Our material, equipped with photos and videos, tells in detail about the intricacies of constructing a columnar foundation for a bathhouse in various options.
A separate well-equipped modern bathhouse is the dream of all summer residents and owners of country houses or cottages. To build such a bathhouse, it would be useful to use the services of professional, experienced builders. However, if you want to try your hand and save a little, you can start building a bathhouse yourself.
As with any building, the strength and solidity of a structure depends on its foundation. Since the construction of baths from logs or beams is quite common, the construction does not require a very solid complex foundation. In this case, a columnar foundation for a bathhouse is optimal. It consists of support columns sunk into the ground made of wood, concrete, pipes, stone, brick or cinder blocks.
Preparatory stage
At the preparatory stage, the area is cleared of debris, after which the area for the future bathhouse is marked. The top layer of soil along with grass, about 30 cm, is removed.
Ground work
Whatever material you choose for the support pillars, the method of installing them will be similar, with the exception of the foundation with a grillage.
The installation depth of the support pillars depends on:
- soil type;
- soil freezing depth;
- depth of location groundwater.
You can determine the groundwater level, as well as the type of soil, by digging a hole 1-1.2 m deep. If the soil is not heaving, that is, it does not freeze deeply, and also if groundwater is not found, then this foundation depth is considered optimal.
But if the soil contains clay (heaving soil), then you should measure the freezing depth and dig a hole under the foundation 40 cm deeper than this level. Note that the more clay, the deeper the ground freezes.
If these conditions are neglected, the columnar foundation for the bathhouse poured with your own hands will collapse very quickly.
Support pillars should be located at the corners of the building, along the entire perimeter, at the intersections of walls, under partitions, at a distance of 1.5-2 m, depending on the weight of the structure.
Recesses for posts can be made either with a shovel or with a special drill, which makes holes with perfectly smooth walls.
Depending on the material, the thickness of the recesses for the support pillars may vary, but in any case it should be 7-10 cm wider.
The optimal thickness of the columns made from various materials is as follows:
- 50×50 – for brick and stone columns;
- 60×60 – columns made of rubble stone;
- Ø200 mm – asbestos cement pipes;
- 30-35 cm 2 – reinforced concrete supports;
- 25-30 cm 2 – for intermediate posts.
Under each post, at the bottom of the hole, you need to lay a sand cushion, that is, a covered layer of sand, filled with water and carefully compacted. Next, we’ll tell you how to make a columnar foundation for a bathhouse.
Columnar foundation made of pipes
Pipes made of metal or asbestos cement with a diameter of 20 cm are considered the best option for constructing a columnar foundation. They are easy to cut into pieces of the required length. Such a column should protrude 40 cm above the surface.
To protect pipes from destruction due to moisture, they should be treated with special waterproofing mastics or wrapped with rolled materials, for example, roofing felt with bitumen.
The finished supports are lowered into the recesses as evenly as possible.
In the spaces between the posts and the edges of the hole, fill in the soil that was previously removed from the hole, or sand and gravel that needs to be compacted. The thickness of this layer is 40-50 cm. Next, several reinforcement rods with a cross-section of 12-14 mm are inserted inside each column, 7 cm from each other. Their length should exceed the height of the pillars by 20%.
Now you should fill the columns with concrete solution. It is optimal to use M400 cement, sand, small or medium crushed stone. To prepare concrete with your own hands, you should use a ratio of 1: 1.5: 3. Add 400 g of water per kilogram of cement. Concrete must be poured in several approaches.
After pouring the concrete, the columns are covered with film and left to dry and gain strength for 7-10 days. After this period, you can begin work on the construction of the bathhouse.
This technique is quite popular because it can significantly save time and money, and can also be done independently.
Brick columnar foundation
Preliminary preparation for the construction of this type of foundation is similar to the previous type. However, it is better to dig holes for posts by hand and make them a little wider to make it easier to work with.
A layer of sand 15-20 cm thick should be placed at the bottom of the recess and, after watering it with water, compact it thoroughly. A concrete base will subsequently be poured onto this sand cushion. For strength, reinforcing rods with a cross-section of 12-14 mm, cut to fit the size of the hole, are placed in the hole perpendicular to each other. The reinforcement at the intersection points is fastened together with wire with a diameter of 2-3 mm. Next, pour a 20 cm layer of concrete using M400 cement.
After a few days, when the concrete has hardened, brickwork can begin. The brick must be solid, for example, brand M-100, which is resistant to low temperatures and quite durable.
Although brick supports at first glance are quite strong, they can still be exposed to weather conditions at the seams and collapse over time.
Columnar foundation made of building blocks
To build this type of foundation, you will need industrial concrete blocks. Often, blocks with small voids or solid ones are used, the dimensions of which are 20 × 20 × 40 cm.
The advantages of this material are its strength and resistance to high loads. Basically, the principle of constructing a columnar foundation from blocks is similar to a brick one.
The differences in the technology of building a foundation from blocks to bricks are as follows:
- a thicker reinforced concrete base is required, about 50-70 cm, since the weight of the blocks is much greater than that of brick;
- as a cushion under the base, you can use not sand, but coarse or medium-fraction gravel, which will have a beneficial effect on the speed of moisture removal;
- starting to lay the first row of blocks, a small layer of fresh concrete mortar should be poured under it, serving as a cushion;
- in each subsequent row there should be at least two blocks, and in adjacent rows they are laid perpendicular to each other on a cement mortar.
If the foundation is laid on an area with uneven terrain, the depth of the block columns will be different, otherwise the finished structure may warp and the foundation will collapse.
Columnar foundation made of cement-sand mortar
A columnar foundation with reinforcement, made of concrete, is considered the most reliable and durable of all possible options.
Preliminary preparation and work with the soil are carried out according to the general scheme. To reinforce the columns, it is necessary to assemble a frame from reinforcement. To do this, vertically installed rods with a diameter of 12-14 mm are tied with thin wire to pieces smooth reinforcement, with a diameter of 6-8 mm, closed in circles or squares.
To pour a concrete column of a certain diameter, formwork is used. To assemble it, you can use an edged board, chipboard or any other suitable material. A significant disadvantage of such a foundation is its labor intensity and financial cost.
The bottom of the hole under the post is covered with a 10-20 cm layer of sand, which is carefully compacted. A roofing material or polyethylene film is laid on top of the sand cushion, which will become a barrier to retain moisture in the poured concrete.
Concrete solution grade 400 is prepared from cement grade M400, coarse sand, and fine or medium crushed stone. Mix the ingredients in a ratio of 1:1.5:3, adding water at the rate of 400 g per kilogram of cement.
The solution must be poured in stages, tamping the concrete every 30-35 cm of filling to expel the air.
When the pouring is completed, the columns need to be covered with film so that the solution gains strength and does not begin to crack. After a few days you can remove the formwork.
Concrete support pillars must be protected with a layer of waterproofing, and the free space in the pit must be covered with earth and compacted.
If you want to save time and money when pouring a columnar concrete foundation, you can avoid standard rigid formwork. An alternative in this case would be soft formwork made of roofing felt with fiberglass mesh. In this case, the recess under the post is made using a drill whose diameter exactly matches the size of the future support.
After preliminary filling with sand and laying a layer of waterproofing, roofing felt rolled into a ring is lowered into the hole. After this, a frame of reinforcement is installed inside, and further pouring of concrete is carried out similarly to the method with rigid formwork. In this case, after the concrete has gained strength, a ready-made support is obtained, covered with a waterproofing layer, so that further construction work can immediately begin.
Foundation with grillage
The construction of a foundation with a grillage is important if you are planning to build a basement floor, or if the entire structure of the bathhouse is supposed to be very heavy, made of brick, for example. A grillage is a reinforced strip structure that serves to tie together all the foundation columns into a single whole. This structure serves to evenly distribute the load over the entire area of the foundation.
To fill the grillage, you should build formwork from edged boards 20-40 mm thick, plywood, OSB or other similar material. Inside, the structure will be reinforced with a metal rod with a cross-section of 10-12 mm. To prepare the solution, you will need concrete grade of at least 150. It is optimal to use concrete grade 200, which consists of M400 cement, coarse sand and small or medium-sized gravel. The proportion for mixing concrete yourself is 1:2.5:4.5. Water is added at the rate of 400 g per 1 kg of cement.
When calculating the consumption of lumber for formwork, it is taken into account that the width of the grillage exceeds the size of the poured columns by 10 cm, and its height should be at least 30 cm.
When calculating the material consumption for formwork, take into account:
- The height of the grillage itself, to which you need to add another 20 cm so that the formwork rises slightly above the concrete.
- The thickness of the lumber itself must be added to the size of the future grillage.
- The entire total length of the grillage.
If you multiply all the parameters found, you can get the amount of required material, measured in m3.
Having purchased the required amount of material, you should assemble the formwork box. Holes should be cut in the bottom of the box corresponding to the dimensions of the installed support pillars, which should freely rise slightly above the bottom of the box.
Next you need to assemble the reinforcement frame. For it, reinforcement bars and transverse square clamps are used, which can be made from smooth thin reinforcement or from 6-8 mm wire. Clamps need to be installed every 30-35 cm along the entire length of the formwork. The reinforcement is connected to the clamps using knitting wire. The width of the frame should be such that there is 5-7 cm left to the walls of the formwork, and its length should be equal to the length of the entire future grillage.
In cases where the distance between adjacent pillars is too large, the formwork can be additionally supported by wooden supports installed clearly horizontally.
The reinforcing frame installed in the formwork must be fastened with pieces of reinforcement protruding from the support pillars.
If you have a concrete mixer truck equipped with the full volume of required concrete, then the formwork can be filled with mortar in one day. At the same time, do not forget to remove air from the concrete with a construction vibrator, a piece of reinforcement, or a regular shovel.
But if you have to mix the solution yourself, the process of filling the grillage may take several days. In this case, one part of the grillage is poured at a time, dividing it vertically into segments. When pouring each next section, the edges of the already hardened concrete are thoroughly moistened with water to achieve better adhesion of the concrete.
Once the entire formwork has been filled with concrete, it is covered with plastic film and left for several days to harden. After the concrete has completely dried, you can remove the formwork, obtaining a finished grillage.
Note that a columnar foundation for a bathhouse in any of the design options is stronger and more reliable than, say, a strip foundation. In addition, it requires less time and material costs and can be done independently.
The failure of strip foundations on rocky soil or areas flooded by groundwater has been proven in practice. This is where the columnar foundation is laid. The issue has been resolved, all that remains is to understand the principles of its creation.
Columnar foundation - how is it presented?
Externally, it looks like several rows of load-bearing pillars located relative to the load-bearing walls. That is, in places with significant load. In principle, this is typical for all types of foundations. In addition to load-bearing walls, pillars are placed at the intersection of external and internal walls. The foundation for the stove, based on pillars, is also prepared according to its size and schematic location. If according to the project a heater will be used for heating.
Over many years of practice, builders have determined the optimal distance between two supports to be 1.5–2.5 meters. To make the structure monolithic, and in order to strengthen the overall frame, for the purpose of subsequent installation of the basement row, above the ground, the supports are connected to each other with a grillage.
The most reliable option for columnar support is reinforced concrete pillars. They are durable and can withstand almost any weight of the structure. But given the relatively light weight of baths, even brick ones, the use of rubble concrete, stone, brick, steel and asbestos-cement pipes is allowed. These materials allow you to save on work. But before choosing them instead of reinforced concrete supports, the soil at the construction site is carefully checked for the presence of groundwater.
Technical aspects of admission
Regardless of what material is used for work, a frame bath 
built or brick, the arrangement of a columnar foundation is accompanied by the following factors:
- the columnar base is not conducive to arranging a basement;
- this type of foundation is less susceptible to freezing with all the ensuing consequences;
- the price of materials relative to the quantity required for pouring is much less.
In addition to the fact that a columnar base is preferable for light-weight buildings and is recommended for pouring on washable soil, there are a number of additional recommendations regarding structural design. For example, the total height of the foundation should not exceed 1.5 meters, and the shrinkage deformation, in relation to the most popular type of strip foundation, is 40% lower.
Conditions for the ineffectiveness of a columnar base
The first thing that indicates the impossibility of choosing such a foundation is complex design two floors or a bathhouse with a veranda. The explanation for this is the high overall 
weight. It is also better to abandon the columnar base in the presence of weak soils that are displaced horizontally. This feature of the soil will lead to displacement of the pillars and, although incomplete, deformation of the structure. “Weak soils” include peat bogs and places with large clay layers.
In order not to overpay for the purchase of material for pouring a columnar base, take into account the weight load on the foundation. Baths built from rounded logs or frame buildings are not very heavy, so the pillars do not need to be poured too deeply. This is explained by the fact that low temperatures in winter will affect the entire foundation, exceeding the kinetic load exerted by the weight of the structure. This will lead to cracking of the concrete and the appearance of a slope. The size of a non-buried foundation is 40–50 cm. At the same time, the depth of pouring the pillars, unlike, for example, a strip foundation for a bathhouse, should not exceed 70 cm, that is, not reaching the level of soil freezing. With the average value of this indicator across regions being 1 meter, it is enough to fill the pillars to a depth of 60–70 cm.
As already mentioned, heaving forces exert high loads on the columnar base and are directed mainly at the plantar and lateral surfaces. This force can be reduced by treating all posts with synthetic lubricants or bitumen-based mastic. In order not to rack your brains over the choice of means, and in order to save money, each post can be wrapped in roofing felt or other similar materials.
Foundation work - preparation
The initial process, during which the place for the foundation is prepared, is the most important. This is a recommendation not only for pouring the foundation, but also for building a bathhouse in general. There should be no debris on the site; the top layer of soil must be removed to a depth of 5 cm. Subsequently, this will further facilitate the work of laying drainage and sewage systems.
After this, the installation location of the pillars is marked. Initially, you need to outline their filling at corner joints and at the junction of internal partitions, only after that 
you can calculate the distance according to the standard (1.5–2.5 meters) relative to other supports. If it is not possible to meet these indicators, and the distance exceeds the stated standards, then it is necessary to reconsider the location by adjusting the parameters. Remember - installing supports closer than 1.5 meters is also unacceptable, this can lead to a weakening of the bearing capacity of the soil.
Instructions for pouring pillars
When the work site is ready and the locations for installing the supports have been identified, we begin digging holes for them. This is done manually or with specialized equipment, the main thing is to maintain the depth of the bookmark. The floor width of the pit should be 10 cm larger on each side. This reserve is necessary to create a reinforcement frame. It is worth recalling that this must be done under the condition of monolithic filling. If a columnar foundation is installed under a light-weight log bathhouse, then it is better to make it from ready-made reinforced concrete supports.
The pit is ready, add a sand and gravel cushion to the bottom. We water it all with water and tamp it down a little. Now you need to insert a reinforcement frame, welded in advance to size, into the hole. It will be inconvenient to install the harness here, so it is better to prepare it in advance, according to the height of the fill. The frame is thoroughly trimmed horizontally and vertically using appropriate devices. Afterwards, according to the plan, the formwork is installed or its use is omitted due to the design features of the bathhouse.
Next, the frame is wrapped along the contour with roofing material, taking into account that the solution will be poured inside it. The edges are fastened with a stapler. Now all that remains is to pour the solution and, if possible, expel air from the layers to reduce the possibility of cracking. The base is ready. All that remains is to let it gain strength and you can begin building any bathhouse, even a brick one.
Considering the filling option as the most difficult and worthy of attention, 
It is necessary to highlight several points regarding its characteristics and design features.
- A columnar foundation for a bathhouse, made by pouring a reinforcement frame, can last up to 150 years.
- In order for the building to stand for a long time and reliably, it will be enough to prepare a shallow version, which will save on material.
- If the building does not have a basement, then there is no need to make formwork and raise the foundation above the soil. You can protect the basement level with roofing felt.
That's all the tricks for laying a columnar base for a bathhouse. If everything is done correctly, the foundation will be as strong as possible. And the option that, relative to such a basis, it is as simple as possible to carry out water supply in the bathhouse, speaks of its attractiveness for those who do everything with their own hands.
Almost all happy owners of private houses, cottages or country houses would like to have a separate bathhouse on their property. To build it, you can use the services of professional builders or build a bathhouse yourself.
The basis for the strength and durability of every building is undoubtedly the foundation. Often, wooden material is used to build a bathhouse - logs or timber, which makes the construction quite light. That is why it is advisable to build a bathhouse on a columnar foundation, which consists of support pillars buried in the soil made of various materials. Such supports can be mounted from wood, brick, stone, pipes, foundation blocks, reinforced concrete.
Columnar foundation - diagram 
Before starting work, it is necessary to clean and level the site for future construction. To do this, we remove the top layer of soil (about 30 centimeters) under the planned building along with all the vegetation.
Then it is necessary to level out all the holes and irregularities as much as possible, and if the soil is clayey, add sand and gravel.
Next, we transfer the plan of the bathhouse directly to the land plot, using a tape measure, a building level, ordinary wooden or metal pegs and construction thread to mark the axes. If the site is located on an area that has a significant difference in height between the sides, then to determine the height of the foundation pillars, it is advisable to use the help of a professional and level the surface. This is a guarantee that the future bath will not have distortions.
Excavation
Regardless of the choice of material for installing columnar supports, all foundations of this type are mounted according to a similar principle (except for the option with a grillage). This also applies to excavation work, before starting which you need to determine the type of soil, proximity to the surface of groundwater and the depth of its freezing.
These factors directly affect the installation depth of the support pillars. To determine the type of soil and groundwater level, you need to dig a hole at least 1-1.2 meters deep (optimally). If there is no groundwater at this depth, and the soil is not heaving - freezing, then this depth is quite sufficient for a columnar foundation of a bathhouse.
Otherwise, you need to dig to a dense, incompressible layer of soil, focusing on the following indicator: freezing depth + 40 centimeters. It must be remembered that heaving soils include those that contain clay. And the more it is contained, the more prone the earth is to freezing. If these conditions are not met, then under the influence of water or sub-zero temperatures the foundation may not only crack or deform, but also completely collapse.
Columnar foundation supports must be located at the corners of the building, at the intersection of walls, along the entire perimeter and under the partitions every 1.5-2.0 meters, depending on the total weight of the structure. Holes for supports can be dug with a shovel, or you can use a special hand-held cone-shaped drill of the required diameter, thanks to which it is possible to obtain the most even holes.
Based on what material will be used for the construction of the columnar foundation, the required diameter of the holes is determined, which should be 7-10 centimeters larger than the following parameters:
- for pillars made of brick and stone, the optimal size is 50x50 centimeters;
- for pillars made of rubble stone - 60x60 centimeters;
- for asbestos-cement pipes Ø200 mm;
- for reinforced concrete supports 30-35 centimeters is enough;
- for intermediate ones it is 25-30 centimeters.
We pour about 20 centimeters of sand into the bottom of each prepared hole, add a little water and tamp it thoroughly, thus obtaining the desired sand cushion. At this point, the preparatory and excavation work is completed. You can begin directly constructing a columnar foundation from the selected material.
Columnar foundation made of pipes
The best option for a columnar foundation of a bathhouse is metal or asbestos-cement pipes Ø200 millimeters, which can be easily cut with a grinder into pieces of the required length. It should be taken into account that a pole made of a pipe should protrude above the surface by approximately 0.4 meters.
| Name of product | Weight of 1 pipe, kg | Internal external diameter, mm | Price 1 p/m, rub. |
|---|---|---|---|
| BNT 100*3.95m | 24 | 100/118 | 102,97 |
| BNT 150*3.95m | 36 | 141/161 | 165,79 |
| BNT 200*5m | 85 | 200/222 | 319,99 |
| BNT 250*5m | 125 | 238/266 | 392,76 |
| BNT 300*5m | 162 | 292/320 | 617,46 |
| BNT 400*5m | 279 | 365/407 | 958,66 |
| BNT 500*5m | 430 | 456/508 | 1732,51 |
Pipes must be protected from moisture and other negative factors. To do this, you need to make waterproofing - wrap the surface of the pipe with roofing material with bitumen, lining waterproofing materials, or treat it with special mastics.
The prepared pipes are carefully and evenly lowered into each hole.
The gap between the pipe wall and the soil is filled with previously dug earth or sand and gravel (layer thickness 40-50 centimeters), which it is advisable to compact thoroughly.
Reinforcing rods Ø12-14 millimeters should be inserted into the middle of the installed pipes at a distance of 7 centimeters from each other, which act as a reinforcing frame. Since the reinforcement must protrude above the finished pillars, its length should be 20% greater than the size of the pipe.
Having carried out these preparatory work, you can begin pouring the foundation pillars. The best option is concrete grade M400. It can be ordered from specialized enterprises or made yourself using a concrete mixer. When making it yourself, it is enough to use M400 cement, coarse sand, fine and medium gravel, which must be mixed in a ratio of 1: 1.5: 3. The required amount of water is 0.4 part of the amount of cement taken.
The process of pouring the concrete mixture itself occurs in several stages (see table).
| Work order | Illustration |
|---|---|
| concrete is poured inside the installed pipe to a third of its height |
|
| the pipe rises, which allows the concrete to form a kind of cushion, and then is pressed into this base |
|
| Subsequently, we continue to pour concrete into and around the pipe step by step, compacting it every 0.3 meters with a deep concrete vibrator, and in its absence, a reinforcing rod can be used. This is necessary to get rid of air bubbles and improve the quality of concrete. |
|
We cover the piles made in this way with film and let them stand for 7-10 days. During this time, the concrete gains the necessary strength and the construction of the bathhouse can continue.
This method of constructing columnar foundations is one of the most popular due to its high reliability, relative cheapness, and speed of installation with minimal skills.
Prices for asbestos-cement non-pressure pipes
asbestos-cement non-pressure pipes
Preparatory and excavation work before arranging a columnar brick foundation is similar to working with pipes. But for the convenience of the master, holes for future pillars will not have to be drilled, but dug manually or using machinery, which is much faster, but also more expensive. At the same time, do not forget to slightly increase the volume for ease of operation.
We fill the bottom of the prepared pit with a fifteen- to twenty-centimeter layer of sand, which we compact, forming a sand cushion. On top of it it is necessary to pour a concrete base, reinforced with a mesh of reinforcement. To make the mesh, we take reinforcing bars with a cross-section of 12-14 millimeters, cut to the parameters of the pit. We lay them perpendicularly, forming square cells, the intersections of which are fastened with thin knitting wire with a diameter of 2-3 millimeters. For ease of knitting, you can use a special hook, which is worth purchasing at a hardware store. Thickness concrete base(M400) together with the reinforcing mesh should not be more than 20 centimeters.
Columnar brick foundation - diagram
After giving the concrete a few days to gain strength, you can proceed directly to the brickwork. It is necessary to take into account that hollow bricks are completely unsuitable for this. It would be optimal to use solid ceramic bricks (for example, M-100), which have the necessary strength and resistance to low temperatures.
When making brickwork, it is advisable to check each row with a level. This will allow you to get an even column. For greater strength of the pillars, you can lay a mesh of reinforcement after 3-4 rows of bricks. We bury the brick support of the foundation 15-20 centimeters above ground level and protect it with waterproofing material - mastic or roofing felt with hot bitumen. After 5-7 days, we fill the finished brick pillar with earth, which we compact thoroughly.
Despite the popularity of this columnar foundation, it has its drawbacks. The seams between the bricks make such a support quite fragile and under the influence of unfavorable factors it can be destroyed.
Brick prices
For its production, industrial concrete foundation blocks are used. Most often we use a solid block or with minor voids measuring 20x20x40 centimeters.
This is a durable building material that can withstand significant loads. A columnar foundation made of blocks is mounted similarly to brick supports, taking into account some differences:
- due to the greater weight of the blocks, the thickness of the monolithic reinforced concrete base on top of the sand cushion varies from 50 to 70 centimeters;
- It is permissible to make it from coarse and medium fraction crushed stone instead of sand bedding. This helps remove any moisture present;
- before installing the first row of blocks, it is necessary to make a cushion of mortar, on which the building material should be installed;
- the row being installed must consist of at least two blocks. Each subsequent one is installed perpendicular to the previous one and fastened to it with ordinary cement mortar for masonry.
The last row of blocks is installed 20-30 centimeters above the ground and covered with waterproofing material to protect the seams and the blocks themselves from moisture and low temperatures. temperature regime, which together can lead to the destruction of a columnar foundation of this type. When laying blocks on the surface, you need to carefully control their location relative to the marked axes of the future bathhouse building. We fill the gap around the mounted block supports back with previously dug soil, which we also tamp.
Block foundation - photo
Laying blocks on a sloping area requires special attention. Under no circumstances should block supports be laid at the same depth. This can lead to subsequent distortion of the bathhouse and destruction of the columnar foundation.
Concrete columnar foundation
A reinforced monolithic columnar concrete foundation is considered the strongest and most reliable.
To manufacture it, we carry out preparatory and excavation work in accordance with general technology. From reinforcement Ø12-14 millimeters we make round and square frames (we use 3 or 4 rods, respectively) of the required length, taking into account the protrusion above the post by 15-20 centimeters. To do this, we connect the rods with thin wire to round or square rings bent from smooth reinforcement Ø6-8 millimeters.
It is possible to fill a foundation pillar of the required size only with the help of formwork, which should be made from edged boards, wood chips and other suitable materials. However, this method is quite time-consuming, labor-intensive and financially expensive.
At the bottom of the prepared pit, pour a layer of 10-20 centimeters and compact it with a sand cushion, on top of which we lay roofing material or polyethylene, which is necessary to retain moisture in the poured concrete.
We immerse the assembled formwork into the hole and install a reinforced frame there.
Columnar foundation - formwork and reinforcement diagram
We pour concrete grade 400 into the formwork, which is prepared from cement grade M 400, coarse sand, fine and medium gravel, mixed in a ratio of 1:1.5:3 with water in the amount of 0.4 parts of the cement used.
Every 30-35 centimeters of pouring we tamp the concrete, removing air.
We cover the finished support with film and let it sit for several days, after which we remove the formwork from the hardened concrete.
We cover the finished supports with waterproofing materials and fill the sinuses with previously dug earth.
To reduce costs and time when arranging a columnar foundation for a concrete bathhouse, instead of rigid formwork, you can use permanent soft formwork, which is a roofing material with a fiberglass mesh. In this case, holes for the support must be made using a drill of the appropriate size. Having cut the roofing material to the required length, twist it and install it in the prepared hole. At the same time, a sand cushion and a bottom insulating layer are also necessary. Next, we install the reinforced frame and pour concrete as with removable formwork. Using this material, we obtain a finished pile, immediately covered with waterproofing material. And immediately after the concrete gains strength, the next stage of work can be carried out.
Photo – pouring process 
Prices for roofing material
roofing felt
Video - Pouring a columnar foundation
When constructing a heavier bathhouse building (for example, made of brick) or if you want to equip a basement, you can mount a columnar foundation with a grillage. This is a monolithic reinforced concrete strip structure that connects the top points of all foundation elements buried in the ground.
To fill the grillage, you will need formwork material: edged board with a thickness of 20 to 40 millimeters, plywood, OSB or other similar building material. As well as reinforcement with a cross-section of 10-12 millimeters and concrete of at least grade 150. Most often, grade 200 concrete is used to fill the grillage, and if you make it yourself, you need to mix M400 cement, coarse sand and medium or fine crushed stone in a ratio of 1:2, 5:4,5.
Let's calculate the amount of lumber for formwork. It must be taken into account that the height of the grillage should be at least 0.3 meters, and its width should be 10 centimeters greater than the width of the manufactured columnar supports.
- We determine the immediate height of the grillage and add another 0.2 meters to it since the height of the formwork must be greater than the level of concrete poured into it.
- We fix the thickness of the formwork material in meters.
- We measure the total length of the future grillage.
- We multiply all the obtained parameters together and get the required amount of material for formwork in cubic meters.
From the prepared lumber we knock down the formwork box. In its lower part, holes should be cut for the previously made pillars, which should rise slightly above the lower part of the formwork.
Video - Installation of formwork
From reinforcement rods it is necessary to make frames with transverse square clamps, which can be bent from thinner smooth reinforcement or from wire Ø6-8 mm. They will give the necessary strength and reliability to the structure. Every 30-35 centimeters we connect clamps and reinforcement rods with knitting wire in an amount equal to the entire perimeter of the grillage. We calculate the size of the frame in such a way that there is 5-7 centimeters from it to the walls of the formwork.
If the finished foundation pillars are located at a considerable distance from each other, then for reliability you can strengthen the formwork with wooden supports, which must be installed strictly horizontally.
Before pouring concrete into the formwork box, we will install a reinforcing frame, fixing its lower part to the reinforcement protruding from the columns.
Video - Columnar foundation. Formwork, reinforcement, pouring
If pouring is done from a concrete mixer truck, then pour the entire concrete mixture at once, removing air with a construction vibrator, a reinforcement rod, or simply using a shovel.
If you have to mix the concrete yourself and the pouring takes several days, then:
- at one time we fill in part of the grillage, divided vertically, not forgetting to remove the air;
- Before pouring the next part, the edge of the finished block with already hardened concrete is generously moistened with water.
Fill the formwork completely with concrete mixture, cover it with film and let it stand for several days. Then we carefully remove the wooden box and our hanging grillage is ready.
It is worth noting that regardless of the material used to construct the columnar foundation, this version of the foundation for a future bathhouse is more reliable than the traditional strip one, and at the same time is much cheaper (almost half).
Video - Pile-grillage foundation
Video - Nuances of constructing a pile-grillage foundation
If you build a columnar foundation for a bathhouse with your own hands, provided that the soil characteristics are satisfactory, this will ensure minimal construction costs. This reliable choice for areas with soil that is not prone to subsidence and swelling. This type of foundation consists of pillars buried in the soil made of different materials.
The columnar foundation is used for bathhouses made of logs and timber, and panel buildings. The frame structure of the bathhouse can also be installed on such a foundation. This is an ideal and economical option for lightweight wall structures and small buildings. The cost of material resources and labor costs for a columnar foundation is 1.5-2 times lower than the cost level for constructing a strip foundation.
A tangible result when constructing a columnar foundation for a bathhouse with your own hands will be real savings in money.
Columnar foundation structures
Let's take a closer look at how to make a columnar foundation for a bathhouse with your own hands and which foundation design to give preference to.
The foundation consists of a number of pillars located along the axes of all load-bearing walls, at the corners and intersections of the walls. The pillars are placed under internal partitions and other massive structural elements, such as a sauna stove. The best distance between pillars is 1.5-2 m.
Construction of a load-bearing building structure from various materials
Initially, the question arises of choosing a suitable and available material. The columnar foundation is made of:
- From wooden pillars - logs with a diameter of 200 or maybe timber using insulating materials and treatment with antiseptics. Least durable. Practical if the structure is being built for a period of up to 10 years;
- Made of brick, the size of the columns in plan is 380x380, stone 500x600;
- Made of concrete blocks 400x400;
- From steel pipes or asbestos-cement, filled with concrete;
- Made of monolithic concrete 400x400.
A bathhouse on a columnar foundation is erected on a prepared site, the following is given step-by-step instruction its buildings.
Preparation of work
First, the site is cleared of debris and graded. The top plant layer, at least 30 cm thick, is cut off. If necessary, the site is drained to drain the water. On clay soil, gravel-sand preparation of the required thickness is arranged with leveling. If there is a large difference in height between the sides of the site, it is necessary to level the surface to avoid distortions of the walls.
The plan of the bathhouse is transferred to the land using a tape measure, level, stakes and twine, marking the axes of the building.
Excavation
The laying depth of non-buried columns, as a rule, is from 40 to 50 cm; it should be less than the soil freezing depth by one third of the value.
It is typical for a recessed columnar foundation that the supports are laid to a depth less than the freezing depth by 50-70%. So, if the soil has a freezing depth of 1.2 m, then the laying depth should be from 60 to 80 cm.
Holes for supports are dug manually or using a drill. Their depth is greater than the calculated backfill depth by the thickness of the sand bedding. The cross-sectional size of the pits is made larger by 10-15 cm for ease of installation of the reinforcement frame and formwork.
The bottom of each pit is filled with sand, moistened with water and then compacted.
Installation of a non-buried supporting structure Basic principles of construction
Regardless of the chosen material, the columnar foundation is installed almost according to the same scheme - a hole of the required depth is prepared, filled with 15-20 cm of sand, which is compacted after pouring with water, then a support is placed. Let's look in detail at how to install poles made of various materials.
Wooden foundation
The construction of a lightweight building, such as a bathhouse, allows the use of wooden poles. For the “chair” posts, the lower part of the log is used - the butt with a diameter of 25-30 cm. It is better to use pine or oak. The size of the pit should be 1.5 times the diameter of the support. Preparation for installation consists of burning the lower part of the support with a blowtorch, treating it with an antiseptic solution and coating it with bitumen in accordance with building codes. These measures will extend the life of the tree. As a rule, pine supports last up to 10-15 years, and oak supports up to 25-30 years.
When building a bathhouse, one of two methods of constructing pillars is used - non-buried, in which a wooden pillar, the height of which is 70 cm, rests on a wooden base and is buried with a pillar height of 1.2-1.4 m. In the latter case, it is better if the support is installed on a concrete preparation in a hole for reliable fixation, followed by backfilling with crushed stone and soil.
Brick foundation
The installation of brick pillars dictates the condition of durable and high-quality masonry in order to avoid destruction of the pillars and deformation of the walls of the bathhouse itself. The cross-sectional area of the pillar consists of 4 bricks. The pillars are laid to a depth of 0.5 to 0.7 meters The service life of a brick pillar foundation can be 50-100 years, depending on factors such as climatic conditions, soil characteristics, brick quality and masonry strength.
It is important to use only solid red fired brick, which has the least properties to absorb moisture and good strength. Sand-lime brick is completely unsuitable for this purpose.
A sand and gravel cushion up to 20 cm thick is placed along the bottom of the pit, poured with liquid cement mortar and laid with a steel mesh made of wire with a diameter of 3-4 mm or reinforcing bars.
After completion of the masonry, waterproofing is installed on the surface of each pillar, for which roofing felt and bitumen are used, preventing contact of the masonry with the ground.
The sinuses are filled with soil or crushed stone and compacted.
Foundation made of concrete blocks
Scheme of a recessed and shallow foundation on a sand cushion An obvious advantage of this type of foundation is the speed of its installation. Ready-made concrete blocks are used. These are solid blocks, or with small voids, which have dimensions of 20x20x40 cm. The quantity is calculated based on the design of the future construction.
The foundation of blocks is installed in the same way as brick pillars. Each row consists of at least two blocks. The next row is laid perpendicular to the previous one on masonry cement mortar and so on until the required height is reached. As a rule, 20-30 cm from the surface of the area is sufficient. Then work is carried out to waterproof all surfaces of the structure using roofing felt and bitumen mastic. The seams need to be treated especially carefully. Need to finish backfill sinuses with previously removed soil.
Pipe foundation
Carrier building construction on asbestos-cement pipes with a diameter of 200 mm A convenient type of columnar foundation is considered to be metal or asbestos-cement pipes with a diameter of 200 mm. Their advantage is that they can be easily cut to the required length using a regular grinder with discs for cement or metal. The pipe should protrude approximately 40 cm from the ground surface.
Pipe surfaces must be waterproofed. It is done either by coating with bitumen or by covering with roofing felt on bitumen mastic in order to avoid corrosion and the negative effects of external factors.
Each pipe is lowered into a drilled hole with a diameter of 250 mm and a depth of approximately 1 m. Crushed stone is poured into the bosoms to a level of 40 cm from the bottom of the hole. It is advisable to insert reinforcing bars with a diameter of 12-14 mm into the pipe for strength.
After the preparatory work, you need to fill the pipe cavity with grade 400 concrete and compact it. Then fill the space between the pipe and the walls of the pit with small crushed stone or excavated soil.
An important note is that you need to cover the concrete columns with film and let them sit for 7-10 days to gain strength.
Monolithic concrete foundation
This type of foundation is very common and most reliable. The foundation, made according to the technology, has a service life of about 150 years.
It is enough to pour a shallow foundation under a wooden bathhouse.
Initially, you need to set up the formwork, which is prepared from edged boards. Then arrange a sand cushion and pour it with water and tamp it down. Next, you need to install the reinforcement cage, fill it with M400 concrete and compact it with a vibrator or a piece of steel reinforcement. The formwork can be removed after 2 weeks, depending on weather conditions, when the concrete gains strength.
After the concrete has gained strength and waterproofing work has been carried out, the cavity of the pits is filled with soil. You can begin installing the walls of the bathhouse, installing beams, roofing, and installing the floor.
What is the best way to make a floor on this type of foundation?
In order to protect the floor in the bathhouse from cold air and snow, a special wall is usually made of brick or concrete between the pillars with technological openings for communications and ventilation. This wall is called a fence. It serves to enclose the underground space; later, additional insulation of the space can be carried out with polystyrene foam. The question of how to close it is solved when covering the facade of the entire bathhouse.
The problem of organizing drainage in a bathhouse must be solved at the stage of constructing the foundation. This is relevant if it is planned to install a pourable floor. The device of the pouring floor has an extremely simple design, in which a ladder is arranged for draining water.
Watch a video on how to prevent the pillars of a supporting structure from rising due to winter soil heaving
The construction of any building or structure begins with the arrangement of the foundation. The same applies to the bathhouse. If your site is located on rocky terrain or the area is often flooded, then a columnar foundation for a bathhouse is exactly what you need to complete the first stage towards the construction of this building. In our article we will tell you how to build such a base, what options it may have, and what materials you will need for the work. In addition, a step-by-step guide to performing the work will help you make your own foundation as correctly and quickly as possible.
Peculiarities
First, let's figure out what this type of foundation is. Externally, the entire structure looks like a grid of columns, which are located with a certain step under the load-bearing walls and nodal points of the future structure.
Important: columns are installed along load-bearing walls, at the places where they intersect and where columns are located, as well as under internal partitions and heavy structures, such as a stove or fireplace.
The optimal pitch of the posts is 150-250 cm. In order for the structure to acquire additional rigidity, the posts are connected with a grillage. It will not only serve as a connector between the pillars, but will also serve as a support for the walls and the basis for arranging the base.
The choice of material for making posts depends on the type of soil and the weight of the future structure. So, the columns can be brick, concrete, reinforced concrete, rubble concrete. There are also steel, stone, wooden poles or products made from asbestos-cement pipes.
Before choosing a columnar foundation for a bathhouse, it is worth considering several points:
- The entire structure must be fairly light (wooden or frame).
- The building should not have a basement.
- If the site is on a slope and the height difference at the construction site is more than 2 m.
- Weak mobile soil that is subject to horizontal loads.
- On clay and peaty soils, it is better not to make columnar foundations.
- Such foundations are not suitable for massive buildings made of artificial and natural stone and concrete.
Advantages and disadvantages
A columnar foundation has several advantages over other types of foundations:
- Such bases are practically not susceptible to heaving under conditions of severe soil freezing.
- The draft of such a base is significantly lower than that of a strip structure.
- If, according to calculations, the width of the strip base is more than 1.5 m, then it is much easier and cheaper to make a columnar version of the foundation.
The only drawback of such a base is associated with its low load-bearing capacity. That is, it can be constructed for buildings with light weight, which do not significantly load the foundations. For example, such a foundation can be made for wooden and frame houses, but it is not suitable for brick, concrete and stone buildings. That is why a columnar foundation is an ideal foundation for a wooden bathhouse.
Design nuances
All columnar foundations can be divided into two types:
- Recessed. The bottom of such foundations should be 0.5-1 m below the freezing point of the ground in the region. This option is suitable for clay soils and can also be used in conditions of high groundwater levels.
- Shallow foundations They sink into the ground by 0.4-0.7 m. They are suitable for soils with high bearing capacity.
Despite the fact that a wooden bathhouse is a lightweight structure, on heaving soils it is better to use a buried columnar foundation. The thing is that in the case of using a shallow foundation with a small weight of the entire structure, heaving forces will affect the foundation more strongly than the weight of the building. This can lead to deformation of the structure and the formation of cracks.
Depending on the material used, the optimal cross-section values for the columns are as follows:
- stone pillars can be made with a cross section of at least 50-60 cm;
- brick columns are laid out with a section of 380x380 mm;
- monolithic structures are poured with dimensions of 400x400 mm;
- wooden poles are usually made from logs with a diameter of at least 0.2 m.
To correctly determine the dimensions of the pillars, it is necessary to perform an engineering calculation, which takes into account the following indicators:
- the weight of the entire structure;
- geological conditions and soil composition;
- soil freezing depth (the bottom of the pillars should be below this mark);
- height of groundwater and seasonal changes in this level. It is best that the pillars do not reach the groundwater level.
Options for columnar foundations for a bathhouse
For such a small structure as a bathhouse, you can use several options for constructing a columnar base:
- support-columnar base made of blocks;
- columnar variety with grillage;
- pipe base;
- bored foundation.
Let's consider each of the listed options in more detail.
Support-column base made of blocks
This is the simplest and most affordable option, which is made from ready-made reinforced concrete blocks measuring 0.4x0.2x0.2 m. Based on these standard sizes, you will need 4 blocks for one support.
Such posts are installed at the corners of the building. They are also installed at intersections of structures and under heavy walls. If a stove is built in the bathhouse, then a foundation must also be made under it.
Important: the optimal column spacing is one and a half to two meters.
The work is carried out in the following sequence:
- After laying out the terrain in the right places, they dig holes of the required depth for the pillars.
- Sand is poured into the bottom of each hole, moistened with water and compacted.
- After this, you can begin laying the blocks. The elements are connected to each other using a viscous cement mortar.
- Be sure to waterproof the pillars around the perimeter. You can use roofing material for this.
- After the columns are erected, wooden beams are laid to connect the entire structure. Before laying them, the pillars are covered with two layers of roofing material to insulate the first crown or connecting beam from moisture.
- Before laying the first row of bathhouse logs, the wooden beams must be covered with waterproofing so that moisture from the base is not transferred to the walls.
Columnar base with grillage
Thanks to the grillage, the entire base structure will be combined into a single structure, which will make it even stronger. The above-ground part of the bathhouse is installed on the grillage. It is made of beams that are laid on poles and attached to them. This option is more suitable for baths made of piece materials - foam blocks, bricks. When making a wooden structure from a log or timber, the grillage functions are assigned to the first crown or row.
The grillage can be used with different types columnar bases. At the same time, it can be high and low:
- a low grillage is located below the earth's surface;
- a high grillage is installed on top of the tables.
Important: to construct a grillage, you can use reinforced concrete beams, rolled profiles, metal structures and wooden beams.
Pipe base
To make the pillars, you can use steel or asbestos-cement pipes of a suitable diameter (usually 20 cm is enough). These pipes will serve as a column and permanent formwork at the same time.
For greater strength, a reinforcement cage is installed inside the hollow pipe and filled with concrete grade of at least 200 (without additives). Installation work is carried out in the following sequence:
- After laying out and digging holes, hollow pipes are installed. The pipes are leveled in a strictly vertical position and fixed.
- A reinforcement frame is placed inside each pipe.
- Then the pipe is filled 1/3 with concrete. After vibropressing, concrete is poured into the rest of the pipe.
Important: instead of special vibropressing, you can use a regular metal pin. They should pierce the solution after pouring, thereby getting rid of air bubbles/
- Then you can fill and compact the soil in the hole around the pipe.
Bored foundation
A bored foundation is a cross between a pile and columnar foundation. The essence of the method is as follows: using a drill, a well is drilled into which concrete is then poured. The main advantage of such a base is its high load bearing capacity. It can withstand not only a wooden bathhouse, but also a more permanent structure. The only drawback is the high price and complexity of the work.
The sequence of work is as follows:
- After staking out the terrain, wells are drilled in the right places. The optimal well diameter is 30 cm. And the penetration depth should be 15-20 cm below the freezing mark.
- To improve the performance characteristics, the well walls are treated with a special solution.
- A reinforcement frame made of interconnected reinforcement bars is laid inside the penetration.
- After this, you can pour concrete in several stages, followed by compacting each layer.
- All subsequent construction work on the construction of the bathhouse can be carried out after 28 days (the period for complete hardening of the concrete).
