Screed waterproofing methods, materials used, work methods, pros and cons of waterproof coatings. Floor screed waterproofing protects concrete from moisture and aggressive substances (salts, alkalis, acids) present in it. Work is carried out before the base is poured with cement mortar and, if desired, after it has hardened. The main ways to solve the problem and the technology of work will be discussed in this article.
Features of screed waterproofing works
Waterproofing the base is necessary to prevent water from entering the concrete components, which can lead to cracks and structural failure. It refers to mandatory operations that are performed at the initial stage of construction and during major repairs. The procedure is performed in all types of buildings - mansions and multi-storey buildings.
The simplest option for waterproofing the floor screed is to equip a gravel-sand cushion, but it only protects against capillary rise of water and is used in the case of a deep location of subsoil waters. Systems using roll materials or special mastics are considered more reliable. The modern methods of protective coating include impregnating agents. Systems of several types of waterproof partitions are often created.
Protection methods depend on the location of the screed and the functional purpose of the room. The floors in rooms with increased humidity and where direct contact with water is possible - in the bathroom, toilet, kitchen, boiler room require increased attention. In these places, the floor is protected from two sides: from below, from damp vapors or from capillary moisture, and from above, from water leaks from the room.
Advantages and disadvantages of screed waterproofing
The procedure allows you to solve many flooring problems, the main ones can be formulated as follows:
- Once the appropriate operations have been carried out, wet steam from the basement or moisture from the soil will not be able to interact with the floor components. Water often contains various acids and alkalis, which have a negative effect on cement. After a few years, the concrete will crack and begin to crumble under the influence of active elements.
- The waterproof coating keeps the base in its best condition for a long time.
- A modified floor will protect the neighbors on the lower floors from accidental water leaks and save your finances from compensating your neighbors.
- After pouring, the concrete will harden evenly. Insulation will not allow water to quickly go down, and after a certain period of time a durable layer will form. Otherwise, if the percentage of liquid decreases sharply, the coating will crack and collapse.
Hosts should be aware that waterproof casings are imperfect and have disadvantages. For example, the film is not strong enough, gluing materials require special conditions for laying, and bitumen has a short service life.
Choice of waterproof material
The base of the floor is protected from moisture by gluing, painting or coating waterproofing.
The gluing method involves the use of roll insulators. Film products are made from PVC, rubber, polypropylene and other synthetic samples, which are supplemented with additives to increase strength, elasticity, durability, etc. Their thickness ranges from 0.2 to 2 mm. Selected models are reinforced with fiberglass for improved performance. The pieces cut to the size of the room, increased by 300-400 mm, are laid on the floor and on the walls with an overlap. The joints between the cuts are sealed, creating a waterproof bowl. The most economical option is PVC film.
Gluing waterproofing is also performed using roofing material, fiberglass, etc. These are roll products coated with bitumen and sealant. By the method of fastening to the floor, they are divided into weldable and fixed. In the first case, for fixing to the surface, the canvas is heated with a blowtorch, in the second, fastenings are performed mechanically using special equipment.
Plaster penetrating waterproofing involves the use of solutions from Portland cement, sand and components from chemically active elements that react with concrete and fill its pores and microcracks. It is divided into penetrating agents and leveling mixtures. In the first case, after application, the plaster is poured with water for several days to activate the reaction. The formed crystals retain water, but do not impede the movement of air currents. When microcracks occur, reagents are spontaneously generated that eliminate the defect. The leveling compounds contain special components that harden after being applied to the screed and create an airtight shell.
Coating waterproofing not only covers the surface, but also connects the individual parts of the "pie". The most commonly used bitumen-rubber or bitumen-polymer mastic, which is applied in two layers. Unlike pure bitumen, the mastic is elastic, durable and does not crack over time. Multicomponent samples are much more expensive than pure bitumen, but more durable and more resistant, which allows their use in extreme conditions. For example, formulations with antibacterial components have worked well in bathrooms.
In addition to mastic, other means are also used, for example, sealants. Before use, they do not need to be heated to a liquid state, and after application they quickly harden. The disadvantages of this method include low mechanical strength and low resistance to hydraulic pressure.
Floor screed waterproofing technology
Each product is applied to the base using its own technology. Below are instructions on how to use the most popular materials and how to buy them. The choice of the method of covering the screed with waterproofing is made taking into account the properties of the material, the purpose of the room, the environment and other conditions.
Gravel-sand pillow
The variant is usually found in private houses without basements. Due to the presence of air between the components of the "cushion", the water does not rise through the capillaries to the screed. Activities are carried out both at the stage of preparation for construction, and after many years of operation of the house. The work is carried out in the following sequence:
- Remove fertile soil with organic impurities from the site for the future foundation. Align it with the horizon.
- Fill in a 200 mm layer of crushed stone and level it, eliminating large differences. If the groundwater is close to the surface, increase the thickness to 500 mm. The stones should be no more than 50 mm.
- Tighten the pillow.
- Fill the gravel with coarse sand in a layer of 100-400 mm and level it. Tamp the sand by sprinkling water over it periodically.
- Fill the "cake" with concrete screed.
The design does not save from wet fumes, therefore, before pouring the solution, it is recommended to perform the following operations:
- Lay sheets of geotextile on the base to protect the upper layers from mechanical damage. Connect the joints by heating the edges with a building hair dryer.
- Cover the geotextile with polystyrene, polystyrene foam or other foam insulation. Discard foam due to low mechanical strength.
- Place the plastic wrap on top with an overlap of 15-20 cm on the wall and adjacent pieces.
- Attach an expansion tape to the partitions to prevent the screed from touching the walls. It will ensure the expansion of the layer when heated. Fix the strips with glue or nails.
- Fill the floor with concrete.
Semi-dry screed waterproofing is carried out in a similar way.
Wrapping waterproofing
This method is usually used when there is a rigid base to which it is possible to glue the roll covering. To create a water-impermeable barrier in multi-storey buildings, it is laid directly on the floor slabs.
The sequence of operations is as follows:
- Examine the surface for irregularities. Remove protrusions, rub out gouges and crevices with cement mortar or cover with sand.
- Cover slabs with a deep-penetrating primer or penetrating waterproofing agent.
- If you plan to use roofing material, treat the flooring with a primer.
- Unwind the roll and cut the canvas into pieces according to the size of the room, adding 30-40 cm.
- Lay the strips on the floor with an overlap of at least 15 cm on the wall and on adjacent pieces with an overlap of 10 cm. Connect the joints in any way suitable for this type of product. If using roofing material, heat the edges with a blowtorch and press them together. Fasten the glass insulation to the base using a gas burner. To increase reliability, the material can be laid in several layers.
- Fill the area with concrete. After it has hardened, trim off the excess damper and blade flush with the base.
In multi-storey buildings, it is recommended to perform double waterproofing of the concrete screed. Roll products are laid on the floor slabs, which are poured with concrete. From above, the surface is lubricated with mastic.
Roll waterproofing
The simplest representative of this class is plastic wrap. Cover the base in one piece if possible.
An obstacle impervious to water is formed as follows:
- Remove all sharp elements from the surface, because the film does not have high mechanical strength.
- Cut sheets that are 300-400 mm larger than the length of the room.
- Lay the material on the floor with an overlap of 150-200 mm on the walls. Cover the adjacent strips by 100-150 mm, and seal the joints with reinforced tape. If the screed is formed using self-leveling floors, the joints may not be glued due to the waterproofness of such compounds.
- Further work is carried out as in the previous section.
Coating waterproofing
It is carried out with bitumen mastic or sealant in several layers. It does not require smoothing the surface, which is very convenient when working in openings with a large number of pipelines.
The work is done as follows:
- Pour the base with concrete, wait until it hardens completely.
- Clear the area of debris. Remove sharp protrusions. Remove stains from oil, solvent and other substances that can react with the components of the lubricant. If they remain, the structure will quickly collapse.
- Cover the screed with a special bitumen primer - primer. It is recommended to buy bitumen and primer from the same manufacturer. The agent will reduce dusting and increase the adhesion of concrete with mastic. Especially carefully treat areas near walls and pipes.
- Prepare the mastic according to the manufacturer's instructions.
- Using a brush and roller, apply the substance over the entire surface in several layers, each subsequent coat is smeared after the bottom has dried. Move the instrument in different directions during the procedure. Use a thin brush near pipes and other awkward places.
- After the mastic has completely dried (after 2-3 days), the floor can be poured with concrete mortar. If reinforcement is used, use plastic guides to prevent metal-to-mastic contact, which could damage the protective layer.
One of the varieties of coating waterproofing is called painting. It is carried out using bitumen or polymer paints and varnishes. The product is applied cold or hot.
Impregnating waterproofing
A special agent is used, which, after application, penetrates through the pores in the concrete, and then crystallizes and fills all microcracks.
The work is done as follows:
- Prepare the mixture according to the instructions provided by the supplier of the product. The finished solution looks like a conventional cement emulsion.
- Use a brush or putty knife to cover the area with the product. The thickness of the mixture depends on the purpose of the room. The higher the humidity, the more plaster needs to be applied. Spread the floors of the bathroom or kitchen with three balls of the product; in other rooms, the overlap is treated 1-2 times. Each subsequent layer is applied perpendicular to the lower one.
Features waterproofing screed in problem areas
To protect the floors in the bathroom, toilet and boiler rooms from moisture, it is recommended to use dense materials: roofing material, rubitex, bitumen.
Waterproofing of a cement screed in such rooms is mandatory, regardless of the thickness of the screed and the composition of the topcoat. The sheets are laid with an overlap on the walls 20-30 cm and between themselves 20 cm. The roofing material in the corners is neatly folded and fastened with a stapler, it is not allowed to cut.
The laying of roofing material is accompanied by hot work with the release of a large amount of smoke. Therefore, it is carried out at the initial stage of construction so that there are no problems in living rooms.
If, during operation, water gets from your apartment to the lower floors, then, most likely, the protective shell is damaged. In this case, it is necessary to completely remove the screed and restore the waterproofing.
Roofing material in living rooms is not laid due to the use of a blowtorch and toxic smoke, so you need a plastic wrap. In the store, you can buy a canvas wide enough to cover the entire area in one piece. Instead of roofing material, you can also use bituminous mastic or melted bitumen, which covers the base before pouring.
Watch the video on screed waterproofing:
Screed waterproofing is considered an important point in the arrangement of the flooring, because not only the fate of the floor is at stake, but also the relationship with the neighbors of the lower floors. Therefore, this type of construction work must be treated not as the next stage, but as the most important one.
