite hard work, but it is possible to carry out this activity with your own hands if you work hard. It should also be noted that when the construction of a foundation made of rubble stone is mentioned, it means the construction strip foundation. It is possible to build a pillar foundation, but the technological process will be quite complicated. Therefore, preference is given to the first option.

List of necessary building materials and tools

Before starting construction, it is necessary to purchase the following materials:

Stone. Its size along the longest diagonal should not exceed 50 cm. When choosing this material, pay attention to the fact that it does not have defects on its surface and is clean. It must also meet standards such as strength, frost resistance and water resistance.

Small crushed stone for backfilling voids.

Sand for forming a base for and for mixing cement mortar.

Cement used to mix mortar. Moreover, the higher its grade, the stronger and more reliable the structure will be.

Ruberoid will serve as a waterproofing layer.

In order to begin building the foundation of the house, prepare the following tools:

Shovels: shovels and bayonets.

Container for mixing the solution.

Trowel.

Water and horizontal levels.

Hammer-pick, sledgehammer, mallet, rammer, chisel.

Roulette and plumb line.

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Preparatory work for the construction of the foundation

So, having prepared all the building materials and tools, let’s begin building the foundation of the house with our own hands. First you need to dig trenches. Their depth should be below the soil freezing level. And its width should be such that the foundation being built is 20-30 cm larger than the walls, but not less than 40 cm. You also need to decide whether formwork is needed or not. Formwork is used in cases where the soil is quite loose and susceptible to crumbling. Upon completion of the work it is removed. If the soil on your site is quite dense, then you can refuse to build it.
Then you need to make a sand cushion at the bottom of the trench. Its thickness can vary from 15 to 30 cm. Sand must be poured in several stages. Each layer of sand must be compacted using a tamper. To make this process easier, water the sandy base.

A waterproofing layer is laid on the sand cushion thus formed. To do this, you need to take sheets of roofing material and place them at the bottom of the trench. Lay them overlapping to avoid gaps between the sheets. This layer of waterproofing will prevent the cement mortar from seeping into the sandy base.

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Technological process of building a stone foundation

Now that everything is prepared, let's start laying rubble stone with our own hands. For the first layer of the foundation, it is necessary to select in advance stones that have flatter horizontal surfaces. If there are not enough such stones, then you will need to arm yourself with a hammer and chisel in order to give this material the necessary shapes.

At the corner points of the future foundation and at the intersections of walls, you need to place stones with your own hands with the most even surface, and they must be strong enough. When laying the first row of stone, place them along the trench. Press the rubble into the sand so that it lies tightly there and does not wobble.

After laying the rubble directly between the stones, the voids are filled with crushed stone. Then they begin to fill the laid and compacted stone with thin cement mortar. This is done so that the liquid solution can penetrate and fill all the voids.

It is quite simple to prepare this mixture with your own hands: to do this, take 1 part cement and 3 parts sand. These components must first be sifted so that the future solution does not contain various pebbles and debris, since the quality of the mixture depends on this. Mix these ingredients thoroughly using a shovel. Then add water little by little and mix everything at the same time. Add liquid until you get the desired result.

It is advisable to prepare this mixture from cement, the grade of which is not less than M-100. Then a layer of rubble stone is covered with the same cement mortar, but already thick. When the stones are tightly adjacent to each other, the thickness of the cement layer should be minimal. Second row building material need to be laid across the trench. That is, the location of the buta in two adjacent rows will be perpendicular. In this way, the rows are ligated.

The construction of buildings of any purpose and complexity is not complete without laying the foundation. Various methods and materials are used for this. Among this list, it is worth highlighting the rubble foundation, which has been popular for a long time.

What it is?

It is the construction of the foundation that is the fundamental stage that precedes all others. construction work during the construction of houses or other structures. Despite the fact that the construction market offers a wide range of different materials, natural raw materials are still in demand. One of the natural construction raw materials used to lay the foundation is rubble stone, which is a high-quality and environmentally friendly rock that has found its application in construction.

Some people mistakenly believe that using stone is impossible when laying a foundation due to its irregular shape, however, even with minimal experience in construction, you can competently arrange the stone foundation of a building even with your own hands.

This is exactly the kind of foundation that most builders preferred to build in the recent past.

Now the rubble concrete foundation for buildings increases their visual appeal, and most importantly, it allows you to carry out construction work at minimal cost, using a fairly simple technology for implementing the construction project.

As practice shows, the service life of a rubble foundation reaches about 150 years; there are even fortresses in the construction of which this natural material was used. Main feature Rubble stone bases are resistant to groundwater, as well as soil freezing.

Experts use several varieties of this raw material in their work:

Industrial stone. Its production is carried out in special complexes in which crushed stone is produced. This type is in demand during work to strengthen railway tracks or hydraulic structures.
Round stone. The process of forming such a breed occurs naturally.
Postleafy. It is characterized by irregular geometry, due to which rubble is in demand for laying the foundation, and also acts as a decorative material used in landscaping work.

There are no strict requirements for the rubble rock used to lay the foundation of the building, the main thing is that the raw material does not crumble.

It is best to use tiled or pastel rock. This material has smooth edges, which makes installation easier, since it will be much easier to place samples of the correct shape as closely as possible to each other.

Analyzing the technology for constructing a foundation from rubble rock, we can say that the principle of its implementation is similar to the work on the construction of brick walls - the components are placed on top of each other during laying, and the connection of all elements occurs using a mortar. The only difference is in the materials and the composition used to provide the bond - for a stone base it is necessary to use a durable concrete mortar.

A standard strip rubble foundation usually has a height of about 1.6 m with the base located on a special bed of sand and drainage.

The foundation is laid above the freezing level of the soil, usually at a distance of about 30 centimeters, then the base of the building and the ground floor are located.

pros

Among the features of the rubble foundation It is worth highlighting its main advantages:

The use of this rock allows the construction of foundations that will differ in height and strength. This is relevant for the construction of private houses with a large area.
The raw materials consist of natural components, therefore they belong to the group of materials that do not pose a danger to human health. In addition, the material does not harm the environment.

Rubble stone foundations are distinguished by their durability and reliability, since the rock has excellent strength indicators.
Such designs are wear-resistant.
The material can be used to build the foundation of any house, with different shapes and areas.
Reinforcement for such foundations is rarely required.
The stone is resistant to moisture, so the base is not destroyed by melted or groundwater.

Cobblestones in cross-section are a very attractive material.
The rock can be combined with other construction materials. In some cases, the part of the base that protrudes to the surface is built from brick, and the remaining part, which is located in the ground, is built using rubble stone. This method, according to expert reviews, makes it possible to save on construction work.
The rock base has high resistance to negative temperatures.
It is noteworthy that the rubble foundation practically does not require any repair work, since defects do not form on it over time.

Minuses

Foundations made from this material also have disadvantages.

These include the following points:

Since stone is a natural raw material, its cost is quite high.
For preparatory work Before building the foundation, it is necessary to calculate the amount of material required, which requires certain qualifications and experience. All technology for arranging the foundation must be carried out in accordance with SNiP; in addition, it is necessary to measure the level of groundwater in the given area.
The entire process of laying stones is done manually.

Irregularly shaped rock is quite difficult to lay out into an even structure.
Erosion of bonds may occur in the rubble stone base - during penetration into cement mortar As water freezes further, the concrete is destroyed, and the wind blows the destroyed grains of sand out of the base, which leads to destruction.
In case of violations in the calculations of the strength of the foundation and the weight of the structure, it may be necessary to strengthen the foundation. It is also necessary in areas where there are signs of soil movement.

Device

Laying work is preceded by preparatory measures for arranging trenches, as well as sorting the rubble - it must be divided based on size. To reduce the time for laying rock, wooden formwork is installed in the trench opposite each other, which can be adjusted in height.

The construction of a stone foundation can be done in two ways:

direct method - which involves pouring concrete into a trench with a layer thickness in which half of the rock will be buried in it;
the opposite option - in this case, the first layer of rubble is filled with cement mortar, which hides it as much as possible, after which subsequent layers of stone are laid.

Before backfilling, most builders advise spreading a layer of polyethylene with high level strength.

It will preserve the properties of the solution without releasing cement laitance. The rock is laid in two parallel lines with a gap for mortar between the elements of about 5 centimeters. The top row should be laid in such a way that the stones overlap the seams of the bottom row.

In order for the solution to be suitable in strength, it is worth using M 500 cement for its preparation. The density of the composition should allow it to freely penetrate into the seams between the rubble cobblestones. It is recommended to moisten the stone a little before laying it to remove dust, which will have a positive effect on the adhesion to the mortar.

How to do it?

When performing work on the construction of a rubble foundation, you should adhere to step by step instructions, and buy everything necessary materials and tools:

sand and crushed stone;
cement;
rock;
solution container;
bayonet shovel, trowel;
building level;
plumb and tamper.

Crushed stone will be used to fill the voids that arise during the laying of stones, sand is needed to prepare the solution, as well as arranging the cushion below, even if shallow foundation. The smaller the bottle, the more it will be needed for the base. In addition, the work will require waterproofing. Roofing felt or any other product can be used as such material.

The technology for laying a rubble foundation includes the following work:

Construction of a trench. It is worth paying attention that its width should be no less than 2.5 meters. This need is due to the large size of the breed. The base tape will be about 0.5-0.6 m.
An indent of about 0.7 m is left on the inside of the tape, and 1.2 m on the outside. This feature will help in moving the formwork. The external gap is filled with sand.
For concreting with laying rock, the formwork must be made in dimensions corresponding to the height of the building’s base.
The inner surface of the boards is covered with a film that will prevent concrete mortar from leaking through the existing gaps between the planks. In addition, it will prevent the wood from absorbing moisture from the composition.

Rubble stone is laid according to the following scheme:

after laying the film on the bottom, the solution is poured;
two rows of stones are laid on it; elements of similar size should be selected;
Next, a layer of mortar is poured in, which needs to be leveled;
ligation of the outer or inner side is performed with a butt row;
after this, the masonry is carried out in longitudinal layers;
the corners of the structure are tied with rock.

During work with the solution, you should monitor the filling of all existing voids.

To ensure that there are no untreated areas left, it is important to prepare a plastic mixture for work.

To increase this indicator, various additives are used, for example, plasticizers for concrete or detergent compositions.

A beautiful and inexpensive rubble foundation has been known to the world since 2000 BC - and some buildings on such a foundation have stood for centuries! That is why they say about him “for centuries.” Its service life actually exceeds 150 years - it’s not without reason that even fortresses were once built from stone. And the rubble foundation of all existing ones is the most resistant to freezing and groundwater. And it is also environmentally friendly. And it’s really possible to build it with your own hands without any additional construction equipment! So, together with the portal site, we figure out where to look for stone and how to build an impressive foundation for a bathhouse from it.

Features of laying a rubble foundation

As a standard, a strip rubble foundation is erected 1.6 meters high with a reinforced belt on top. If you make a good sand cushion with drainage or a more solid reinforced belt, the height can be reduced.

A rubble foundation is usually laid below the freezing depth, with concrete grade of at least 100. It must be at least 30 centimeters above ground level, after which there is a base.

Interestingly, when dismantling buildings of the last century, it turned out that in those days the foundations of rubble stone were laid up to two meters deep, no reinforcement was used, and everything was secured with a simple mortar. Even without waterproofing between the foundation and the wall and any brickwork. And still the buildings stood! We can say that rubble stone in a rubble concrete foundation simply replaces a metal frame.

How to choose a quality stone?

Suitable natural stones for foundation construction are sandstone, cobblestone, tuff, shell rock and limestone. Those of them that have an irregular shape with almost parallel surfaces are rubble.

Traditionally, a rubble foundation is laid out of large stones of similar size and shape. For this purpose, flat-edged stones are chosen, which are tightly stacked on top of each other and held together with cement mortar. How to recognize the quality of rubble stone? If, when split, it does not crush and does not generate dust, it means that good material was found for the construction of the foundation. Second parameter: if you hit the stone hard with a hammer, the sound will be loud and clear. And the stone will not break!

You can even collect rubble stone in the fields. But, if you have the opportunity to order it, it’s better not to waste money. After all, many people don’t even imagine how much of this stone is needed to build the foundation of a small bathhouse - several tons!

But there is another problem with building such a foundation - cleaning them. Washing them is not so easy; it takes time and patience. And if you don’t wash it, there will be no bond with the concrete - needless to say, what will this mean for the foundation?

Plinting: preparing stone for construction

Plinting also helps to make stones smaller - up to 30 kg. And this is how rubble stone is split:

Using a soft pencil and or lines, mark the desired size.
We stretch the cord evenly and press it into a piece of chalk with a notch. Next, we pull the same cord along two points on the stone and release it. When you hit a stone, the chalk will leave the desired mark.
We place a chisel in the marked mark and drive it three or four centimeters into the stone - using a cam hammer. At the same time, we carefully make elbow strikes.
At risk, we split the stone: we place the chisel at an angle and make a strong shoulder blow to it.

It is even easier to split rubble stone along a seam that has formed naturally: to do this, you need to insert a chisel into the seam itself and use a hammer to move it along the crack. How do you know where the crack is? It will have an indentation or darker color at the break.

This is how they achieve two parallel sides-beds of rubble stone, which are needed for laying.

Rubble laying technology: three common options

Here's how to properly build a rubble stone foundation:

Step 1. We dig a trench and install the formwork.
Step 2. We arrange a cushion of 30 cm of clean concrete and reinforcement.
Step 3. On the pillow is the rubble foundation itself.

Before laying, the stones must be wetted so that they better adhere to the concrete and retain their moisture. The rubble stone must be placed correctly - with a gap of 3 to 5 cm, and in no case close to each other.

The long side of such a stone is called a spoon, the short side is called a poke. And in each row of such masonry, a poke should alternate with a spoon - that’s the whole technology.

For laying rubble stone, a sledgehammer, a cam hammer and similar tools are used. The standard thickness of the masonry is 50-70 cm. Clay also does not hurt - it is often added to make the solution more flexible. But just a little!

So, laying rubble stone also has its own special technology. So, you can put it “under the bracket”, “under the shoulder blade” and “under the bay”.

Place it under the shoulder blade like this:

Step 1. We lay the bonded row dry on the base prepared in advance.
Step 2. We compact the stone well and fill the voids with smaller stones. Fill with liquid solution.
Step 3. Now we place the spoon row - with the long side. The thickness of both the first and second rows is up to 30 cm, and when laying stones, you need to select such that the height of the row is almost the same (to check, we install beacons with a cord).

It is extremely important to ensure that the stones do not touch each other anywhere without mortar.

Whether to install formwork for such a foundation or not depends on whether you need perfectly smooth foundation walls for subsequent finishing or not.

But the laying under the bay is always carried out in formwork. The strength of such a foundation is very low - only a light frame bathhouse can be built on it. Therefore, for such masonry, use a vibration compactor: this will increase its strength by up to 40%. The stones for it are also not particularly selected. The order of work is as follows:

Step 1. Prepare the trench and base, which we fill with coarse sand and compact.
Step 2. Lay the bonded row, crush it and fill it with liquid mortar.
Step 3. Place the second row of spoons, crush again, compact and tamp the stone.

Here the work is already being carried out as usual, but after that a plastic solution with a cone slump of up to 6 cm is spread in a layer of 40-60 cm and everything is compacted with a vibrator - until the solution stops penetrating into the masonry row.

But for masonry “under the bracket” the stones are selected to be of the same height - according to a template, and the verticality and horizontality of the surfaces and corners of the masonry itself are constantly checked.

An important point: it is necessary to ensure that the stones do not wobble when laying and that the seams are bandaged. The ideal stone for such a foundation is 20x30 cm. As for its area, it is calculated using the following formula: the width of the rubble stone = 1/3 of the width of the foundation.

Is this type of base suitable for every bath?

Some experts note that the heaviest buildings have long been built on the rubble. After all, rubble tape is much more mobile and less rigid than a regular foundation. Therefore, if it’s good not to “crush” her brick walls and the presence of a second floor, the bathhouse may, unfortunately, not last long. But wooden steam rooms, although they are light, can be safely installed on such a basis: after all, wood, due to its fibrous structure, works well “in tension” and it is not scary for it if the foundation underneath it “moves” slightly, whereas brick and concrete the wall, if it could not sufficiently press down and “pacify” the rubble foundation, will definitely crack. What a paradox!

Rubble concrete foundation: simpler and stronger

The main rule for constructing a rubble concrete foundation is this: it must consist of concrete mortar and rubble stone in a one-to-one ratio. In general, the proportion of stone in relation to the total volume of the foundation can be reduced only to 40%, no less. The solution for such a foundation also includes filler: small rubble stones, gravel, crushed stone, broken and burnt bricks. And the binding component is cement and cement-lime mortar - this depends on how wet the soil is.

The rubble concrete mass must be laid out in wooden formwork, gradually filling the entire volume. But the walls of the trench must be covered in advance with sheets of roofing felt or roofing felt. The filler is placed first in the prepared trench - in a layer of up to 15 cm. It is carefully compacted with a heavy tamper and filled with solution. Then sand again and mortar again. And the concrete solution for such a foundation is prepared from heavy cement grade M-400 or M-500. Crushed stone - up to 30 mm, sand - coarse or medium. They need to be mixed in a ratio of one to three. The mixture should eventually be dense and liquid enough so that all the voids in the masonry are filled.

The foundation turns out to be very strong, although not as beautiful as a rubble one. Still, the most important thing is that even a novice amateur can build a rubble and rubble concrete foundation - the technology here is much simpler than the construction of complex reinforced strips.

If there is cheap “bedded” natural stone in the region, a do-it-yourself rubble foundation will cost much less than a monolithic or prefabricated structure made from FBS blocks. Rubble is not sorted into fractions and does not have smooth edges, so instead of cords for masonry or pouring, formwork is often used.

Rubble stone ensures a reduction in the foundation construction budget by at least one and a half times. The strength of the structure is comparable to a monolith, the main filler of which is the same material, only of smaller fractions. The basement part of the house does not have to be decorated; the underground part is waterproofed by treating the seams with special compounds.

The construction of a rubble foundation is similar to masonry or concreting. In the first case, a cement-sand mortar is used with the addition of penetrating mixtures or liquid glass, which impart water-repellent properties.

There are two options for constructing a rubble foundation:

concreting with laying of rubble stone;
rubble masonry.

The foundation is made using rubble masonry.

Attention! If the rubble concrete foundation is not planned to be lined in the basement, this massive structure will become a cold bridge. Heat loss through floors and ceilings will increase, since at subzero temperatures the material will freeze through.

Earthworks and foundation

At the stage of moving the full-scale axes of the house into the building area, it is necessary to take into account several factors that significantly affect the productivity and quality of work:

the size of the stone is much larger than the brick, the tape is 45 - 60 cm minimum;
It is very difficult to reinforce masonry, so sometimes plaster mesh or fine mesh Chain-link mesh are used;
even for masonry, it is better to make formwork that can be moved in height, which will sharply increase the pace of work;
The rubble material should be sorted into small and large stones before starting work.

The construction of trenches is standard, 0.5 - 0.7 m is added to the width of the tape from the inside (comfortable for rearranging the formwork, opening joints), 1.2 m from the outside (necessary for insulating the blind area, laying drains). The trench is dug to the design depth, since below the freezing mark there are guaranteed to be no heaving forces, and there is no need for an underlying layer of non-metallic material.

Attention! If you plan to pour a rubble concrete foundation, in order to avoid leakage of cement laitance into the lower drainage layer, it is necessary to make a footing 5–10 cm thick, twice the width of the tape, and fuse 2 layers of rolled waterproofing onto it.

Features of formwork design for different technologies

The technologies for rubble masonry and concreting a foundation strip using rubble stone are very similar. The differences are:

when laying, stones are laid on mortar;
When concreting, the formwork is filled to 30 cm with concrete, into which large stones are embedded.

Unlike brick, rubble has an uneven shape and it is very difficult to lay it along a thin cord. Therefore, it is easier to fix two shields along the outer and inner edges of the tape in order to lay the stones close to them.

Therefore, the formwork design for these two technologies for building a house foundation will be different:

for concreting, standard shields will be required for the entire height of the tape with a polyethylene film stretched along the inner surface so that the mixture does not flow out through the cracks and the concrete does not dehydrate upon contact with wood;
for masonry, a shield 30–50 cm high is sufficient, so that it can be conveniently moved in height as the foundation walls are built up.

Attention! It is not recommended to use slot foundation technology when the formwork is trench walls. If the soil does not crumble from its surfaces, this indicates a large percentage clay, which is guaranteed to swell in winter and destroy the masonry. It is necessary to widen the trench, lay drains, backfill with sand, and ASG.

For secure support wall material At home, on the upper edge of the rubble foundation, it is necessary to select stones with a flat surface for the last row. Unlike classical masonry, the construction of a rubble structure is more reminiscent of concreting:

a film is laid on the underlying layer;
a bed of mortar 3–5 cm thick is applied to it;
two longitudinal rows of stones of approximately the same size are installed;
then the mortar is laid again, the bed is leveled;
ligation is performed with a butt row on the outer or inner side;
in the third row the poke is placed on the other side;
then several rows of spoons are installed (long side along the wall);
At the corners it is necessary to bandage with whole, ¾ stones.

Some experts wet the stone with water (dipping before installation without soaking). However, this material is not fired in ovens and usually has natural moisture, so the procedure is not necessary.

Attention! The consistency of the solution should ensure that the joints in the previous row are completely filled. To increase plasticity, add a Superplasticizer or a few drops (5 - 7 per concrete mixer) of Fairy type detergent.

Concreting using rubble stone

Laying the rubble concrete mortar into the formwork is a little more difficult; you will need a reinforcing bar or an internal vibrator. The crushed stone fraction in the mixture should be small (5/10 mm) for better filling. The technology looks like:

laying concrete - a 30 cm layer is poured inside the formwork without compaction;
stone distribution - the rubble is not covered, but laid out in a 20 cm layer so that the outer edges come into contact with the formwork panels;
recessing the rubble - with fittings or the tip of a deep vibrator, on which a special visor is put on.

After immersion, the stones should not stick out from the concrete. The break between laying the mixture and stones should not exceed a quarter of an hour. If it is planned to stop work, concrete or rubble runs out, the laid stone must be covered with a mixture compacted with a vibrator attachment.

Attention! The upper 30–50 cm are concreted without stone; before laying the mixture, a reinforcement cage is installed on the last row of rubble so that the upper belt of the longitudinal rods is recessed into the concrete by 2–5 cm (standard protective layer).

Waterproofing

Depending on the technology used for making the foundation of a house using rubble stone, the surface of the tape does not have the same roughness. Therefore they apply different ways waterproofing of the underground part:

rubble concrete foundation - the surface is more even, possible over a primer;
rubble masonry - the surface is uneven, plastering with moisture-resistant mixtures, coating with bitumen, polymer or epoxy mastics is used.

Attention! If penetrating compounds are introduced into the solution or concrete, waterproofing of the structure is not required.

Advantages and disadvantages

The main advantages of a rubble strip foundation for a house are traditionally:

reduction of the construction budget;
reducing work time through the use of large-format material;
high performance characteristics (weather resistance, strength).

The disadvantage of rubble masonry is the lack of reinforcement and excessive mobility of elements inside the structure. When concreting into formwork using rubble stone, there are no disadvantages at all. The tape can be qualitatively waterproofed and covered with thermal insulation. It is a monolithic structure with an upper reinforced belt, which compensates for tensile loads from possible swelling of soils.

Thus, the construction estimate country house it is quite possible to reduce it through the use of budget building materials. It is more difficult to work with rubble stone than with brick, but the large format allows you to reduce construction time.

Rubble foundation is a budget and aesthetic solution for residential or country house, garage and bathhouse. It is strong, durable and environmentally friendly, because the structure is assembled from natural stones. Rubble foundations are not as common as reinforced concrete ones for various reasons, one of which is the lack of awareness among developers. Let's compensate for the lack of information and consider this type of construction from all sides.

general description

The rubble foundation is predominantly a strip structure, sometimes a columnar system. The main volume is made up of rubble stones - up to 90%, the rest is cement mortar of a grade not lower than M100, optimally M200-M300, depending on the mass of the future structure.

Large and durable stones are used for masonry. Preference is given to cobblestones of relatively regular shape with parallel edges weighing up to 50 kg. Actually, the larger and stronger the fragments, the faster the installation is carried out and the stronger the foundation.

Unlike other types of structures, rubble foundations are not reinforced for several reasons:

Bandaging the stones during laying creates sufficient strength for the tape/pillars, similar to a brick wall;
Laying straight reinforcement in stones with non-ideal shapes is not an easy task.

However, reinforcement at the plinth level will help avoid the formation of cracks during wall shrinkage and compensate for the unevenness of incoming loads, because the foundation itself does not have elasticity and impeccable rigidity (not to be confused with strength).

Most historical buildings of European architecture stand on rubble foundations, and, it should be noted, they have been preserved almost in their original form for more than 200 years. A striking example is historical St. Petersburg, where the bulk of the foundations are piled wooden foundations, the rest are rubble.

Advantages of a rubble foundation

A foundation made of rubble, in comparison with structures made of other materials, has a number of advantages:

Cheapness– the first and most powerful argument in favor of buta. Any stones suitable for strength and size are suitable for it. You can extract them yourself from a block or purchase ready-made ones, but even in this case, rubble will cost less than reinforced concrete (about 600-900 rubles per ton versus 2000-2500 rubles).
Strength The compression ratio is higher, the larger the stones used. As already mentioned, the design does not include reinforcement, because natural rocks cope with the function of distributing the load.
Durability demonstrated by ancient buildings of St. Petersburg and Paris (a striking and famous example is Notre Dame Cathedral).
Aesthetics – the base, made of rubble, does not require finishing and looks natural and complete.
Relatively easy installation: you can handle the design yourself; there is no need to knit complex frames. But by simplicity we mean installation, not speed.

Flaws

What you need to keep in mind when choosing a rubble foundation:

Setting up the tape is labor-intensive: the structure is laid below the freezing level of the soil in a compacted base, the height of the wall is considerable.
Long construction times for self-installation. In addition, some knowledge of stone placement will be required to ensure a good dressing. It will take more time to make stones if you decide to bomb the block yourself.

Preparation of material

The durability of the building and its safety depend on the correct choice of stones.

Rubble is fragments of rocks of different origins: limestone (shell rock), dolomite, granite, marble, etc. Rubble stones are obtained by explosion in quarries for mining or through the natural destruction of rocky blocks.

How to choose a high-quality rubble that can provide strength for the foundation? To do this, you don’t need to push a mountain into the laboratory; use a few life hacks:

Inspection is the first step. The rock should not crumble; the bulk of the batch should contain only large stones of uniform color without obvious signs of destruction and colonization of microflora.
Hit the stone with a hammer as hard as you can. A “good” copy will not crumble or crack, and will make an audible ringing sound. It is especially important to check limestone and shell rock in this way, which are not always distinguished by excellent strength.
Determine the number of voids and total porosity visually - rock that absorbs water is not suitable for construction.

The shape is also important when choosing. For laying, the most convenient stones are flat ones with relatively parallel spoons and pokes. Their installation requires less labor, including adjustment. It is also possible to work with free-form stones, but it is more difficult to arrange and create a dressing with them.

Important! Before work, the stones are thoroughly cleaned of dust to increase adhesion to the cement solution, and also thoroughly moistened.

Masonry mortar

The minimum grade of mortar for masonry is M100, this can be used when constructing a light structure, for example, a garage or utility shed. For a house, of course, you need stronger material - M250-M300 and higher, in proportion to the massiveness of the house.

Standard proportions for preparing masonry mortar when constructing a wooden or concrete block cellular structure two-story house 1:3 (cement M400 and medium river sand). The consistency of the mass should be standing - a lump of mortar should stand on the trowel and not spread. Together with mixing water, it is recommended to use plasticizers that increase plasticity without loss of cement strength. If the sand contains clay admixtures (about 15-20%), this will also help make the solution more plastic.

Important Rules

The stones in the masonry must be laid in such a way that the vertical seams of each subsequent row overlap;
The distance between the stones should be minimal, and voids should be excluded;
Large stones at the bottom, small ones at the top;
The stones must be laid taking into account the rigidity of the overall structure, so that individual elements do not tend to fall out of the system when exposed to load.

Basic calculation

Due to the lack of reinforcement in the rubble foundation, to ensure the rigidity of the structure, it must be laid below the level of soil freezing in the region, 20-30 cm lower. The masonry is carried out on a compensation cushion of sand and crushed stone with a total thickness of about 20 cm, carefully compacted. The height of the embankment can be taken into account towards the total height of the foundation. The presence of groundwater is also taken into account; if it is abundant, drainage arrangements are required, but it is prohibited to reduce the height of the foundation above the freezing level.

The width of the wall is determined as usual - wider than the house walls by 10 centimeters or more or according to more accurate calculations.

Basics of laying a rubble stone foundation

The structure is laid using fresh mortar and general principles masonry

When the pit is ready, the soil must be thoroughly compacted with vibrating plates. This is necessary to create the most stable and rigid foundation. The bulk sand and gravel cushion is also compacted by vibrocompression. It is recommended to fill it with a layer of concrete preparation 5-10 cm thick with M100 solution.

The first row is laid out from the largest stones. They are placed as close to each other as possible. It is necessary to achieve “solidity” of the stone structure - masonry mortar is needed only to connect the fragments together.

The next row is laid in such a way that the vertical seams overlap with stone. In installation, such a quality as intuition is very important - it is difficult to make ideal masonry from irregularly shaped stones, so selection is carried out by eye, taking into account the size of the seams, cobblestones and their shape. “Bricks” of irregular shape must be laid taking into account their rigidity so that they do not tend to fall out of the structure. The result should be a system that supports itself.

Before laying each subsequent row, first of all, stones of an optimal height of up to 30 cm are selected, which will be oriented towards during the entire process and laid out in the corners. These are "beacons".

Throughout the entire process, the verticality and horizon of the structure are monitored.

The voids of the laid row are filled with mortar, the stones are first adjusted to dry, then driven into the structure with a hammer, this is especially important when working with irregularly shaped cobblestones. But caution is important in everything.

The top row must be made as even as possible with careful selection of stones. When the process is completed, a reinforcing belt is made - approximately 5 cm thick, into which steel reinforcement with a diameter of 10-12 mm is laid in increments of 15-20 cm. That is, for a wall 30 cm wide, it is optimal to lay 2 rods at a distance of 20 cm from each other. To ensure reliability, they are tied with transverse reinforcement with a diameter of 6 mm (knitting wire). You can make the frame yourself or order a ready-made welded or knitted one.

When working with columnar foundation the masonry is carried out in a similar way, the reinforcement occurs along the floor beams.

Waterproofing is laid over the reinforcing belt and subsequent construction occurs.