Do-it-yourself concrete floor filling in the garage: preparing the base, step-by-step instructions

The foundation of any well-designed garage is often a sturdy, well-finished floor. If this is a project you’re taking on on your own, you may be experiencing a mixture of excitement and anxiety. The good news is that, with the right approach and care, filling a garage’s concrete floor can be a do-it-yourself project. By following the proper procedures and doing some advance planning, you can create a long-lasting, flawless surface that will serve you well for many years.

Preparing the base is the first step in making sure the new floor adheres correctly and can withstand wear and tear. This include removing any debris, fixing any damage, and leveling the surface to the greatest extent that is feasible. In addition, you’ll need to determine whether to reinforce the garage floor or add a moisture barrier based on your unique requirements.

After the base is prepared, you will proceed with the actual filling. This include preparing the concrete, mixing it, pouring it, and finishing the surface with tools. Although it may seem simple, each step needs to be done with great attention to detail in order to prevent common mistakes like uneven spots or air bubbles. You will be able to construct a stable, level floor that looks fantastic and functions well if you have a clear plan and are patient.

Therefore, prepare to transform your garage floor by rolling up your sleeves. You’ll have no trouble succeeding with your DIY concrete project if you adhere to these comprehensive instructions. This project raises the value of your house in addition to improving the garage’s functionality.

Device requirements

You should familiarize yourself with the specifications for a concrete floor device before beginning to build a garage:

1. First of all, it must be durable and reliable, withstand the weight of not only a car, but also a heavy van. In addition to vehicles, racks are installed in the garage, tools and spare parts are stored. Therefore, the concrete screed is made durable. Its thickness should not be less than 20 mm.
2. In case of mechanical damage, the floor should not collapse, crumble, or deform.
3. Solvents, fuel and lubricant mixtures, and paints, which are fire hazardous, are often stored in the garage. When they get on the surface, they damage the material and can ignite, so the concrete screed must be resistant to chemical influences and be fireproof.
4. When there is frost outside, it is difficult to maintain the temperature at one level inside the building even with a heating system. Therefore, the garage foundation must withstand significant temperature changes.

Which brand of concrete is better to choose

Concrete can be bought already made or made by hand with a concrete mixer. If you choose to do it yourself, the SNiP table is used to determine the concrete grade:

Concrete grade	Type of coating	Coating thickness, in mm	Hardening time
M200-M350	Reinforced screed	50-70	Days
	Fiber concrete	40
M400-M500	Hardened sand concrete	40	8 days
M500-M550	Hardened concrete	40	8 days

Experts advise creating a reinforced screed with a thickness of 7 cm for passenger cars. There is no allowance for a shock-absorbing pad in the computation.

Preparing the base

The ground is used as a base for pouring concrete mortar, but a sand and crushed stone pad is needed because this kind of base is unstable. It is necessary to remove the upper fertile soil layer to create clean soil before laying the cushion because it contains a lot of microorganisms and organic matter. This will reduce the amount of soil sinking. It’s going to be a shallow pit.

Zero level mark

The floor’s zero level mark must be set before you can calculate the pit’s depth. The floor may be at the same level as the gate or beneath its threshold. A drain is included in the foundation if installation is done below the threshold level. If not, the garage will flood when spring floods occur. Work process:

• the zero level mark is made along the perimeter of the walls using a level or laser level;
• lines are drawn along the beam set at the required height.

After moving the mark along each wall multiple times, a straight line connects the points. Working with this device is not as convenient as using a laser.

Calculation of the thickness of the PGS layers

The thickness of the cushion layer made of gravel and sand must be precisely calculated in order to achieve the required height. To create a light-transport floor, use the following measurements: The ideal thickness for concrete is 10 cm, sand is 50 mm, and crushed stone is 10 cm.

In light of these computations:

1. The depth of the pit should be 25 cm or more. A few centimeters are added to these dimensions if an additional coating is to be laid on the concrete floor.
2. When treating the surface layer with impregnation or paint, adding centimeters is not required.
3. Based on the figures obtained, purchase the exact volume of sand and crushed stone.
4. The thickness of the backfilled layer is controlled using marks applied to the walls. If the width of the building exceeds 2 m, additional stakes are placed in the center, on which marks are made. All marks are leveled.

If the pit is part of the garage project, a pit is dug at this point in the laying process. Concrete is poured into the pit’s bottom to form a floor. After the solution has dried and the sand and gravel cushion has been filled in the garage, bricks are laid out to form the walls of the pit.

Materials for backfill

It is advised by experts to use 30% fine-sized crushed stone and 70% medium-sized crushed stone in a concrete garage to guarantee a high-quality floor. Because gravel has rounded edges, it cannot be used. This makes the base unstable and increases the risk of the screed cracking. There must be no clay impurities in the sand. It is backfilled after being sieved.

Making a cushion under the concrete floor

Carefully leveling the pit’s bottom is necessary before adding the cushion. There shouldn’t be any bumps or depressions. Using a vibrating plate or hand rammer, the soil is compacted.

1. First, a layer of crushed stone is poured, which is also tamped. It will not be possible to properly tamp a 10 cm layer of crushed stone, so it is poured in parts of 4-5 cm.
2. The first part is evenly distributed over the entire area, then tamped. In this case, half of the material will enter the soil, compacting it. Thanks to this, the likelihood of subsidence is eliminated, the bearing capacity of the structure increases.
3. The rest of the rubble is filled in the same way. If there are no human traces left on the surface, then the compaction has been done well.
4. Sand is poured on top of the rubble, also divided into several parts. It is moistened before compaction.

Then they start driving the pit’s walls away. The finished floor is raised or brought level with the walls. This way, you won’t have to worry about the pit filling with water when you wash your car inside the garage.

Damper gap

The floor and walls can occasionally rise or fall. A damper tape is positioned between the concrete and the wall to keep the screed from cracking at this point and to preserve its integrity. This allows for the creation of a gap during installation, preventing the entire structure from being pulled down with the walls as they shrink. This earned a concrete floor on the ground the nickname "floating" as a result. Use thin foam plastic (10 mm thick) in place of tape after cutting the sheets into strips that are 15 cm wide. The tape is cut off if any portion of it peeks above the finishing.

Waterproofing a concrete floor in a garage

While high humidity does not damage concrete, it can cause corrosion in cars and other items kept in garages. The selection of waterproofing material is contingent upon the groundwater level.

1. In order for concrete to retain its strength and not crumble, it requires moisture. If groundwater is deep, moisture from concrete is absorbed into the sand. To prevent this from happening, a polyethylene film with a density of more than 250 microns is laid on top of the sand.
2. If groundwater is high, the garage may be flooded during spring floods. Therefore, it is necessary to use a denser film. Gidroizol or any other analogue will do. To reduce water penetration inside to a minimum, the film sheets are laid with an overlap, and the joints are sealed with double-sided tape. The material is brought out along the wall, temporarily fixed above the damper tape. The excess part is cut off after the concrete has completely hardened.

Reinforcement

Given that it is frequently subjected to large loads, the concrete floor needs to be reinforced. A ready-made mesh with a cell size of 15 cm and a wire diameter of 7-8 mm is required for installation.

1. The mesh is laid in pieces overlapping each other with a distance of 1 cell.
2. The pieces are tied with wire or plastic clamps. This results in a single reinforcing system.
3. The mesh cannot be laid directly on the film, it must be located in the middle of the concrete. If the depth of the location is less than 3 cm, the mesh may be subject to corrosion.
4. Using bricks or special supports, it is raised 4-6 cm above the waterproofing layer. This arrangement will prevent cracking of the screed, extending its service life.

Installation of beacons

Leveling the concrete screed involves using beacons and a building rule. You can buy beacons in stores or make your own with pipes and bars. Rules for installation:

1. Beacons are placed parallel to the marks made on the walls for the concrete slab.
2. Mix a thick solution, from which slides are laid out. Beacons are pressed into them. Work begins along the wall opposite the doors, gradually moving towards the exit.
3. The distance between the beacons should be less than 25 cm (the length of the rule). The first beacon is installed at a distance of 30 cm from the wall.

The concrete surface should slope slightly so that water from the floor naturally runs down to the street. 24 hours after pouring, beacons are taken down. The resulting voids are leveled with the floor and filled with a concrete mixture.

To achieve a smooth and durable finish on a do-it-yourself concrete floor filling project in your garage, proper base preparation is essential. This guide will take you through all the necessary steps, from leveling and cleaning the old floor to mixing and pouring concrete, and it will provide you with helpful advice to make the process go more smoothly and produce results that look professional. Regardless of your level of experience, this methodical approach will enable you to confidently and successfully complete the task at hand.

Pouring a concrete floor in a garage

A lot of mixture will be required to concrete the garage floor due to the slab’s large thickness and slope. Frost-resistant qualities and relatively strong characteristics characterize concrete grade M250.

1. For a garage measuring 4 × 6 m, you will need about 3 m³ of solution.
2. Sand and cement (in proportions 1:3 or 1:4) are loaded into a concrete mixer, water is added and mixed thoroughly. The finished mixture hardens in 2 hours, so concreting is carried out quickly.
3. The base is filled with the mixture, and excess air is removed using a deep vibrator. It is lowered at different points of the screed until laitance appears on the surface.
4. Then level with a long wooden strip.
5. If pits or other imperfections occur, additional filling of the solution is required. Then the surface is leveled again.

All of the work is completed in a single approach to create a monolithic base.

Insulated concrete floor in garage

There are two methods for insulating a garage’s concrete floor: either place the insulation beneath the slab or cover it with screed on top. Below the slab, installation is completed as follows:

1. Extruded polystyrene can withstand heavy loads, has good vapor and waterproofing properties, so it is chosen for work. The density of the material should not be less than 35 kg/m³.
2. It is laid on a waterproofing layer, a reinforcing mesh is mounted on top. You can lay a layer of geotextile under the mesh. It evenly distributes the load over the entire surface and does not allow the insulation to be pressed through.
3. To more reliably isolate the floor from the ground, installation is carried out with offset seams. The material is folded in 2 layers. The minimum thickness should be 5 cm.

Concrete is poured after it is laid.

Step	Description
1. Clear the Area	Remove any old flooring, debris, and dust from the garage floor.
2. Fix Cracks	Fill any cracks or holes in the existing floor with concrete patching compound.
3. Level the Surface	Ensure the floor is level. Use a self-leveling compound if needed.
4. Install a Moisture Barrier	Lay a moisture barrier sheet to prevent water from seeping up through the concrete.
5. Build Formwork	Set up wooden forms around the edges of the area to hold the new concrete in place.
6. Mix Concrete	Prepare the concrete mix according to the instructions on the bag.
7. Pour Concrete	Pour the concrete into the forms, spreading it evenly with a shovel or rake.
8. Smooth the Surface	Use a trowel to smooth the surface and remove any air bubbles.
9. Let It Cure	Allow the concrete to cure for at least 24-48 hours before walking on it.
10. Remove Formwork	Once the concrete is fully set, remove the wooden forms carefully.

Although filling a concrete garage floor can appear like a difficult undertaking, it’s a task you can complete on your own with the appropriate planning and strategy. Your garage floor can be transformed into a smooth, long-lasting surface by following the instructions provided. An effective do-it-yourself concrete floor requires careful planning and execution.

Make sure the base is ready to go first. This entails clearing the space, resolving any problems, and using an appropriate base material. It will be worthwhile to take the time to do this correctly in the end. A properly prepared base minimizes future issues and improves concrete adhesion.

After preparing the base, mix and pour the concrete in accordance with the directions. Be sure to spread the concrete evenly and with efficiency. The process will go more smoothly and result in a better finish if you use the proper equipment, such as a trowel and screed.

Remember to properly cure the concrete after pouring. In order to achieve the strength and durability of your new floor, this step is essential. Maintaining a damp and covered surface will aid in proper setting and help shield it from cracking.

You don’t need to hire a contractor to accomplish a professional-looking finish if you have patience and pay attention to detail. Savor the satisfaction of finishing the project yourself and your new garage floor. It’s a fantastic way to increase the value of your house and improve the usability of your garage.

Video on the topic

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