Miscalculating the depth of the foundation for the garage often leads to cracks in the walls or skewed gates in the first winter. If you plug the sole above the level of freezing on thick soils, the forces of frost bloating will push the structure, violating the integrity carrier. That is why determining the exact figure to dig the trench is the primary task before starting work.
There is a direct relationship between the weight of the future structure and the type of soil. Light garage of flooring and foam blocks does not require a massive tape-baseA two-story building with a workshop will require a serious approach. Ignoring the geological features of the site can lead to the fact that concrete-ribbon It will burst under uneven ground pressure.
In this article, we will discuss the specific depth values for different soil types and climatic zones. You will learn how to independently conduct an express analysis of the soil and choose between a shallow and full-fledged foundation. Rightly chosen freeze-deepness It will guarantee the durability of your building.
⚠️ Warning: Construction on peatlands or silts without prior soil replacement or the use of piles is strictly prohibited, since the carrying capacity of such soils is critically low.
Factors affecting depth of storageDetermining how deep a trench is to dig is based on a complex of technical and natural factors. The main parameter here is ground-freezing depth (GPG) in your region. If the sole of the foundation is above this mark, the water in the soil, turning into ice, will begin to expand and press on the walls of the structure from below and from the sides.
The second critical aspect is the level of groundwater. High aquifer may require a drainage device or the choice of another type of base, for example, a monolithic plate. In such conditions, digging deep can be not only expensive, but also technically difficult due to the constant influx of water.
The third factor is the load from the building itself. A heavy brick garage with concrete overlap will create much more pressure on the ground than a lightweight frame structure. Heavy structures often require leaning on dense layers of soil below. freeze-line.
For an accurate determination of the groundwater level, drill a well with a diameter of 100 mm in the place of the proposed construction and leave it for a day. The water level in the well will show the real horizon of the aquifer.
Analysis of soil type at siteBefore ordering concrete or buying blocks, you need to understand what you will have to work with. The soils are divided into hollow and non-bulky, which directly dictates the requirements for foundation. Fuzzy soils (clays, loams, soups) increase in volume to 10% when frozen, creating enormous pressure.
Non-fluffy soils, such as large sands, gravel and rock, practically do not change their volume at negative temperatures. On such grounds, the depth of the foundation for the garage can be minimal, since the risk of deformation is reduced to zero. However, clean sand is rare, so detailed analysis is often required.
For self-assessment, you can dig a hole with a depth of about 1.5-2 meters. If the samples are dominated by sand and stone, you are in luck. If you are in a position to be in a position of squatting, then you will be in a position to be in a position of squatting. clay-ground, which requires special attention.
Methods for determining soil moisture
Take a lump of soil and try to roll it into a tourniquet with a diameter of 1 cm. If the tourniquet does not work and crumbles, the soil is dry. If the tourniquet is there, but cracks when folded into a ring - the soil is stiff-plastic. If the ring is solid and smooth, the soil is fluid, which is dangerous for construction.
Normative values of the depth of freezingThe depth of freezing is a calculated value that depends on the climatic zone. In different regions of Russia, it varies from 0.5 meters in the south to 2.5 meters in Siberia. Building a foundation without considering this data means risking the integrity of the walls.
There is a formula for the refined calculation, but for the garage most often use tabular values from the SNIP 23-01-99. These data are averaged and take into account the type of soil and the average monthly temperatures of the winter period.
Below is a table with indicative values of the depth of freezing for different cities and soil types:
| City/Region | Clays and loams (see para. | Sands of soupesi (cm) | The sands are large (cm) |
|---|---|---|---|
| Moscow and the region | 120 | 135 | 145 |
| St. Petersburg | 120 | 130 | 140 |
| ekaterinburg | 180 | 200 | 215 |
| Novosibirsk | 200 | 220 | 240 |
| krasnodar | 80 | 90 | 100 |
It is important to understand that these figures are relevant for open areas. If the garage is heated, the ground under it will not freeze, and the depth can be reduced. For unheated garage, it is necessary to comply with the standards or use insulation basement.
For an unheated garage, the foundation depth should be equal to or greater than the standard ground freezing depth in your area.
A Small-Scale Foundation: When PossibleMany developers are looking to save money and choose a shallow-deep ribbon (MZLF). This is only justified if certain conditions are met. First of all, this option is suitable for light buildings on non-lumpy or weakly bulging soils.
The essence of technology is that concrete-ribbon It is laid to a depth of 30-50 cm, but it is necessarily insulated and reinforced. This allows the structure to "swim" along with the movements of the ground without breaking down. However, for heavy brick or block garages, this method can be risky.
If you decide to do MZLF, you need to ensure the removal of water from the perimeter of the building. Presence lantern with a heater with a width of at least 1 meter is a prerequisite. Without this, the heat from the ground will go away, and the soil under the foundation will begin to freeze deeper.
- 🏗️ Suitable for frame and wooden garages.
- 💰 Significant savings on earthworks and concrete.
- ❄️ It requires mandatory insulation of the cap and the window.
Full tape and plate baseWhen it comes to a capital structure with an observation pit or basement, the depth of the foundation for the garage is determined by the project and often exceeds 1 meter. In this case, a full-fledged deep-ropeIt is based on a non-freezing layer of soil.
Such a foundation requires careful waterproofing, as it will be subjected to constant pressure of moist soil. The walls of the tape should be flat, without voids, to exclude lateral friction during soil movements. Often used for such purposes foundation blocks (FBS) Or monolithic concrete.
An alternative to the tape can be a monolithic plate. It is submerged slightly, but due to a large area distributes the load. The stove is ideal for problem soils where digging deep is impossible or too expensive. It's called a floating one. foundationIt will quench any movement of the soil.
⚠️ Note: When installing an observation pit, the depth of the foundation should take into account the height of the pit. Often in such cases, a combined foundation is made or the tape is lowered below the bottom of the pit.
☑️ Checking the filling readiness
Base preparation technologyRegardless of the depth chosen, the preparation of the pillow is a critical stage. At the bottom of the trench pours a layer of sand thickness of 15-20 cm, which is spilled with water and tamped. This creates a shock-absorbing layer that compensates soil-deformation.
A layer of rubble is often laid over the sand, which prevents the capillary rise of moisture to the concrete. The whole structure is closed with waterproofing film before installing the valve. Quality waterproofing Extends the life of the concrete at times.
Reinforcement is carried out in two belts for belt foundations. The upper and lower rows of the valve are connected by vertical racks. The use of composite reinforcement is possible, but the classic metal-rod The diameter of 10-12 mm remains the standard of reliability.
Frequent errors in depth calculationOne of the biggest mistakes is ignoring the terrain. On the slope, the depth of the foundation will be different: on the one hand, it can be shallowly buried, and on the other hand, it can go deep into the ground. This is a necessary approach to calculation resilience.
Communication is often overlooked. If water pipes pass under the garage or near, they also need to be protected from freezing. Sometimes this affects the depth of the digging, as the foundation should not violate the integrity of the engineering networks.
Another mistake is saving on the width of the tape. Depth is not the only parameter. The width of the sole must be sufficient to distribute the weight. For a single-storey garage, 30-40 cm is usually enough, but for a two-storey one, this parameter must be recalculated, taking into account the load-bearing soil.
- 🚫 No drainage at high water levels.
- 🚫 Use of low-quality concrete (below the M200 brand).
- 🚫 Filling the foundation in several stages without the device of seams.
Do you need to build a deeper foundation if the garage is next to the house?
Yes, if the foundations are independent, their soles should be at the same level or the foundation of the garage should be higher, so as not to transfer pressure to the base of the house. If the levels are different, uneven ground rise is possible.
Can I build a garage without a foundation?
Only if it is a temporary lightweight construction of decking or wood. For capital storage of the car and tools, the lack of a foundation will lead to dampness, skewed gates and rapid destruction of the structure.
What kind of concrete to choose for the garage foundation?
The best choice is the concrete brand M200 or M250. For heavy soils or heavy loads it is better to use M300. Use of the brand below M150 for the foundation is not recommended.
Does the presence of a cellar affect the depth of the foundation?
Absolutely. If the cellar is under the garage, the depth of the foundation is determined by the depth of the cellar. The walls of the cellar in this case serve as a foundation, and they should be buried below the freezing level.
How long should the foundation dry before the walls are built?
The set of strength of concrete occurs for 28 days at a temperature of +20 ° C. However, you can start laying the first rows after 7-10 days, when the concrete will gain about 70% of the strength. Complete drying takes longer.