Waterproofing of the floor before the screed

Waterproofing of the floor before the screed is necessary for two reasons: firstly, it prevents the penetration of moisture vapor from the basement or from the lower floor into the concrete screed, and secondly, it protects the floor slab from possible water leakage in wet rooms. It is especially important to perform high-quality waterproofing of the floor before the screed on the first floor of a private house that does not have a basement. Water vapor and capillary moisture rising from the ground often have an acidic or alkaline environment, they actively interact with concrete components, and after a few years the screed can become covered with a network of cracks and begin to break down.

Types of floor waterproofing before the screed

There are several methods of waterproofing the floor before the screed. In private houses without a basement, a gravel-sand cushion is often used as the first layer of waterproofing. First, gravel or crushed stone is poured under the base of the floor, it is compacted and then covered with sand. The resulting cushion, due to the presence of air gaps between the particles, prevents the capillary rise of moisture from the ground. At the same time, it practically does not protect it from water vapor, therefore additional film hydro-isolation is required.

Steam insulation films as a floor waterproofing before the screed are used not only in private houses, but also in urban apartments. The films allow the creation of a waterproof coating and protect the screed from water vapor and moisture from the floor slabs, as well as the slab itself from water leaks in wet rooms.

The third type of waterproofing the floor before the screed is a coating of waterproofing. It is carried out with mastics based on bitumen or rubber, applied in several layers. A distinctive feature of this screed is the ability to fill any uneven surfaces, which is especially convenient with a large number of pipe penetrations.

In addition, to impart waterproofing properties to concrete slabs, they can be treated with a solution of impregnating waterproofing. This technology is relatively new, but it has already gained popularity among builders due to its simplicity and efficiency. Concrete is impregnated with a solution of penetrating waterproofing on the surface from either side of the floor, then in the pores of concrete, when interacting with its components, the growth of needle crystals begins, preventing the penetration of moisture into the concrete.

Technology of gravel-sand cushion

1. Preparation of the base consists in leveling the soil under the future floor and removing a fertile layer containing organic impurities from it. Usually, this is done at the stage of preparation of the site for construction.
2. The prepared soil is filled with crushed stone with a fraction value of not more than 50 mm. Backfill is produced throughout the floor area. Gravel is rammed, leveled to exclude large elevations. The thickness of the layer is not less than 0.2 m, and in areas with a close location of groundwater - at least 0.5 m.
   

   Gravel packing process

3. Fill the gravel with a layer of 0.1-0.4 m sand. Coarse sand is spilled with water and carefullyTamped with a hand roller.
4. Cover the gravel-sand cushion with a layer of geotextile. Strips of geotextile are glued using a construction hair dryer. Geotextile plays the role of shock absorber and protects the insulation and waterproofing from damages.
5. On top of the geotextile butt put a foam insulation, for example, polystyrene or penokleks. Polyfoam is not recommended because of its low mechanical strength.
6. After performing these operations, it is possible to perform waterproofing of the prepared substrate with roll materials or to immediately begin to tie the floor.

Technology of waterproofing the floor with roll materials

1. A damper strip is laid around the perimeter of the walls. It is necessary to compensate for the expansion of concrete screed under the influence of temperature fluctuations. Attach the damper tape with an adhesive layer or dowel-nails.
   

   Along the perimeter of the walls lay the damper tape

2. Align the base if necessary, rubbing the potholes with a cement-sand mortar or covering them with sand.
3. When using polymeric waterproofing film processing of concrete slabs, the primer is not needed. If desired, it is possible to treat concrete slabs with a solution for penetrating waterproofing. If a common ruberoid is used, the floor must be pre-treated with a primer for bitumen mastic.
4. When using polymeric waterproofing film processing of concrete slabs, the primer is not needed. If desired, it is possible to treat concrete slabs with a solution for penetrating waterproofing. If a common ruberoid is used, the floor must be pre-treated with a primer for bitumen mastic.
5. The roll-up waterproofing is spread over the prepared floor with stripes, forming an overlap on the walls not less than 15 cm. The stripes also overlap, the width is not less than 10 cm. When using a roofing material, it is glued to the base with bitumen mastic, and joints are formed which form an overlap.
   

   The process of laying the roll-up waterproofing

6. The welded materials, for example, glass-insulated, are fixed to the base with a gas burner. Polymer films are lapped and welded together by a construction hair dryer.
   

   Laying of fusible materials

7. The number of layers of waterproofing depends on the type of material: the roofing material is laid in at least two layers, the fusible films and polymeric materials in one layer. After laying the roll waterproofing, it is possible to perform reinforcement and screeding of the floor. After the screed hardens, the projected roll-up waterproofing and the damper tape are cut level with the floor.

1. waterproofing technology for the waterproofing of the floor The prepared concrete base is cleaned of debris, dust and contaminants, especially sharp particles, cutting edges and protrusions, as well as stains from oils, solvents, chemically active substances - when interacting with solutions of lubricating waterproofingthey can destroy it.
   

   Prepared concrete covering is cleaned from dust and dirt

2. The waterproofing is most often performed with bitumen or bitumen-rubber mastics of cold application. Prior to the beginning of the work, the surface of the floor is recommended to be primed with a primer for this type of mastic. It is better to choose the primer of the same manufacturer.
3. Primer is applied with a brush in one layer, lubricating all areas. It reduces the dusting of the surface and improves the adhesion of mastics to it. Especially carefully you need to handle the joints with the wall and the space around the pipes. The drying time of the primer usually does not exceed two hours.
   

   Primer application process in one layer

4. The mastic is applied with a broad brush or roller in several layers, each subsequent application after the previous one has dried completely. The layers are applied in a different direction of movement of the brush or roller. At the joints of the walls and near the pipes, the mastic is applied with a fine brush, carefully coating all the areas.
   

5. mastic application process The complete drying of the waterproofing coating usually lasts about two days. After that, you can start the screed. When laying the valve, it is necessary to use plastic guides to avoid contact of metal structures with coating waterproofing - they can damage it when loaded.

For reliable waterproofing of the floor before the screed, you can use not one but several methods. For example, when waterproofing a floor in a private house without a basement, you can make a gravel-sand pillow, lay a layer of insulation on top of it, a waterproofing film, and only then mount the reinforcement and fill the screed. In the apartment on the first floor, located above the basement, you can use penetrating waterproofing slabs in combination with a roll or slip waterproofing. In the wet rooms of apartments located on the upper floors of the apartment building, where any leakage may entail compensation for damage to neighbors, it is better to equip the double waterproofing: before and on top of the screed. In this case, roll materials are used for the screed, and an overlying waterproofing is applied over the screeds.