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Not everyone has the desire and opportunity to delay construction for several years. Moreover, there is no need for a long time. There are several technologies for rapid construction. The leaders are frames. With a minimum of costs, we very quickly get a full-fledged building. But the frame is only half the battle. We still need to choose a cover. One option is multi-layer materials. They are called sandwich panels. The dimensions of the sandwich panels make it possible to further reduce the construction time, because we immediately get a building with an exterior, and sometimes with an interior finish.
What is a sandwich panel
Sandwich panels are a modular building material designed for cladding buildings and structures that are built using frame technology. They consist of three layers: two sheets of hard material and insulation between them. The use of this material significantly speeds up the finishing and erection of buildings, since both the outer cladding, the insulation, and the inner cladding are immediately mounted. And yet, the dimensions of the sandwich panels allow you to cover the roof of a fairly large house without horizontal seams – the maximum length of the sandwich panel can be 12 meters. More than enough for a gable roof. The only question is transportation, but that’s another story.
So, the design is three-layer. The layers are glued together and simultaneously pressed. There are two ways of pressing – cold and hot. In any case, the layers are held securely. It is impossible to tear them apart without the use of mechanisms.
By appointment, there are sandwich panels for wall and roofing. They usually differ in appearance, the thickness of the materials used and the type of profile. There are smooth plates, there are with different types of profiles. Roofing is corrugated like a profiled sheet, and there are very similar to metal tiles.
There are also special purpose options. For example, for garage doors. Usually these are steel sheets, but coated with pural or some other damage-resistant polymer. They differ in the shape of the castle. Such gates are usually made lifting, so that the locks have a different shape. And the longitudinal edges are not open, but closed with the same steel sheet, which is bent, forming a smooth bevel.
Wall sandwich panels can be smooth and corrugated. It is traditional (wave, trapezoid, fine corrugation), and there is a more decorative one – under stone, brickwork and even wood.
In general, the appearance of sandwich panels can be different.
Of what do
The materials of the outer layers of sandwich panels can be different. The most common with a “shell” of sheet steel, but there are also aluzinc, drywall, plastisol, polyester, pural, DSP, OSB (OSB), chipboard. The choice of material depends on the purpose of the building that is going to be finished, and on the installation site. The dimensions of the sandwich panels do not depend on the materials of the layers, so there are no restrictions.
For example, during the construction of warehouse and industrial, utility rooms, both sides are steel sheets. The coating and profile of the inner and outer sheets can be different for the required tasks. When sheathing the outer walls of private houses, there can be metal on the outside, and inside GVL, GKL, chipboard, OSB. Depending on what the owner has chosen. For partitions, there are options on both sides with fiberboard, gypsum board, OSB and chipboard, or combinations thereof. The material is good because there are different options both in terms of characteristics, appearance and price.
Outer layer – steel sheets
Sheet metal is used as the outer layer of sandwich panels. Sheet thickness – 0,35-0,7 mm. If the metal is placed on both sides, then for the outer one they take a thicker one – 0,7 mm, for the inner one – a thinner one – 0,35-0,5 mm. Agree, it’s justified. Firstly, the weight is less, and secondly, the cost is lower. And the strength for the inner lining is more than sufficient. Even if it’s a production facility.
The metal is covered with several shells with protective properties. Galvanizing is required, and then additional layers are applied – primers and polymer coatings that protect and give a more “civilian” look.
Types of polymer coatings for sandwich panels
The quality of steel is very important, but galvanizing and the quality of protective coatings are no less important. The durability of the metal, and hence the reliability and durability of the wall or roof, depends on how carefully the coating is applied. First, the steel sheet is coated with zinc, and then one of the types of polymers is already applied to the galvanized surface. It could be:
- Polyester – SP or PE. Inexpensive, resistant to ultraviolet, corrosion, temperature extremes, does not fade for a long time. Applied with a thickness of 25 microns. The disadvantage is the low resistance to mechanical damage. You can even scratch it with a nail.
Businesses are trying to make the protective coating as reliable as possible. - Polyvinylidene fluoride (PVDF, PVDF). Very high resistance to fading and high temperatures, chemically aggressive environments. Coating thickness 20-25 microns.
- Polyurethane. It is applied with a layer of 35-55 microns. Requires a good primer. Does not fade, tolerates temperature changes. Good for roofing materials.
- Polyvinyl chloride (PVC or PVC). It is applied in the thickest layer – up to 200 microns. It has the highest resistance to mechanical stress. It makes sense to apply for wall panels. But it does not tolerate high temperatures. The maximum continuous heating is not higher than 60°C. It is better to use in the Middle Strip and in the North.
Colors can be very different. Most coatings allow you to choose any color from RAL tables - FARM. It tolerates chemical environments well, resistant to corrosion, ammonia and fertilizers. It is used in poultry houses and premises for livestock, granaries. It can only be applied on galvanized surfaces, with a zinc layer of at least 275 g/m².
- Sanitary coating CLEAN (Food Safe). It is safe for food contact. Does not react to salt, acid, alkali and solvents. This coating is used in buildings related to the food industry, medicine, pharmaceuticals, electronics.
Of this list, polyester, PVC and polyurethane are most often used. Sandwich panels are also made from stainless steel sheet. Such sandwich panels are used in refrigerating chambers at enterprises of the food or pharmaceutical groups.
Sandwich panel profiles
Sandwich panels with metal outer cladding can be smooth and profiled. Smooth ones have a lower mechanical resistance; it is easier to make dents on a flat surface than on a corrugated one. If the house is in the yard, the probability of damage is small. Moreover, the paths can be made not close to the walls of the house, but to make a soft blind area and plant a flower garden or sow a lawn on top.
You can also take profiled sandwich panels for cladding the frame. Some look exactly like lining, but there are more interesting options. True, and for the price they are “more interesting.”
Heater
Insulation for sandwich panels is also used differently:
- mineral wool (stone or glass);
- polyurethane foam (foam or PPS);
- expanded polystyrene (PPU or PUR);
- polyisocyanurate foam (PIR).
The best of all – the last – PIR. He appeared quite recently. Thermal characteristics are on par with PPU, but better in terms of fire safety (tolerates heating up to 140 ° C without destruction and ignition). Its disadvantage is the high price. In general, they usually choose between mineral wool and polyurethane foam. Styrofoam loses to both of them, although it costs less. But the difference in price does not cover the difference in performance.
Sandwich panel dimensions
There are no standards for this type of building material, so if you wish, you can find or order those sizes of sandwich panels that suit you best. Many manufacturers are doing this. It is not a fact that a large enterprise will make a small batch according to your requests, but you can negotiate with small ones. Although, you can talk with the big ones.
Most likely, “custom” sizes of sandwich panels will be more expensive (in terms of square meter). But it can be justified. Less cuts/waste, lower overall costs. In general, it is necessary to consider and look. In general, each company has its own maximum and minimum dimensions. They depend on the available equipment. The table summarized the most common sizes of sandwich panels. They were divided according to their purpose – wall and roofing. Because they are usually different.
| Length | Usable or working width | Thickness | |
|---|---|---|---|
| Wall | from 2000 mm up to 12 000- 14 000 mm | 1000 mm 1150 mm 1190 mm | from 30 mm to 250 mm |
| Roofing | from 2000 mm to 16 000 mm | 1000 mm 1150 mm | from 50 mm to 220 mm |
Please note that the “working” or “useful” width is indicated. In fact, the size of each panel will be slightly larger – just due to the lock. When calculating the quantity, you will need exactly the working width. And the actual one will be required for transportation, but rarely anyone indicates it. You can check with sellers. And on average, you can throw on 15 cm. This is more than enough.
One more moment. Not all manufacturers have all the sizes of sandwich panels indicated in the table. These are “collective” results. The most frequently encountered values are selected. But one company offers only one width, another – two or all three options. Similarly, not everyone can make a sheet 12 meters long. Someone has a maximum of 6,3 meters. So again, monitor the situation in your region.
Features
As you understand, it is difficult to talk about the characteristics of sandwich panels “in general”. Too different materials can be used. And “sheathing”, and insulation, and the thickness of all layers. All this is different. And the characteristics of each of the components vary over a wide range. Therefore, specific properties should be looked at already when they have decided on the manufacturer. In the meantime, so that you can orient yourself, we will give the data of one of them. By the way, you can see the tables in the paragraph about the types of heaters. This is from one of the sites. In this section, we present data from another manufacturer. At the same time, you can evaluate the range of values.
If you compare the two tables, you will see that in the first case, a sandwich with expanded polystyrene has a higher thermal resistance. In the second, on the contrary, basalt wool turned out to be more “warm”. And no one is lying about it. They just use different materials. That’s all.
The bearing capacity may also be of interest. Here the situation is approximately the same as with thermal resistance. Depends on the metal, the presence or absence of relief, its shape and size. The insulation and the method of connecting the layers also contribute. In general, there are also many criteria. So, the values must be recognized for a specific material. And we give the table for reference only, so that you can roughly estimate the possible load.
As you can see, quite a decent bearing capacity. This makes it possible to make not only walls and roofs from sandwich panels, but also ceilings. Not a bad way to speed up construction.
Connecting sandwich panels to each other
Sandwich panels are interconnected with locks. Wall and roof locks differ, and significantly. In roofing, on the one hand, the release of steel in the form of a wave is specially made. He “puts on” the ledge of the previous sheet. This is how the connection happens. In the wall panels, the lock is made according to the tenon-groove principle. Moreover, it is better if, according to this principle, not only the outer skin is connected, but also the insulation.
In general, in the whole structure, it is the panel joints that are the weakest points. Not only in terms of safety, but also in terms of keeping warm. The first panels were with the connection of only metal sheets, and the heaters were simply joined. But the seams froze through, so they began to complicate the shape, creating labyrinths. Also, when connecting, additional sealing tapes are used to definitely avoid blowing and freezing.
In some cases, additional fixation is used – self-tapping screws or studs. Some forms of locks allow the fastener to be hidden, in others it is installed from above. By the type of installation of profiled sheets and metal tiles.