Construction of a garage does not begin with the construction of walls, but with the creation of a reliable foundation that will carry the load of the entire structure. The foundation of the blocks It is one of the most popular solutions for lightweight buildings, as it combines the speed of installation and the affordable cost of materials. Unlike monolithic tape, the block base requires less time to dry and allows you to start laying walls almost immediately.
The choice of block technology is often due to the ability to carry out work in a short time without the involvement of heavy machinery. However, despite the apparent simplicity, this process requires accurate calculation and compliance with the technology of soil preparation. Errors at this stage can lead to skewed walls, cracks in the structure and violation of the tightness of the room.
In this article, we will discuss in detail all the stages of creating a base from concrete blocks, starting from the choice of material and ending with waterproofing. You will learn how to properly prepare the pit, what solution to use for masonry and what nuances to take into account when working on different types of soils. Competent approach foundational It guarantees the longevity of your garage.
Advantages and Disadvantages of Block Foundation
The main advantage of using concrete blocks is the high speed of construction of the structure. FBS blocks (the foundation blocks are solid) or lighter analogs allow the foundation to be assembled in a few days, while monolithic concrete takes time to gain strength. This is especially true when construction time is limited by weather conditions or work schedules.
In addition, the block foundation has a high load-bearing capacity if it is properly designed. Concrete products of factory production have a clear geometry and the declared brand of strength, which simplifies the calculation of the load. Modularity The design makes it easy to change the configuration of the foundation or to increase it in the future, if there is a need to expand the garage.
However, there are also shortcomings that need to be taken into account. Chief among them is the presence of seams between the blocks, which are bridges of cold and potential ways of moisture penetration. No quality. waterproofing And insulation such a foundation can freeze, which will lead to dampness in the garage. Also, for the installation of heavy blocks, it may be necessary to rent a crane, which increases the estimate.
⚠️ Note: The use of blocks with internal voids (IV) for the foundation is possible only on rocky soils. For pulpy soils, only full-body products are suitable.
Selection of materials and calculation of quantity
For the construction of a garage, solid foundation blocks (FBS) are most often used, which are made of heavy concrete. They are marked with numbers indicating length, width and height in decimeters. For example, block FBS 24-4-6 It has a length of 2380 mm, a width of 400 mm and a height of 580 mm. The choice of a specific size depends on the thickness of the walls of the future garage and the type of soil.
In addition to FBS, for lightweight structures (for example, metal or wooden garages) can be used ceramzytoconcrete or foam concrete blocks. They are lighter and have better thermal insulation properties, but their load-bearing capacity is lower. Calculation of quantity The material is made on the basis of the perimeter of the future structure and the height of the cap.
Do not forget about consumables, such as cement mortar and fittings. For laying blocks, a solution of a brand not lower than M100 is used, which provides a strong adhesion of the elements. Also required material to create cushions (sand and rubble) and waterproofing roll materials.
| Type of block | Dimensions (mm) | Weight (kg) | Application |
|---|---|---|---|
| FBS 24-4-6 | 2380×400×580 | 1300 | Building walls, heavy soils |
| FBS 12-4-6 | 1180×400×580 | 640 | Extensive elements, light construction |
| FBS 9-4-6 | 880×400×580 | 350 | Hand-mounting without a crane |
| PB (hollow) | 200×200×400 | 15-25 | Only for dry soils |
How to save money on the delivery of blocks?
When ordering blocks, try to choose the number so that they completely fill the truck body. Delivery of incomplete machine (underload) is often charged at a full tariff, which increases the cost of a unit of material. It is also advantageous to order material from manufacturers closer to the construction site, as the weight of the blocks makes logistics a significant part of the budget.
Preparation of the site and marking of the pit
The first stage of work is a thorough preparation of the construction site. It is necessary to remove the upper fertile layer of soil, since it contains organic matter, which will eventually rot and cause the foundation to draw down. The depth of soil removal is usually 20-30 cm. After that, the plot is planned and the excess land is removed.
Foundation marking is a critical process that requires high accuracy. For this purpose, pegs and construction cord are used. We drive stakes in the corners of the future garage and stretch the thread, forming an external contour. It is important to check the diagonals of the resulting rectangle: they should be perfectly equal. The permissible error is not more than 2 cm.
If the soil on the site is weak or the level of groundwater is high, it may be necessary to dig a pit over the entire area or a larger-width trench for ease of installation. The bottom of the trench should be leveled along the horizon using a level or laser level. Depth of laying It depends on the freezing of the soil in your region and the weight of the structure.
- 🏗️ Remove the fertile soil layer throughout the building area.
- 📏 Mark the axes of the walls with stakes and cords, checking the diagonals.
- 💧 Keep water drainage if work is done during the rainy season.
- 🚜 Line the bottom of the trench and tamp it with a manual tamper.
It is important to consider that the width of the trench should be 20-30 cm wider than the blocks themselves to ensure the possibility of installation of waterproofing and drainage devices. If you plan to make an observation pit in the garage, its contours are also marked at this stage.
Sand cushion device and bases
The blocks cannot be laid directly on the ground, even if it seems very dense. It is necessary to create a shock-absorbing and leveling pillow. To do this, the bottom of the trench is filled with a layer of sand 10-15 cm thick. The sand is shed with water and thoroughly trampled to the state when the footprints cease to remain on the surface.
A layer of crushed fraction 20-40 mm thick about 10 cm is laid on the sand. The gravel is also trampled. Such a two-layer cushion (sand + gravel) prevents capillary moisture from the ground and evenly distributes the load from the weight of the garage to the base. On top of the rubble, it is recommended to lay a layer of skinny concrete (battery) 5-10 cm thick or a layer of waterproofing so that the cement milk from the solution seam does not go into the ground.
☑️ Preparation of the basis
If you use FBS blocks, then the first layer is often laid with special tile blocks (FL) or poured with monolithic reinforced concrete tape. This allows you to increase the area of support and level the differences in height. Monolithic tape is reinforced with a grid or frame of reinforcement with a diameter of 10-12 mm.
⚠️ Warning: Never skimp on the pillow. Insufficiently compacted base will lead to uneven shrinkage of blocks and cracks in the walls of the garage in the first year of operation.
Blocklaying technology and reinforcement
Installation of blocks begins with the installation of corner elements. These are the most important points on which the geometry of the entire foundation depends. The corner blocks are placed with special care, their horizontality and position relative to the axes are checked. Between the installed corners stretched berth cord, which serves as a guide for laying intermediate blocks.
The solution for masonry is prepared from cement and sand in a ratio of 1: 3 or 1: 4. The consistency should be plastic, but not too liquid. The solution is applied to the lower surface of the installed block and on the ends of the already laid adjacent blocks. The thickness of vertical seams should be 10-15 mm, horizontal - about 20 mm. All the joints should be completely filled with solution.
To increase the strength of the structure, especially on unstable soils, a reinforcement mesh or rods are laid between the rows of blocks. Reinforcement is done every 2-3 rows of masonry. Also, the reinforcement belt is mandatory in the uppermost row, on which the walls of the garage will rest. This creates a single rigid frame.
When installing it is important to observe the ligation of the seams. Vertical seams in adjacent rows should not coincide. The blocks are installed with displacement, like brickwork, which ensures the monolithic structure. If the whole blocks are not part of the side size, additional elements are used or brickwork is laid out in the intervals.
When laying the first row of blocks, use more solution to level out possible cushion irregularities. First row horizontally check with laser level after installation of each unit.
Waterproofing and base insulation
Concrete is a porous material that is able to absorb moisture from the ground. For the garage, this is critical, as dampness will lead to corrosion of the car and damage to stored property. Therefore, waterproofing the foundation from the blocks is a mandatory stage. The most effective coating waterproofing with bitumen mastics in combination with pasting materials (ruberoid, glassizole).
First, the surface of the blocks is cleaned from the influx of solution and dust, then it is ground by the primer. After drying the primer is applied a layer of bitumen mastic. A roll waterproofing device is pasted over the mastic. It is important to cover the canvases at least 10 cm and carefully miss the joints. Horizontal waterproofing is laid between the foundation and the first row of walls.
Insulation of the foundation is necessary if the garage is heated or located in a harsh climate. Extruded polystyrene is most commonly used (EPPS), which does not absorb moisture and is highly durable. The insulation plates are glued to the outside of the foundation on top of waterproofing and are additionally fixed with dowels.
- 🛡️ Apply the bitumen primer on the cleared foundation walls.
- 🔥 Spray the surface with bitumen mastic in two layers.
- 📜 Stick ruberoid or glassizole, warming the joints with a burner.
- ❄️ Stick to the EPPS plates for thermal insulation (optional).
High-quality waterproofing extends the life of the foundation by 2-3 times and protects the garage from dampness, so it is absolutely impossible to save on bitumen materials.
Frequently Asked Questions (FAQ)
Can you build a foundation of blocks with your own hands without a crane?
Yes, this is possible if you use small blocks (for example, 880 mm or 1180 mm long), the weight of which allows two or three workers to lift them manually. You can also use blocks of foam concrete or ceramzitoconcrete, which are much lighter than concrete FBS. However, for standard FBS 24-4-6 units, renting a crane or manipulator is mandatory.
What depth of foundation is needed for a garage of foam blocks?
The depth depends on the level of soil freezing in your area. For light garages, foam blocks often make a shallowly buried foundation (40-60 cm), but it must necessarily rely on a non-bulk base (sand / gravel). If the soils are hollow, the foundation should be buried below the freezing point, otherwise the forces of frost bloating can lift the building.
Do I need to reinforce each block?
No need to reinforce each row. Usually, the rebar belt is arranged at the bottom (at the level of the sole), every 3-4 rows of masonry and necessarily in the upper row under the walls. This is enough to create a rigid structure that is resistant to deformations.
What is better to fill the sinuses of the foundation after installation?
It is best to use sand or a sand-gravel mixture. These materials do not retain water and are not exposed to frosty bloating to the same extent as clay. Backfilling should be made layer by layer with tramping to avoid voids in which water can accumulate.
How long do you have to wait before the walls start?
Unlike monolithic concrete, the foundation of blocks does not require time to gain strength, since the blocks have already gained their factory strength. You can start the construction of walls immediately after the solidification of the masonry mortar on which the blocks were installed (usually 2-3 days), and the completion of waterproofing work.