The appearance of water in the caisson of the garage is not just a nuisance, but a direct threat to the safety of the car and the structure itself. When the groundwater level rises, the steel or concrete structure begins to experience tremendous pressure, and corrosion destroys the metal at an alarming rate. Owners often face a dilemma: Trying to pump water out indefinitely or radically solve the problem by filling the space around and inside the structure.
The choice of material for filling depends on many factors: the type of soil, the material of the caisson itself, the depth of the waters and financial capabilities. Incorrectly selected filler can lead to surfacing of the container, deformation of the walls or displacement of the foundation of the garage. In this article, we will discuss in detail, kaissonTo ensure durability and dryness in the room.
There are several time-tested methods, from the use of classic ceramsite to modern foam concrete. Each of them has its advantages and disadvantages that must be considered before starting work. Ignoring the technology of preparation can negate all efforts, so it is important to understand the physical processes occurring in the ground.
Diagnostics of the problem and preparation for work
Before purchasing materials, it is necessary to conduct a thorough diagnosis of the condition of the caisson. Water can come in through seams, cracks in metal or simply rise from below if the structure is not sealed. If you plan to fall asleep caisson completely, it is important to make sure that its walls will withstand the pressure of the soil in the event of possible drainage in the future, or to accept the fact that the design will become disposable.
The first step is always to pump water. You can use submersible pumps designed to work with dirty liquid. After removing the main mass of water, it is necessary to give time to the residues drain from the walls and bottom to assess the actual amount of incoming moisture. Drainage pumps The float mechanism will be most effective here.
⚠️ Before starting any work inside the caisson, make sure there are no gasoline vapors or exhaust gases that are heavier than air and can accumulate in the lower part. Airing is required!
If the water arrives too quickly and it is impossible to pump it out without powerful industrial equipment, the option is with concrete under water, but this is another technology. For standard backfilling, a relatively dry or minimally wet base is required. It is also important to clean the bottom of silt and debris, as organic matter will eventually rot, forming voids.
Inspect the exterior walls if you have access to them from the outside (for example, when building a new garage). The presence of waterproofing outside is a key factor in longevity. If the caisson is already installed and sprinkled, you will have to work from the inside, which complicates the process of sealing the seams and corners.
Requirements for filling materials
The material used to fill the caisson or the space around it must have characteristics. The main one is low hygroscopicity. If the backfill absorbs water, it will turn into a heavy mass that can push the bottom or create excessive lateral pressure. In addition, wet material loses its thermal insulation properties.
The second important parameter is weight. Lightweight fillers are preferred as they do not require reinforcement of the garage foundation. Heavy mixtures such as pure concrete or clay may require additional calculations of the load-bearing capacity of the soil under the foundation. Material density It directly affects the complexity of delivery and installation.
The third aspect is chemical inertia. In the garage environment, spills of fuel, acids from batteries or other aggressive liquids are possible. The material must not react with these substances, break down or release toxic fumes. Fire safety is also important, especially if the caisson is under the observation pit or in close proximity to the electrical wiring.
Different mixtures are suitable for different purposes. If you just need to remove the void so that the water does not splash, only solutions will be suitable. If the goal is to create a warm cushion and dry space, the choice is narrowed to more expensive, but effective options. ceramsite concrete It often becomes a compromise between cost and functionality.
Let’s look at the main types of materials available in the modern construction market. Each of them has its own niche application and technological features of laying. An error in the choice can lead to the fact that in a couple of years you will have to open the floor and redo the work.
Overview of materials: from sand to polystyrene foam
The most accessible and common material is sand. However, you need to use only coarse-grained, washed sand, preferably river sand. It does not hold water and does not ooze when frozen. But sand has a significant disadvantage - high thermal conductivity. Caisson covered with sand will be cold and condensate can form on walls.
Ceramzite is an excellent thermal insulator that is much lighter than sand. Ceramsite granules do not absorb moisture inside themselves, if they are of high quality. However, when fully immersed in water, ceramzite can gain weight, so it is often used in a mixture with cement mortar. ceramsite concrete It combines the strength of the stone and the lightness of the porous aggregate.
Styrofoam (foam) and extruded polystyrene (foam)XPS) - leaders in thermal insulation. They are not afraid of water and have a minimum weight. Filling with a tiny foam or laying sheets is ideal for keeping warm, but this material is fuel and requires protection from rodents who like to nest in it.
Ground mixtures with the addition of lime or clay were used in the old days, but today their use is limited. Clay creates a "castle", but when wet it becomes heavy and slippery, and when drying it cracks. The use of clean soil is not recommended due to the risk of swelling and instability of volume.
To create a monolithic structure, concrete mixtures with light aggregates are often used. This turns the caisson into a massive block that is guaranteed not to pop up. However, this option deprives access to internal communications, if they are laid inside the walls of the caisson.
Technology of filling the caisson with their own hands
The process of filling the caisson requires consistent execution of operations. A disruption of technology can lead to the formation of voids that will eventually fail, creating a hole in the garage floor. First, you need to prepare the surface: clean rust, treat with anticortisol and, if necessary, apply waterproofing.
☑️ Preparation for caisson filling
If a bulk material (sand, ceramzite) is used, it must be covered with layers. Each layer with a thickness of 20-30 cm must be carefully tamped. For this, you can use a vibroplate (if access allows) or manual tramping. Water pouring helps the sand settle, but with ceramsite, this method should be used carefully so as not to damage the granules.
When working with concrete solutions, it is important to observe proportions. The mixture should not be too liquid, otherwise the water from it will go into the ground or absorb into the dry walls, leaving a loose structure. Adding plasticizers improves fluidity without excess water. Reinforcement The upper layer of concrete screed with a metal mesh will increase the strength of the floor.
⚠️ Attention: When filling with light materials (foam, ceramzite), be sure to leave the ventilation ducts if the caisson is not filled completely, otherwise condensation may form inside.
If the caisson is metal, the backfill pressure should be uniform on different sides so as not to deform the walls. Therefore, the backfill is carried out layer by layer, raising the level simultaneously along the entire perimeter. A sharp pressure on one side can dent the metal.
The final stage is the finishing device. Usually it is a concrete screed with a thickness of at least 10 cm, reinforced with a mesh. It distributes the load from the car and protects the insulation or backfill from mechanical damage.
Waterproofing and corrosion protection
Even if you decide to fall asleep, the question of waterproofing remains relevant, especially for metal structures. The water in the soil contains salts and chemical elements that accelerate electrochemical corrosion. Without protection, the metal will rust in a few years.
The most effective external waterproofing, but in the already built garage is available only internal. Bitumen mastics, liquid rubber or penetrating compounds are used. Bitumen-polymer mastics create an elastic film that does not crack when the ground moves.
For metal caissons, cathode protection is an excellent solution, but it requires a source of current. A simpler method is the use of corrosion inhibitors in the primer. It is important to qualitatively process welded seams, since this is where rusting begins in the first place.
| Materials | Thermal conductivity | Moisture resistance | Weight. | Price. |
|---|---|---|---|---|
| Sand | Tall. | Tall. | Heavy. | Low. |
| ceramzit | Low. | Medium | Lightweight | Medium |
| polystyrene | Very low. | Tall. | Very light. | Tall. |
| concrete | Tall. | Medium | Very heavy. | Medium |
If the caisson is concrete, waterproofing is also necessary, since the concrete has a capillary structure and can let moisture through. Penetrating waterproofing clogs the pores of concrete, making it waterproof. This is especially important if you plan to store food or equipment inside.
Common errors in filling
One of the most common mistakes is saving on preparation. An attempt to fill up the caisson, in which there is water or a layer of silt, will lead to the fact that the organics rot, and the floor will fail. Quality preparation of the bottom is the key to success.
The second mistake is the use of construction waste. Broken bricks, wooden pruning and other debris eventually collapse, absorb moisture and create foci of corrosion. Caisson is not a garbage can, you need to fill it with special materials.
The clay castle myth
Many people believe that clay is the perfect waterproofing. In practice, clay works only in dry soils. With constant contact with water, it blurs, and when drying it cracks, losing its tightness.
Ignoring ventilation is another problem. Even in a covered caisson, air must circulate to remove moisture that is inevitably formed due to temperature differences. Absence breather or ventilation pipes will cause dampness in the garage.
Communications protection is often overlooked. If pipes or cables pass through the caisson, they must be protected with shells. Soil pressure and possible movements can overwhelm unprotected communications, and access to them after filling will be impossible.
Use geotextiles to separate layers of backfill (for example, between sand and rubble). This will prevent the materials from mixing and siltation of drainage.
FAQ: Frequently Asked Questions
Can you fill the caisson with ordinary earth from the pit?
It's not recommended. Ordinary earth contains organic matter that bends over, forming voids. In addition, the clay in the composition of the earth when wet expands (burrows), which can deform or destroy the walls of the caisson. Use inert materials: sand, PGS or ceramzite.
Do I need to re-reinforce the floor after filling the caisson?
Yes, reinforcement is mandatory if you are planning to drive a car or install heavy equipment. The layer of concrete on top of the backfill works as a flooring plate, and the reinforcement mesh (cell 100x100 or 150x150 mm) will prevent cracking under loads.
What if water arrives faster than it is pumped out?
In this case, filling is impossible without a preliminary drainage device around the garage or caisson. We need to lower the groundwater level. If this is not possible, the caisson is filled with concrete with hydrophobizers, turning it into a monolithic block, but it is expensive and time-consuming.
What is the thickness of the sand layer that is sufficient?
If the caisson falls asleep completely, then to the floor level. If only a cushion is made, the minimum thickness of the sand layer to cut off capillary moisture is 20-30 cm. For thermal insulation, the layer of ceramzite should be at least 15-20 cm.
Properly selected material and compliance with the backfill technology will turn a problematic caisson into a reliable base for the garage floor, forever eliminating dampness and corrosion.