Preparing the base:
Clean concrete, masonry or old plaster from dust, check the old plaster for strength and adhesion to the base. Clean out potholes and pre-plaster them. Strengthen chalking and crumbling surfaces with KNAUF-Tiefengrund primer.
Preparation of the mortar mixture:
Mix the contents of the bag with water manually or using a drill with a mixing attachment. Leave for 15 minutes and stir again. Adding any materials is not allowed.
Application:
*When facing with insulating boards: apply KNAUF-Sevener solution around the perimeter, as well as in the middle of the insulating board in dots or in a continuous zigzag stripe. Bandwidth approx. 5 cm, thickness about 2 cm. Place the insulation board on the wall and level it. Further work with slabs, carry out after the solution has hardened (~48 hours).
*When reinforcing the surface of insulating slabs: if necessary, dowels are installed for additional fastening of the slabs. Using KNAUF-Sevener mortar, diagonally reinforce the surface of the insulating boards at the corners of all openings with strips of fiberglass mesh measuring ~30x50 cm, and install protective corners on the outer corners. Apply a KNAUF-Sevener solution with a thickness of ~5 mm to the surface of the slabs and level it, drown the reinforcing mesh into the fresh solution over the entire surface with an overlap of approx. 10 cm, while the solution should cover the mesh. Before continuing work, allow the reinforcing layer to harden and dry for 8 days.
*When leveling structural irregularities, apply KNAUF-Sevener to cleaned or prepared surfaces of old plaster in a layer of up to 10 mm. If necessary, lay reinforcing mesh.
*When plastering: apply KNAUF-Sevener with a thickness of 3-5 mm onto a concrete surface cleaned of dust and smooth it.
*Plastering bridge: on a smooth surface of concrete, aerated concrete, etc. Apply an intermediate connecting plaster layer of KNAUF-Sevener up to 10 mm thick, smooth it and after no less than 3 days apply the KNAUF-Grunband solution.
*When reinforcing the surface of plasters: apply KNAUF-Sevener over the entire surface with a layer of ~ 3 mm on a dry layer of plaster. Lay strips of reinforcing mesh measuring ~30x50 cm diagonally relative to the corners of all openings. Lay reinforcing fiberglass mesh over the entire surface with an overlap of 10 cm. The next day, once again apply a layer of Knauf-Sevener mixture ~2-3 mm thick. After the solution has set, rub the surface with a felt float.
*With additional reinforcement: in the case of making rubbed surfaces for painting in an external insulation system, it is necessary to re-apply the KNAUF-Sevener solution and lay a fiberglass mesh in it with the joints offset relative to the first layer. After acquiring the required hardness, apply another Knauf-Sevener solution with a thickness of ~2-3 mm to this layer and, upon reaching the appropriate hardness, treat with a felt or sponge trowel.
Both among professionals and among novice finishers, Knauf plaster mixtures are especially popular due to their quality, ease of application and a large assortment that allows you to choose the right composition for any type of work. One of them, Sevener plaster, will be discussed in great detail in this article.
The Knauf Sevener plaster-adhesive mixture is made on the basis of cement (see). Its composition also includes fractional sand, special fibers and modifying additives, which give it high ductility, water-repellent properties, crack resistance and other positive qualities.
Advantages of the Sevener mixture
Like all other Knauf plaster mixtures, this material is different high quality. And the special properties are given to it by the components included in its composition, mixed in optimal proportions.
So:
- Special fibers in combination with polymers and water-repellent additives give this product resistance to cracking and the ability to repel water, which protects the base and the insulation glued to it from the aggressive effects of moisture and prevents the occurrence of dampness in the room;
- Sand of a certain fraction in combination with adhesive additives and binders give it maximum strength, good adhesion to the base, and ductility.
Sevener Knauf plaster-adhesive mixture is characterized by economical consumption: depending on the type of work for which it is used, it is 3.5-7 kg/m2. That is, one 25 kg bag can be enough to finish more than 7 sq.m. surfaces. Considering that the price of the package is just over 400 rubles, the cost of repair and construction work turn out to be low.
Specifications
Application
Due to its unique properties, the Knauf Sevener plaster-adhesive mixture can be used with equal success for both external (see) and internal work.
Use Cases
Already from the name it is clear that this building mixture is universal and can be used both as plaster and as an adhesive.
It is intended for the following types works:
- Repair of old plaster of building facades, including structural surfaces and those coated with paints and varnishes, provided that they do not crumble and adhere firmly to the base;
- Application of thin-layer intermediate plaster on smooth concrete and structured surfaces of mineral plaster, on coatings based on artificial resins and surfaces with dispersion coating;
- Construction of a bonding plaster bridge on surfaces made of porous or smooth concrete;
- Bonding thermal insulation boards to the base mineral wool or expanded polystyrene when installing external thermal insulation systems;
- Installation of a protective layer on top of thermal insulation boards.
Please note. The coating created using the Severin mixture is an ideal basis for subsequent finishing with materials such as Goldband Knauf leveling plaster mixture or Knauf Diamant decorative plaster.
Depending on the method of application, the consumption of the dry mixture per square meter surfaces. For example, Severin Knauf dilutes the plaster mixture for gluing insulation to a flat surface at the rate of 3.5 kg/m2, and if masonry is lined with insulating boards, it will require 6 kg.
Likewise, plastering even surfaces requires less material (5 kg) than applying a layer to an old one. structural plaster(6-7 kg). Maximum consumption is also obtained when creating a reinforced protective layer on the surface of the insulation.
Features of application
Regardless of the type of work for which the Knauf Sevener plaster mixture will be used, the base must be carefully prepared, clearing it of crumbling particles, dirt and dust.
Then the solution is prepared; instructions for its preparation are available on the package. Typically, 5 liters of water are required to mix 25 kg of dry mixture.
For reference. Ready mix can be applied either manually or mechanized, for which continuously operating mortar-mixing pumps are used.
When applying it yourself, the amount of the prepared solution should be such that it can be completely used in 2 hours. After this time has passed, it will begin to lose its properties.
Work should be carried out when positive values air temperature and protect freshly applied plaster from frost, as well as from direct contact with the surface sun rays and drying too quickly.
Before continuing work and applying leveling or decorative Knauf plastering mixture, you need to wait for it to dry completely and coat it with Knauf Izogrund primer.
Conclusion
We deliberately did not describe in detail the process of working with this plaster: you will become familiar with it by watching the video in this article. By choosing this material, you will be satisfied with the quality of the result.
"Knauf-Sevener" is a modern dry mixture, which is produced using lime- cement based. It is intended for indoor and outdoor use. The ingredients include special fibers as well as polymer additives designed to provide high adhesion, water repellency and crack resistance.
General description
The manufacturing process of the described mixture is a combination of binders with adhesive additives, which provides increased strength to the finished layer and crack resistance, which is much higher compared to known solutions. The components contain a moisture-repellent additive that protects the thermal insulation layer or masonry from getting wet. The microclimate inside residential premises does not deteriorate, since Knauf-Sevener has a low resistance to water vapor diffusion.
This mixture should be used when constructing external thermal insulation systems for buildings for various purposes When gluing insulation boards to the base, they can be made of mineral wool, as well as expanded polystyrene. A reinforced fiberglass mesh can be attached to their surface, which is subsequently covered with decorative plasters.
For reference
The described can be applied to durable, structured and cleaned mineral-based plaster substrates. A dispersion coating or one based on artificial resins can be used as a rough surface.
Area of use
"Knauf-Sevener" is used for repairing cracked old ones and also as a solution for reinforcing mesh. The latter is laid on hardened plaster during masonry work using mixed materials. The mixture can act as an adhesive plaster for porous and smooth concrete surfaces. Sometimes Knauf-Sevener is laid in a thin intermediate layer on concrete surfaces. You can use a mechanized or manual method. In the first case, continuously operating high-performance pumps are used.
Specifications
Specialists and home craftsmen may be interested in compressive strength and bending strength; these parameters are 4.4 and 2.3 MPa. In a dry state, the mass reaches a density of 1400 kg/m3, and the density coefficient is 0.52. Since the mixture is used as an insulating layer, you may be interested in its thermal conductivity, which is 0.87 W/m °C. The absorption coefficient is less than 0.5 kg/m²·h.
Material consumption information
"Knauf-Sevener" technical specifications which are presented in the article may be useful to you if you plan to use it for repair work. The composition will be consumed in a certain amount, which depends on various factors. When covering insulating surfaces that are smooth and covered with old plaster, it will take 3.5 kg/m2. If you are facing insulation boards that are laid, then you will need 6 kg/m2. Putty can be used as a protective layer, which is applied to insulating boards; in this case, 7 kg/m2 will be needed. The average material consumption when plastering the old one will be 5 kg/m2.
Reviews about the technology of use
“Knauf-Sevener”, reviews of which are often very positive, must be applied using a certain technology. According to users, you first need to prepare the base, then you can start mixing the solution. The next step is the application itself. If work is carried out under special conditions, then fresh plaster must be protected from rapid drying and exposure low temperatures. As buyers emphasize, the decorative layer can be applied only after the plaster layer has completely dried.
System TN-FACADE Decor 1 - outer wall; 2 - strengthening primer (if necessary); 3 - glue for thermal insulation boards; 4 - insulation from stone wool Technofas Cottage; 5 - disc-shaped facade dowel; 6 - base plaster-adhesive reinforcing layer; 7 - fiberglass mesh; 8 - quartz primer; 9 - decorative plaster; 10 - facade paint (if necessary). Photo: TECHNONICOL
Majority large manufacturers thermal insulation materials and construction mixtures are offered efficient systems insulation of building facades. One of the most popular in private housing construction consists of (expanded polystyrene or mineral wool), which are attached to the walls special glue and dowels. The outer layer of the fixed insulation is first protected with a plaster-adhesive composition reinforced with a special fiberglass mesh, after which a decorative coating is applied.
Living in a house insulated in this way is comfortable. The costs of heating and air conditioning are reduced, and the façade takes on a new, original look.
The maintenance-free service life of the system is at least 25 years. In its multilayer design, there are practically no rigid connections that could become cold bridges. Heat losses through dowels are so insignificant that they are not taken into account in thermal calculations.
Types of adhesive mixtures
Universal glue
Polyurethane adhesive Fastfix (Penoplex) (750 ml pack - 300 RUR). Polyurethane adhesive Ceresit CT 84 (Henkel) (850 ml pack - 550 RUR). Foam adhesive for polystyrene foam (TECHNONICOL) (750 ml pack - 326 RUR). Photo: Penoplex, Henkel, TECHNONICOL
To an inexperienced buyer, it seems that a façade insulation system requires mixtures of two types. The first is adhesive, for fixing insulation boards to the wall surface. The second is plaster and adhesive, to create a base layer under. Having studied the assortment, he understands that there are special adhesive and plaster-adhesive mixtures on the market, designed for a specific type of insulation (expanded polystyrene or mineral wool), and universal ones. If craftsmen do not have time to complete construction work with the onset of cold weather, then they will have to use “winter” modifications of these compounds.
Installation of facade thermal insulation systems begins after completion of internal wet work and drying of the building, as well as installation of window and door units.
Works with plastering glue mixture carried out at air and base temperatures from 5 to 30 °C. Photo: ShutterStock/Fotodom.ru
Taking into account all the nuances of the construction process, from unevenness of the base to the timing of work, and accurate calculation of the quantity consumables seem like an impossible task. However, leading manufacturers of dry mixes have taken these circumstances into account. In order not to have to worry about choosing and calculating the volume of required dry mixtures, they suggest choosing one - universal. Essentially, it's glue and plaster rolled into one. The composition equally successfully fixes polystyrene foam and mineral wool slabs to the base and forms a reliable and durable base layer.
How to prepare the mixture
The cement-based plaster-adhesive mixture contains sand of different fractions, reinforcing fibers and polymer additives. The distributed adhesive solution provides sufficient adhesion to the base, and the base layer is durable, resistant to cracking, and has good water-repellent properties.
The manufacturer guarantees the beneficial qualities of the mixture only when it is proper preparation. Pour the amount indicated on the package into a large container (at least 25 l). clean water room temperature. Then the plaster-adhesive composition is gradually added to the water, constantly stirring the mass with a mixer or drill with a special attachment so that lumps do not form. Moreover, they act only in this sequence, and not vice versa. The mixer rotation speed should not exceed 400–800 rpm (as recommended on the package), otherwise the mixture may separate. After a technological pause (5 minutes), which is necessary for the solution to mature, it is mixed again. If it becomes thicker during operation, the consistency is restored by repeated stirring. You cannot add water to the mixture.
At the corners of windows and doorways Thermal insulation slabs should not form continuous horizontal or vertical joints. In these places, slabs with an angular cutout are installed. Moreover, they are positioned so that the joints of the seams with the adjacent elements are at a distance of at least 150 mm from the corner of the opening. Photo: Saint-Gobain
Polyurethane glue
Polyurethane glue in a can - effective remedy fastening of thermal insulation boards made of extruded and foamed polystyrene foam. The composition has high adhesion to plastered substrates, as well as surfaces made of metal, brick, wood, stone and various concretes. The glue in the bottle does not take up much space and is easy to deliver to the site. It is convenient and easy to use and does not require any special skills. There are no dusty or dirty preparatory work necessary when mixing dry plaster-cement mixtures with water. The only limitation is that the insulation material is only polystyrene foam.
Under no circumstances should the reinforcing mesh be laid directly on the thermal insulation layer. It should be inside the plaster-adhesive layer and in correct position not visible on its surface.
Compared to dry mixtures, adhesives from a balloon reduce transportation and storage costs, reduce time and labor intensity installation work. The material is very economical: one cylinder is enough to fix 6–12 m² of slabs. Photo: Henkel
How to apply glue
A cement adhesive solution is applied to the surface of the insulation boards in different ways depending on the unevenness of the base. Beacon is used for wall unevenness of 5 mm or more. The mixture is distributed around the perimeter of the slab and laid out with several beacons in the center. Solid is used on surfaces with unevenness up to 5 mm, using a notched trowel. In both cases, the surface of the mineral wool insulation is pre-primed with a thin layer of the same adhesive solution. After installing the element, excess glue extending beyond its contour is removed.
After installing the slab in the design position, the adhesive contact area must be at least 40% of the bonded surface. Photo: KNAUF
To create a protective reinforced layer, the glued insulation is covered with a plaster-adhesive composition 2–3 mm thick. Then the fiberglass mesh sheets are embedded in it and the mixture is applied again to a thickness of up to 3 mm, smoothing it so that the mesh is not visible. Surface unevenness is leveled with an abrasive float after 24 hours.
Preparing the base:
The base must be dry and durable. Brickwork, concrete bases and mineral plasters must be cured for at least 28 days. Before applying the plaster-adhesive mixture, it is necessary to remove crumbling elements, oil stains, snow, ice, frost and other contaminants from the surface of the base that prevent the adhesion of the material to the surface. For pre-leveling surface and to eliminate significant unevenness, it is recommended to use appropriate leveling plaster. To enhance the adhesion strength of the material to the base, treat the surface with appropriate primer. The surface is ready to apply the material only after the soil has completely dried. When the work temperature is below +5°C, priming is not performed. In this case, the base must be thoroughly cleaned with a brush.
When performing work using extruded polystyrene foam, before gluing and before applying the base plaster layer, the surface of the slab must be roughened mechanically.
When subsequently installing a reinforced base plaster layer, thoroughly clean the surface of the heat-insulating boards from dust with a brush.
Preparation of the solution:
Before use, the dry mixture must be kept at a temperature above 0°C for at least 24 hours. Also, before starting work, all elements of the insulation system must be kept at positive temperatures. To prepare the solution, it is recommended to use water at a temperature of +10 to +30°C. With constant stirring, pour the contents of the bag into a container with clean water at the rate of 0.18-0.22 liters of clean water per 1 kg of dry mixture (for 1 25 kg bag – 4.5-5.5 liters of water) and mix until homogeneous mass. Mixing is done mechanized (professional mixer) or manually. The solution must be kept for 3-5 minutes, then mixed again. After this, the solution is ready for use.
The solution can be used within 1 hour from the moment of mixing with water. When the viscosity of the solution in the container increases (within the pot life time), it is necessary to mix it thoroughly without adding water.
To prepare the solution, use only clean containers, tools and water.
Execution of work:
Fastening of thermal insulation boards:
The adhesive solution can be applied to the surface of the insulation in various ways. If the base is uneven with a depth of more than 3 mm, the adhesive solution is applied to the surface of the insulation using a trowel along the perimeter of the slab in a continuous strip, as well as dotted in the center. The width of the continuous strip is 3-4 cm, the thickness of the adhesive layer is about 20 mm. If the base is uneven less than 3 mm, the adhesive solution is applied using a notched trowel or trowel evenly over the entire surface of the slab.
Immediately after applying the adhesive solution, the plate is applied to the surface and pressed tightly. The plate adjustment time is 15 minutes. The insulation boards are attached in one plane, with T-shaped dressing of the seams, close to one another. The gap between the plates is no more than 2-3 mm. Subsequent work on installing dowels and laying out the base layer can be done no earlier than after 2-3 days.
Construction of a reinforced base plaster layer:
Using a notched trowel or trowel, the plaster-adhesive solution is applied in a thin layer to the surface of the slab and distributed evenly. Reinforcing facade fiberglass mesh (with an overlap of at least 10 cm) is laid on a freshly applied plaster layer, “sinked” into it and smoothed so that the mesh is in the middle of the base layer.
During operation and in the next two days the temperature environment and the base should not be lower than -10ºС. At temperatures below -10 ºС, all work should be carried out in a thermal circuit. During the hardening process, the surface must be protected from intense drying: avoid exposure to direct sunlight, water and drafts. Application decorative plasters, paint and varnish materials and finishing by others decorative coatings are made no earlier than 7 days after the creation of the reinforced base layer.