How to build a foundation for a bathhouse from timber with your own hands

November 23, 2021 Stroyexpert Home page » Foundation » By construction project

Foundation for a bathhouse made of logs

Any construction begins, of course, with its foundation. The foundation of a home steam room must be thought out to the smallest detail. The bath foundation is usually made of one of two types - strip or columnar. Only based on certain parameters should you finally choose the foundation for a log bath.

What influences the choice of foundation

This is not an idle question, because the foundation determines the load-bearing capacity of the entire structure. Therefore, it must be resolved before construction begins, because after the completion of construction work, adjusting something will be a big problem.

It is necessary to add the fact that the foundation structure allows the entire building to shift under the influence of various loads without violating the integrity of the structure. Therefore, before placing a foundation for a bathhouse, you need to choose its type and the materials from which the structure will be built. But this is just a consequence, and the reasons for the choice are:

• type of soil at the construction site;
• soil freezing level;
• ground water level.

To be more precise, these are three pillars that are taken into account when choosing a foundation. But there are a number of other minor factors that need to be taken into account. We'll talk about this below.

Types of soils for construction Source stroyfora.ru

Calculation instructions

To determine the size of the base of the bathhouse, it is important to take into account the weight of the future structure and the distinctive features of the soil.

For calculations you will need to use three formulas:

1. Depth H = h * kT * kL h – standard for soil freezing in the region; kT – coefficient of soil heating during active heating of the steam room (0.7 - 1); kL – coefficient value of frequency of use.
2. Base size A = B (C * D) A – base width; B – weight of the structure, taking into account the roof, stove and number of visitors; C – soil resistance. D – base length;
3. Number of pillars or pile supports X = B (C * Z) X – number of piles; B – weight of the structure; C – soil resistance; Z is the cross-sectional area of ​​the pile.

Types of foundations for a bathhouse

There are three types of foundation structures that are installed under baths:

• pile;
• tape;
• slab.

Let's look at them separately and determine which foundation for a bathhouse is better.

Pile

This variety is built only on soils classified as “weakly water-saturated.” That is, these are soils with low bearing capacity, plus the moisture concentration in them is quite high.

The pile foundations themselves are of three types, which differ from each other in the materials used for construction and the method of installation:

• Piling and driving. This technology is driving reinforced concrete piles into the ground using special equipment. Sometimes even steel pipes are used as piles, which are then filled with concrete. Previously, they even used logs for this. Concrete piles are an excellent option, guaranteeing high strength of the base, plus long-term operation. But for small-sized baths this option is very expensive, so private developers rarely use it.

Pile-driven foundation Source zen.yandex.ru

• Screw piles. This variety appeared on the Russian construction market relatively recently. This is a new technology based on steel piles, which are a pipe with a screw at the end. They are simply screwed into the ground to the required depth. By calculating the number of elements, you can build a foundation even for a house of several floors. But screw piles are rarely used for baths due to the high price of the material.

Screw piles made of steel pipe Source idealnii-dom.ru

• The third option is popularly called a columnar foundation due to its similarity to pillars. There is no such term in construction science. They are constructed in the form of a monolith, pouring concrete solution into formwork or pipes: steel, plastic or asbestos. Or they raise a prefabricated structure from piece material: brick, concrete blocks or stone. Both the first and second options are considered low-cost, so they are used more often than others as the basis for a bathhouse.

Online foundation calculator

To find out the approximate cost of a columnar foundation, use the following calculator:

Columnar foundation made of concrete blocks Source vash-fundament.ru

See also: Catalog of bathhouse projects presented at the “Low-Rise Country” exhibition.

Let's look at how to make a foundation for a bathhouse in the form of free-standing pillars.

Columnar foundation construction technology

Before making a foundation for a bathhouse from concrete pillars, it is necessary to determine their number. If the bathhouse is a small building, for example, 6x6 m, then the piles are erected at the corners of the building and at the intersection of the internal and external walls. Of course, a lot will depend on the material from which the bathhouse is constructed. The greater the weight of the building, the more support pillars will have to be constructed.

Here is the sequence of operations:

• in places where supports are constructed, round or square holes are dug;
• a cushion of medium-fraction crushed stone is filled in;
• formwork is installed in them;
• a reinforcing frame made of steel reinforcement with a diameter of at least 10 mm is inserted inside;
• Concrete of the classic recipe is poured.

The main task of the work contractor is to bring all the pillars to the same height so that their ends are in the same horizontal plane. This is not always possible even for masters, so leveling is done with a grillage. The latter is either a concrete structure in the form of a tape connecting the pillars, or wooden beams laid on supports and interconnected

Pile foundation of columnar type with grillage Source grisstroy.ru

A few words about formwork. If the support posts have a round cross-section, then you can install pipes and fill them with concrete mortar. If the soil on the site is clayey and strong, then holes with a diameter of 20-30 cm are drilled in the ground, for which a drill is used. Roofing felt rolled into a cylinder is placed in them, and a reinforced frame is inserted into it and concrete is poured. In this case, the roofing material will act as a waterproofing device. For the above-ground part of the foundation, formwork is installed in the form of the same pipes.

If you plan to pour rectangular pillars, then boards that are knocked into a box are used as formwork. Everything else is done as in previous cases.

Attention! It is not recommended to construct a columnar structure on moving soils. The reason is that over time the pillars will lose their position relative to the vertical, which will affect the strength of the bathhouse as a whole.

Formwork for a columnar foundation structure Source pinterest.com
See also: Catalog of companies that specialize in the repair and design of foundations and the design and construction of baths.

Tape

This is the most effective base option for any structure, because it is a tape laid around the perimeter, on which all the external walls of the building rest. But this is also the most expensive and labor-intensive option for the foundation structure. Of course, everything will depend on the size of the foundation structure and whether it will be reinforced or not.

Today in construction, strip foundations of various types are erected:

• monolithic;
• made;
• combined.

The first is concrete poured into the formwork. The second is a structure made from ready-made block materials: concrete blocks of standard sizes, special products for foundations, bricks and stone. The third is the use of both monolith and blocks.

The monolithic variety is the most reliable design. It can be erected on any soil, on any terrain, on sloped areas. At the same time, concrete can be poured to any depth, which is an important characteristic for many regions. At the same time, builders also use shallow structures, which are often poured under bathhouses. This is when the depth of installation in the ground does not exceed 30 cm.

Prefabricated strip foundation Source beton-stroyka.ru

Let's look at how to properly make a strip foundation for a bathhouse with your own hands step by step. In principle, the technology is not much different from pouring pillars. Nevertheless:

• a trench is dug to the required depth, taking into account the width of the foundation strip, which is included in the house design;
• sand is poured onto the bottom and compacted; the thickness of the compacted layer is at least 30 cm;
• crushed stone is poured in, which is also compacted, its thickness is 30 cm;
• formwork is installed, if the soil is fragile, if it is clayey, then the formwork is installed only for the base - the surface part;
• a reinforcing frame is laid inside, placed on bricks so that it is inside the concrete structure and not lying on a cushion;
• Concrete is poured with vibration;
• after a week the formwork is dismantled, but the foundation can be loaded only after 28 days;
• Usually during this time it is waterproofed by covering the open surfaces with bitumen mastic, and the open areas between it and the walls of the trenches are filled.

Online foundation calculator

To find out the approximate cost of a strip foundation, use the following calculator:

Moisture protection

For a good log bathhouse, it is important to properly waterproof the foundation. The safety of the structure depends on this procedure. It is important to additionally insulate the floor, because in a bathhouse the main part of the heat can escape through the pouring floors.

For strip foundations, roofing felt is most often used. It is laid on the base, glued with hot bitumen lubricant.

The blind area is important for a bathhouse. If you neglect to install it, the wastewater will wash away the soil and the bathhouse will become distorted.

Logs with a diameter larger than the wall material are used as the first crown. The first crown is carefully secured and insulated.

Foundation materials

Practice shows that when the question of how to make a foundation for a bathhouse with your own hands is raised, private developers give preference to monolithic structures, regardless of shape. Rarely does anyone undertake the construction of prefabricated structures. This still requires special skill, especially if a stone is used as a basis. Although there is a fairly simple technology.

Foundation for a bathhouse made of stone Source kamine-store.ru

For example, how to properly make a strip foundation for a stone bath:

• a trench is dug around the perimeter of the building;
• large stones are thrown into it in one layer;
• concrete mortar is poured to fill the space between the stone elements;
• a layer of medium-sized stones is created;
• another portion of concrete;
• and so on to the surface of the soil;
• the formwork of the above-ground part of the foundation is installed;
• and everything is repeated with the middle stones;
• craftsmen even lay out the ground part by hand without formwork, precisely maintaining the dimensions of the structure;
• the most important thing is that there is no reinforcing frame, which increases the cost of the foundation structure.

In fact, the foundation is built from so-called rubble concrete. Stone is a durable material that is not susceptible to strong influences of water and moisture, so such a foundation will last a long time. The only thing you need to know is that it is better to use a stone with sharp edges, uneven planes, depressions, tubercles and other irregularities. Therefore, large river pebbles will not work here. And one more thing - masonry concrete mortar of a grade not lower than M200 will help increase strength.

Features of the steam room and base operation

A home bathhouse is a special type of structure, the operation of which involves the consumption of large amounts of water. This mainly concerns the steam and washing departments. The bathhouse also experiences sudden changes in temperature conditions. All this affects the special requirements for the supporting base of a home sauna.

Intermittent heating

The source of heat in modern baths are boilers, which can be electric, running on solid or liquid fuel.
The soap compartment and steam room are heated for the duration of people's visits. The rest of the time the structure remains cold.

That is, periodically the temperature inside the sauna makes significant fluctuations.

Attention. Sudden changes in temperature, as well as increased levels of humidity inside the bathhouse, can adversely affect the condition of the foundation. Therefore, it is important to carry out hydro- and thermal insulation of the base floor of the building.

Availability of a washing station

A bathing session involves copious amounts of water in the washing area. Waste water in the form of wastewater is removed through a special drainage system, for which a drain is installed in the foundation. If drainage is not done, then moisture over time can destroy not only the structure, but also the foundation itself.

Considering the size of the building

It is not at all necessary to create an individual bathhouse project. There is a large amount of ready-made design documentation for almost all baths that are optimal in size. All that remains is to select the type of foundation and tie it to the local soil conditions. The results of numerous analyzes of the dependence of the choice of foundation on the size of the bathhouse can be reflected in the following table.

Table of the dependence of the choice of foundation on the size of the bathhouse.

Monolithic base.

This is a floating base, poured with concrete over the entire area of ​​the building, a good option for rectangular structures on heavy soils of heaving, weak-bearing or bulk nature. This is a reliable and durable foundation, the thickness of which should be from 30 cm.

A trench 60 cm deep is dug for it and filled with crushed stone and sand, which are repeatedly watered with plenty of water to allow them to shrink. After installing the waterproofing, reinforcement and formwork are done to strengthen the base.

What is the best foundation for a bathhouse?

After pouring concrete, the monolithic foundation is held under wet sawdust or burlap.

Installation of formwork

To create formwork with your own hands, edged boards with a thickness of 25-40 mm are used.

There are other materials, but wood is more accessible, cheaper and easier to work with. In addition, after completion of the work, the boards can be used for other purposes.

The thickness of the boards directly depends on the height of the tape.

The formwork is assembled in stages:

• Assembly of shields. The height is 5-10 cm greater than the height of the tape; the length of the boards is determined by the length of the walls or the size of the boards.
• Installation of shields in the trench. They are fastened together by support strips that determine the thickness of the future tape. On the outside, the shields are reinforced with supports that prevent the mass of concrete from pushing the walls of the formwork outward.
• If the boards are low (up to 20 cm), supports can be omitted, securing the walls from the outside with pegs.

NOTE! When assembling the boards, gaps between the boards should not be larger than 3 mm (ideally, there should be no gaps at all). If gaps appear, they are filled with tow or slats. The installed formwork is a structure whose internal space is the exact shape of a concrete strip

After assembly, all dimensions should be checked to eliminate the possibility of errors.

The installed formwork is a structure whose interior is the exact shape of a concrete strip. After assembly, all dimensions should be checked to eliminate the possibility of errors.

Nothing can be corrected subsequently, so the assembly process must be monitored with the utmost care.

Small ruined subtype.

In turn, it is classified according to the type of structure under which it is erected: self-supporting and load-bearing walls, columns. Can be combined with foundation beams. Solid slabs in the form of ribbed or flat type and massive under the entire structure are becoming popular.

This subtype is widened at the bottom or built in steps. The upper part of the base is the edge that separates the base from the structure itself. The lower part is the sole resting on the base soil.

To learn the procedure for laying a shallow strip foundation, watch the video:

Its height is the distance from the sole to the planning mark of the earth's surface. Sometimes a glass is placed in the upper part under the column.