All about three-layer wall panels: types and application features

Three-layer wall panels are a new development in construction engineering. It is aimed at the qualities of a material characterized by increased strength. Due to their layering, they were called sandwich wall panels. Along with external decoration of facades, they are also suitable for interior decoration of houses.

Choosing wall panels

1.1. Metal cladding

The cladding is galvanized steel sheet with a protective and decorative paint coating in accordance with GOST 14918-80, GOST R 52246-2004.

When renting sandwich panels, the standard metal thickness is 0.5 mm. On request, it is possible to use steel sheets with a thickness of 0.45 mm, 0.6 mm, 0.7 mm.

Table 1. Technical characteristics of steel for sandwich panels.

1.2. Polymer coatings

Structure of steel sheet with polymer coating:

Types of coatings:

Polyester – polyester coating. Suitable for external and internal work. Resistant to weathering and corrosion. Suitable for all climate zones.

Coating thickness - 25 microns.

Pural – polyurethane coating. It is practically not subject to mechanical stress, ultraviolet radiation, or chemically active components, which ensures a long service life, does not lose color, and the integrity of the coating. Coating thickness 25 microns. Suitable for external and internal work.

PVDF – polyvinyl difluoride coating. The coating consists of 80% polyvinyl fluoride and 20% acrylic. Advantages of the coating: high anti-corrosion properties, resistance to weathering and pollution, suitable for outdoor use in any conditions. Retains its properties in the temperature range from -60°C to +120°C and has good ductility.

Plastisol (PVS) – polyvinyl chloride coating. It has excellent ductility and is resistant to scratches, corrosion and environmental influences. Recommended for use in harsh operating conditions and polluted environments. In addition, Plastisol can significantly improve the appearance of the facade. Coating thickness 200 microns.

Table 2. Types of polymer coatings for metal skins of sandwich panels.

Repair of such buildings

The need for repairs may arise, most often, due to mechanical stress on the panel. Sandwich structures will need to be repaired in the following cases :

• 
  Visible damage to the facade (scratches, dents). This will require cleaning the damaged area, puttingty and painting the surface. Work must be done as quickly as possible so that the wall panel does not absorb moisture.

• The need to dismantle corners, flashings or flashings. Using a special construction tool, remove the necessary parts, replacing them with new ones.

The technology for carrying out repair work is selected individually in each specific case. The stages may be as follows :

1. Sanding the damaged area with an abrasive material.
2. Using a surface degreaser.
3. Puttying the treated area flush with the surface to be repaired.
4. Drying time for the putty (1 day or more, depending on atmospheric temperature).
5. Sanding the surface with fine sandpaper until the wall is smooth.
6. Applying a layer of two-component primer.
7. Drying of the primer (up to 6-12 hours).
8. Painting the panel in the required color.

The repairman will need spatulas, sandpaper of different grain sizes, brushes for primer and paint, putty, primer and paint. It is quite possible to repair a wall in 2 days . If the building has several floors, or repairs are required at a high altitude, an industrial climber is invited to perform all the necessary work.

If it is necessary to replace corners and strips, then purchase a fastening element and new corners (or strips, if they are replaced). Old hanging fasteners are removed. Use a drill, screwdriver, self-tapping screws, bolts, screws, anchors, depending on the required area to be repaired and the purpose of the wall - interior, exterior.

Sandwich panels that are too deformed are replaced completely, so their repair is useless.

1.3. Color solutions

Standard colors according to the RAL catalog used in the production of SteelPanel, Polyester coating:

It is possible to produce sandwich panels in non-standard colors. When choosing non-standard colors, metal painting is carried out to order, which increases the delivery time of sandwich panels.

When choosing a color scheme, you need to take into account that darker colors are more susceptible to surface heating, which can lead to thermal deformations (swelling of the skins between fastenings, the formation of folds on the metal at fastening points). When choosing dark colors, it is not recommended to use a three-span fastening scheme.

At the same time, light colors have greater reflectivity. Light surfaces are not subject to overheating, which preserves the surface of the sandwich panel in its original form.

1.4. Insulation materials

Metal sandwich panels are produced with two types of insulation: basalt mineral wool and expanded polystyrene.

Basalt mineral wool is a thermal insulation material based on basalt, also called stone wool. Cotton wool has a fibrous structure, so the spaces between the fibers are filled with air and provide high thermal insulation characteristics.

To ensure rigidity, sandwich panels use so-called lamellas. The mineral wool slab is cut into strips of the required width and unfolded when fed into a line perpendicular to the metal casings (cladding). Due to this direction of the wool fibers, the required compressive strength of the finished sandwich panel is achieved.

The main advantages of mineral wool are low thermal conductivity, environmental friendliness, flammability group NG, and resistance to chemical influences.

Table 3. Thermophysical and mechanical properties of basalt mineral wool.

Expanded polystyrene is a thermal insulation material based on styrene. Produced by foaming (filling with air) styrene granules. Due to good air filling, it has high thermal insulation characteristics. It is light in weight but has fairly good rigidity.

In sandwich panels, expanded polystyrene is laid in ready-made sheets, the sheets are pressed tightly.

The main advantages of expanded polystyrene are moisture resistance, low thermal conductivity, environmental friendliness, and when treated with a fire retardant, it can be classified as low-flammable (group P).

Table 4. Thermophysical and mechanical properties of polystyrene foam.

All insulation materials used in the production of sandwich panels are certified and do not pose a danger to humans and the environment.

1.6. Protective mounting film

To protect the polymer coating from light mechanical damage (scratches) during transportation, loading and unloading, installation, a protective mounting film is applied to the surface of the sandwich panels. After completing the installation work, the film is removed.

IMPORTANT! Instructions for using protective film:

1. Protective film is designed to protect surfaces from damage and contamination during transportation and installation, as well as from mechanical stress during processing (bending, cutting, shaping, stamping)

2. All declared technical characteristics of the protective film are valid in the range of 20 degrees Celsius. This temperature is mandatory both for the film itself and for the surface to be coated at the time of application. The optimal storage temperature is 15-30°C.

3. If the film is exposed to unfavorable conditions for a long time (temperature changes in a range other than operating ones; aggressive environment, etc.), its properties may be lost.

4. Surface treatment with all types of solvents is not allowed.

5. The film is applied under production conditions and removed immediately after installation of the product.

6. Storing surfaces with applied film in direct sunlight is unacceptable, because may cause changes in the properties of the adhesive, which will lead to difficulties when removing the film from the product.

7. To ensure that no fragments of the protective film or adhesive remain on the surface, the film must not be removed at very low (not lower than -10°C) or very high air temperatures (not higher than 40°C).

8. The shelf life of products with applied film is no more than 1 month.

9. All stated requirements are recommended by the manufacturer of this type of film.

Attention!

If the conditions for storing and using the protective film have been violated and the film is difficult to peel off, you can locally, at a temperature of approximately 60 degrees, quietly use a technical hair dryer. If the film has been on the product for a long time, and after its removal there is glue left, then it can be removed with industrial alcohol, but in no case with a solvent.

When using a solvent, not only the protective film is damaged, but also the polymer surface of the sandwich panel.

Construction technology

Before starting the installation of walls, the products are cleared of packaging, the ends of the slabs and the presence of lock connectors are checked.

If the insulation protrudes beyond the slab, this defect is removed with large construction scissors and coated with universal construction glue. Also, when preparing for installation, it is necessary to check the presence of waterproofing for the base and floor.

Then the technology for installing the slab is carried out as follows :

1. Cleaning the supporting base from dust and dirt.
2. Installation of a metal frame, the surface of which is treated with an anti-corrosion substance.
3. Installation of butyl and strong sealing tape (2 products) along the top of the base, along the guides that are connected to the frame with a special dense element (polypropylene or mineral wool tapes), along the outside of the plank, with a slight overlap (10 cm).
4. Establishing the level and installing the first panel strictly along the marked line, from the top, at a pitch of 400 (mm).
5. If installation is carried out horizontally, then the panels are fixed with the grooves down.
6. Here you need to treat the locking mechanism with sealant, while simultaneously filling the seam, which will be sealed with a cord (butyl rubber, with a diameter of up to 8 mm).
7. After connecting the panels, lay the transverse joints with an additional layer of insulation, 2 (cm) thick.
8. Then the connected part of the panels is sealed with sealant tape and covered with a building element (shaped), which must be laid with an overlap (5-8 cm).

After installing the panels and connecting them to each other, they must be screwed to the metal structure with self-tapping screws and secured with airtight seals .

During work, it is best to cut metal panels with a circular saw, according to the place marked with a pencil and a construction tape, while OSB or plastic panels are cut with a hand saw, chainsaw or jigsaw.

Full article on the ins and outs of building their sandwich walls here.

2.1. Characteristics tables

Table 5. Characteristics of wall sandwich panels with mineral wool insulation.

Table 6. Characteristics of roofing sandwich panels with mineral wool insulation.

Table 7. Characteristics of wall sandwich panels with polystyrene foam insulation.

Table 8. Characteristics of roofing sandwich panels with polystyrene foam insulation.

2.2. Soundproofing

Table 9. Sound insulation characteristics of wall and roof sandwich panels with mineral wool insulation.

Rw – airborne noise insulation, is a standardized parameter for the sound insulation of internal enclosing structures of residential and public buildings, as well as auxiliary buildings of industrial enterprises.

Ra – which represents the insulation of external noise produced by the flow of urban traffic, is a standardized parameter for the sound insulation of external enclosing structures.

Standardized parameters are regulated:

— SP 51.13330.2011 “Protection from noise”,

— SNiP 03/23/2003 “Protection from noise”,

— SP 23-103-2003 “Design of sound insulation of enclosing structures of residential and public buildings”,

— GOST 27296-87 (ST SEV 4866-84) “Noise protection in construction. Sound insulation of enclosing structures. Measurement methods".

New material for facades

The new product passed tests for compliance with standards and took its place among other building materials. If we consider the wall panels in terms of dimensions, their width ranges from 280 to 300 mm, and their length is up to 6 meters.

The material includes a reinforced concrete base, which performs load-bearing functions, a layer of thermal insulation and a decorative layer, which does not require plaster and is completely suitable for painting or wallpapering.

The structure is secured using steel elements welded to the embedded elements. As a result, three-layer reinforced concrete wall panels have increased strength and resistance to stormy weather, climatic anomalies, and vandalism. The new development is currently widespread, in demand and popular. The photo is strong proof of this.

The service life of the panels is more than 30 years. Other advantages include pronounced resistance to rainy weather and fire.

2.3. Load bearing capacity

Bearing capacity is the maximum load without loss of functional qualities that a structure, its elements, as well as foundation soils can bear.

The load-bearing capacity was calculated in accordance with SP 20.13330.2011 “Loads and impacts”.

Wall sandwich panels

Calculations of the load-bearing capacity of wall sandwich panels take into account that tightly glued insulation helps distribute stress under loads and absorbs shear forces, while metal sheathing is subject to tension and compression.

The calculation does not take into account possible changes in the shape of the panels (cutouts, cut edges, etc.). Limit states of load-bearing capacity have been calculated for wall panels. The values ​​indicated in the tables are reference material and must be calculated when carrying out design work.

Calculations were carried out taking into account the following simplifications and assumptions:

— the thickness of the sandwich panel is indicated by the thickness of the insulation,

— thickness of metal casings 0.6 mm,

— the width of external supports is at least 40 mm,

— the width of the internal supports is at least 70 mm,

— permissible deflection of the panel 1/100 L span,

— when determining the maximum deflection, the temperature difference between the outer and inner metal cladding t=55°C is taken into account.

Table 10. Design load-bearing capacity of wall sandwich panels with mineral wool.

Fig.1. Graph of the load-bearing capacity of wall sandwich panels with mineral wool under a uniformly distributed load. The loading scheme is single-span.

Table 11. Calculated load-bearing capacity of wall sandwich panels with expanded polystyrene.

Fig.2. Graph of the load-bearing capacity of wall sandwich panels with expanded polystyrene under a uniformly distributed load. The loading scheme is single-span.

Advantages and disadvantages of three-layer material

The advantages of using sandwich panels are:

1. Wide range of construction projects:
   industrial (hangars, warehouses, areas for production needs);
2. public and domestic (retail outlets, change houses, office premises);
3. motor transport (refueling, washing, repair);
4. sports (training halls, ice rinks and skateboarding);
5. agricultural purposes (poultry and animal premises);
6. sanitary (medical buildings of various types);
7. refrigerators (low-temperature storage areas).
8. High degree of fire safety. The panels belong to the “NG” group, which is considered non-flammable due to a special production technology. They cannot catch fire on their own. In the event of a severe fire, they are able to withstand the heat load, up to a massive fire, for 2 hours.
9. Environmental friendliness. Made from pure natural materials that do not cause allergies in people.
10. Light weight. Ease of installation contributes to the completion of construction in the shortest possible time. The slabs are easy to install, thanks to the lock connectors from the manufacturer.
11. Positive characteristics:
    high moisture resistance;
12. strength and reliability;
13. good insulating qualities (sound, extraneous noise);
14. small thickness (within 40-200 mm).
15. High level of thermal insulation, allowing you to create a reliable protective layer of the wall in low winter temperatures.
16. Easy to maintain and no need for decorative finishing.
17. Variety of decorative designs (a wide variety of different shades and patterns on the slabs.
18. Affordable prices for products that allow you to get a warm room for little money.

The disadvantages of sandwich panels are:

1. Strict compliance with the requirements for wall installation, in accordance with the rules of GOST and SNiPs.
2. Fragility of the structure due to careless operation. It requires careful handling, as it cannot be repaired, but needs to be replaced with a new product.
3. Special design requirement. Since it is self-supporting, it should not be subject to additional loads.

Judging by the listed description of the qualities of the plates, the advantages of using them are much greater than the disadvantages.

The outer part of the slabs is rarely damaged, especially during transportation to the construction site. But, if this happens, the scratch can be easily covered with a dye of a suitable color.

Additional information about the pros and cons is here.

Roof sandwich panels

Calculations of the load-bearing capacity of wall sandwich panels take into account that tightly glued insulation helps distribute stress under loads and absorbs shear forces, while metal sheathing is subject to tension and compression.

The calculation does not take into account possible changes in the shape of the panels (cutouts, cut edges, etc.). Limit states of load-bearing capacity have been calculated for wall panels. The values ​​indicated in the tables are reference material and must be calculated when carrying out design work.

Calculations were carried out taking into account the following simplifications and assumptions:

— the thickness of the sandwich panel is indicated by the thickness of the insulation,

— thickness of metal casings 0.6 mm,

— the width of external supports is at least 60 mm,

— the width of the internal supports is at least 80 mm,

— permissible deflection of the panel 1/100 L span,

— the calculation takes into account the panels’ own weight and a concentrated load of 100 kgf in the middle of the span

Table 12. Design load-bearing capacity of roofing sandwich panels with mineral wool

Fig.3. Graph of the load-bearing capacity of roofing sandwich panels with mineral wool under a uniformly distributed load. The loading scheme is single-span.

Table 13. Design load-bearing capacity of roofing sandwich panels with expanded polystyrene foam

Fig.4. Graph of the load-bearing capacity of roofing sandwich panels with polystyrene foam under a uniformly distributed load. The loading scheme is single-span.

Average price on the market

In the Russian Federation, the average cost of products by type can be approximately with a thickness of 100 (mm):

1. Walls for industrial buildings – from 1000 rub./m2.
2. Roofing – from 900 rub./m2.
3. Wall for residential premises - from 1200 rub./m2.

The required number of panels is calculated according to the house design. It is best to entrust it to professional specialists - masters of their craft.

In the calculation they will take into account:

• total area of ​​the house;
• height and length of walls;
• number of storeys;
• the shape of the pediments;
• attic;
• will add a percentage increase in products (+15%);
• will take into account the presence of interior partitions in the plan, with the distribution of panels.

An online calculator for calculating sandwich panels can be found here.

Read more about prices and construction calculations in this article.

2.4. Selection of span length depending on temperature

Due to the difference in temperatures between the outer and inner surfaces of metal sheets, swelling (warping) of the skins may occur in places of greatest stress. Most often this happens on the sunny side of buildings. Moreover, the temperature of the skin heated by the sun largely depends on the color and its reflectivity. All colors are conditionally divided into three groups with different properties (see table 12).

In order to avoid deformation of the metal skins of panels that are regularly exposed to the sun, it is necessary to limit the span length in such a way that the metal stress arising during operation is less than the maximum permissible values. The maximum span lengths for a continuous fastening scheme are indicated in Tables 13, 14.

Table 12. Groups of metal colors by reflectivity.

Table 13. Maximum span lengths of wall sandwich panels

Table 14. Maximum span lengths of roofing sandwich panels

Installation time

The approximate time frame for the construction of walls made of sandwich panels, for example, by a professional construction company, with the availability of the necessary tools, equipment and transport, will be the following period :

• Drafting and approval of the project – up to 1 month.
• Construction of the foundation (depending on the option chosen and agreed upon with the engineer):
  tape – 5-7 days;
• Reinforced concrete pile – 1-2.
• Manufacturing and transportation of panels of the required size takes 5-6 days.
• Construction of the walls of a house, for example, with an area of ​​120 m2, takes up to 3-4 weeks.

Total : the overall result of the work was approximately 2.5 months. If the future owners of the building want to build a reliable building that should last more than 30 years, then, according to building codes, the foundation must be given time to shrink.

For a strip foundation, this time is up to 6 months. Make the foundation in the fall, build the walls in the spring. But, if the customer is in a hurry, and this is not important to him, then you can do without waiting for shrinkage.

2.5. Thermal conductivity

The calculation of thermal insulation characteristics is regulated by the following documents:

— SNiP 02/23/2003 “Thermal protection of buildings”,

— SNiP 23-01-99 “Building climatology”,

— STO 00044807-001-2006 “Thermal protection properties of building envelopes”,

— SNiP II-3-79 “Construction heating engineering”,

— SP 23-101-2000 “Design of thermal protection of buildings.”

Table 15. Thermal insulation characteristics of wall and roof sandwich panels.

Table 16. Minimum thickness of wall and roof sandwich panels in regional and regional centers of Russia by building groups.