Natural stone in the exterior finishing of buildings
Advantages of natural stone
One of the main advantages of natural stone, used for the facing of facades, "the durability of the coating. The best proof of this is the hundreds and thousands of buildings around the world, faced with natural stone and have not changed their appearance in the course of centuries.
Another, not less important than the quality of natural stone – its beauty. It is difficult to name another finishing material, where would such a harmonious severity and elegant grandeur and elegance. The city, the buildings in which are faced with natural stone, has its unique "person ". For example, those who have seen the morning Yerevan, will always remember the pink light, which literally radiate walls, marble, tuff. And how can we forget granite outfit Petersburg or Berlin, which gives the city a truly royal majesty!
However, natural stone is not only used in the finishing of the buildings in the city, embankments and bridges. Not less important sphere of its application is private construction. In this case, the natural stone is not just in the role of finishing material, and as a symbol of well-being, prosperity, robustness, and reliability. Private houses, in the internal and external decoration which used natural stone, with each passing year becomes more and more. And this is not surprising. After all, with the observance of technology of laying the stone tiling will last almost forever.
Those who had a chance to visit in Amsterdam, you may have noticed that the inhabitants of this city is extremely value their history. Love in the old days appears here in all. Including the protection of monuments of architecture. For example, if the building has kept the interior or the lining of at least a hundred years ago, the maintenance of the city treasury allocates the owner of special loans. There are even companies that make wiring, plumbing, furniture and door handles, in accuracy repeating those that were produced one hundred and more years ago. In one of these amazing houses were architectural elements, the age of which exceeded the age of the house! It turns out that in the 19TH century masters had to demolish the old building, it was built in the XIII century, because to him it was impossible. But the granite steps of the porch and the lining of the cap, as well as internal staircase of bog oak moved into a new house. They decorate it so far!!!
Cons of natural stone
Most of the shortcomings of natural stone rather fetched than real. But even around the obvious facts sometimes formed so many conjectures that impartially in order to understand what are the disadvantages of natural stone and the extent to which they are essential, it is quite difficult.
The main objective lack of natural stone is considered to be its weight. Indeed, stone and really is one of the most difficult of finishing materials, and this factor must be taken into account. But this does not mean that the stone should be refused only on the grounds that he was too weighs a lot. Just in each specific case it is necessary to provide individual calculations, proceeding from the height of the buildings, rock stone, thickness of facing plates, the total weight of the panels, to take into account the way of fastening, the thickness and material of the walls and many other factors. Such calculations are very complex, but necessary to create not only beautiful, but first of all a safe and durable buildings.
Radioactivity. In recent decades has become widely spread радиофобия – fear of radiation. How real fears related to the radioactivity of natural stone, is a topic for a separate article. Here we will mention the following.
Firstly, the increased radioactivity have not all rock stone, but only magmatic (granite, diorite, gabbro). Even a stone from one field, but from different strata may by order vary on the radioactive background. As such species as marble and dolomite, generally relate to the other group, so they unnecessary x-rays are not threatened. Secondly, there are sanitary-and-hygienic norms, according to which each batch of stone, you can use either indefinitely, or with restrictions (for example, "only for outdoor use"). This should be borne in mind and not spread stone for the exterior works worktop in the kitchen or the floor in the bedroom. Thirdly, offer a stone, not corresponding to the norms of radiation safety and not having for this reason, the necessary certificates, will not do any self-respecting the supplier.
The use of stone in the exterior
Qualified to work with natural stone could not every designer and architect. And this is very important. Because of the construction and finishing of the building invested large funds, and the customer should be sure that they will be spent wisely.
Ideally, the facade should be designed in a complex with all of the building. In this case you can still on paper not only to calculate the cost of works and the most effectively plan the use of materials, ways of their combination and methods of installation. This, of course, does not mean that it cannot be finished with natural stone already completed building. Just in this case the architect will be considerably less freedom – design features of finished house dictate certain restrictions as the choice of materials, and ways to use them.
Experienced architects and designers are able to "fit" and the house itself, and his finishing "under the master", taking into account his character, tastes, habits (if it is a private house), or under the concept of the building (if it is under construction shop, office, entertainment complex, etc.). For example, a dark stone (gabbro, labradorite, dark granite and marble) symbolizes the thoroughness and monumentality, and in some cases – isolation and inaccessibility. Bright as granite, marble and limestone rocks are associated with ease, openness, festive.
Not less important role in the creation of the appearance of the building plays a way of processing the surface of the stone. Traditionally for decoration of private houses use of polished stone, which looks effectively in small areas. Monumental buildings best stoning polished or brushed stone. In the finishing of the ground elements often processing is applied to the "wild "stone imitating the texture of the rocks. As a rule, the"wild"stone (granite, dolomite and limestone) adorns the base of large buildings, emphasizing their monumentality and thoroughness. A striking example of this finishing serve stalin’s skyscrapers" – the house on Kotelnicheskaya embankment, the hotel "Ukraine", the building of the moscow state university. Very elegant looks a combination of "wild" and бучардованного stone.
"Wild" stone looks great and in the decoration of private houses. Here is just one example. In Saxony there are house, perched on the slope of a steep hill, covered with beech forest. The designer planned the lining so that I get the impression that the house grows out of the rock. To create this effect, the foundation of the shit out of "wild" granite and facing practically merged with the slope of the hill. Wide granite blocks of the foundation of the house-rock narrow at the top and gradually transformed into the wall, lined with light limestone. Adjustment of the stone slabs was so accurate, and the cracks in the masonry so well concealed that even in the vicinity of the house is not the feeling that the building of the "embedded" in the granite rock.
Application of various types of stone from the point of view of their physical properties. Compatibility of rocks
Let’s consider a hypothetical house, which is expected to be revet natural stone. It’s worth to start with, of course, reasons. For socle facing is necessary dense, frost-resistant stone, it is desirable to dark tones. Because of the lower part of the walls are the most vulnerable to the impact of adverse factors: temperature changes, contact with water and mud, etc. And basement cladding must be capable of withstanding the impacts for tens or hundreds of years. On the properties for this I the role of the most suitable breed of a magmatic origin – granite, labradorite, gabbro and related them, as well as quartzite, sandstone dark coloration. Marble lining of the socket to use generally not worth it, the more light – literally within a few years he will lose the "commodity" view. Also it is undesirable to apply for the decoration of the cap loose sedimentary rock is limestone, dolomite, coquina. Most of these breeds has bright colors, it is clearly visible bruises from the rain and mud. When facing the cap particular attention should be paid to the sealing of the masonry joints (especially the bottom, at the base of the wall). If in these joints will enter the water, this may adversely affect the strength of the coating. The thickness of the ground plates, their size and texture of the surface can be very different – here all depends on the choice of the designer. The only requirement of building codes, relating to the texture of the stone, due to the thickness of the slab. Plates, processed бучардой, with the sawn surface and texture of "wild stone" thicker and heavier than the usual polished slabs, therefore, they should be placed only on the solution, filling after laying seams sealant.
Selection of a stone for facing of walls in the first place is dictated by considerations of design. But a few general points are there. According to requirements of building norms, facing slabs area of up to 0.4 m2 and up to 10 mm thickness can be placed on the glue without additional fastening. But the elements of large overall dimensions require in addition to the solution of the additional fastening to the wall. For "wet" stacking there are restrictions on the height of the building. However, certain standards in this respect there, and for each project, this indicator is calculated separately. We only note that, as a rule, such limitations relate to multi-storey buildings (5 or more floors).
Regard to the selection of a stone for facing of walls, there restrictions are much less than in respect of the cap. For finishing of walls of a building is fit and limestone, and dolomite, and many other "soft" breed because the walls of the building are less exposed to harmful influences and erosion. However, for the sake of justice, I must say that the stains on the surface of a light-colored stones may appear all the same. Especially in those cases where, for example, balconies, bay windows or other speakers architectural details were not equipped with the right gutters (i.e. do not have водоотбойных canopies). In such cases, the rain water flows down on him to the wall, and not vice versa, as it should.
The main and, it seems, the only serious limitation in the selection of facing stone is the incompatibility of silicate rocks (quartzite, sandstone) with carbonate (marble, limestone, shell rock, dolomite, limestone). In Their direct vicinity of the information contained in silicates silicic acid reacts with calcium carbonate (the basis of lime rocks), and both stones disintegrate rapidly. Other breeds can"touch" with each other without much damage. But you have to remember that stones at facing of walls necessarily placed with a gap, as they have the feature to increase or decrease the volume when you change the temperature, and every breed these indicators are unique. The gaps depends on the size of the plates, on the density of stone and is calculated in each case separately. If the walls revet, for example, not one, but two breeds, the gaps should be calculated for the one in which the coefficient of volume expansion more.
Types of fastening of facing elements
There are two basic types of fastening stone cladding of the walls and the ground floor: with the help of adhesive mastics and mixtures (the so-called wet method) and glueless method – through a variety of fixing systems. It is also found and intermediate option, when the plate is fastened to the wall mechanically, and then pour the space between the wall and the facing of the solution. When this plate is often perpetuate not only in the wall, but also with each other.
When using the adhesive method is desirable to use a special mastic. They provide elasticity connection, neutralizing the effects of temperature changes, and the protection of the stone from the condensate, arising as a result of the circulation of water vapor from the interior through the wall outside. However, for complete protection from the formation of water vapor one of mastic is not enough – the walls of the building should have an internal vapor barrier. This rule is true for the mixed type of attachment.
In the "wet" method of mounting plates external finishing work should be planned for the period from may to October. In another time, almost on the whole territory of Russia dominates the low air temperature, as a result of which the water contained in the solutions and mixtures, can freeze and thus degrade the properties of the adhesive.
Universal solution. As practice shows, universal solutions, which again would be solving all the problems do not happen. However, the facade is a lucky exception from the rule. In this kind of work there is a method that allows neutralize or minimize harmful impacts on the facing and to ensure that the facing elements have served as long as possible. It is loose fasteners, which is used in the device of ventilated (hinged) facades. General principles of the equipment of hinged facades are simple: decorative elements with the help of anchors fixed in the walls of the building, leaving a gap between the stove and the wall from 30 up to 250 mm (depending on the size of the plates, use of the thermal insulation, etc.). Between the plates leave gaps for the compensation of thermal expansion. In these joints is possible to put the elastic gasket or seal them sealants. In addition to anchor fasteners in recent years increasingly used fasteners for modular lattice, suspended tyre and other similar systems.
So, what are the advantages of hinged way of wrapping?
1. Neutralizes the harmful effects of temperature and moisture (rain and condensate). The constant circulation of air between the wall of the building and facing provides an output of water vapor out and prevents condensation of moisture.
2. There is no need to prepare a wall laying the adhesive or mortar, as the existence of irregularities, the wall does not play any role, as well as presence/absence of plaster. Moreover, with the help of hinged the facade, you can hide the external defects of the main wall.
3. Removed the limit on the height of buildings. Each element of the cladding provides load only the "a "portion of the wall, in no way affecting the lower ranks, as this occurs when the adhesive mounting. In view of this, it becomes possible to use plates of large sizes (up to 2-3 m2) and a large thickness (up to 160 mm), which significantly reduces the cost of the lining. In addition, there is no need for expensive mastics and glue compounds.
4. Significantly expands the capabilities of design: "independence" of each tile allows the use of breed, different by their physical characteristics, in a variety of combinations.
There is another, very promising way of hinged panels with the use of sandwich-panels made of natural stone. Such a panel is a tile thickness of not more than 7 mm, fixed on сетчатом алюмопластиковом frame, which performs the role of the valve. One square meter of such tiles of granite weighs usually not more than 16 kg (for comparison: plain неармированная granite panel weighs from 35 to 60 kg/m2, depending on the thickness). The advantages of the new material are obvious: reduced consumption of stone, a significant decrease in the total weight of the structure and loads on the wall.
Combating erosion and pollution. Protective compounds
Of course, fully protect the stone facing of external influences is impossible. But that she had served for more than a century, its cleaning from the inevitable pollution was light, and do not turn into a restoration work, many manufacturers have developed a number of special preparations. Their application allows to protect the stone facing of the majority of adverse effects. As a rule, these compounds are of general protective function (for example, water and dirt resistant) or have certain characteristics (protection from acids, alkalis, organic solvents and paints, microorganisms, etc.).
Water- and soil-repellent compositions especially recommended to handle the loose rock stone, easily absorbing the moisture (sandstone, coquina). These drugs provide protection from rain, splashing mud and water-soluble salts and paints.
Маслогидрофобные compounds are suitable for almost any type of stone and, in addition to the water-repellent properties protect the surface from oil products. Such impregnation is particularly necessary for the protection of facades, facing on the main streets with intensive traffic flow.
Impregnation, resistant to acid environment, are indispensable in the regions, where not a rarity – acid rain. After processing the impregnation of the building, finished dolomite or shell rock, coating will be in safety.
There are impregnation of bactericidal properties that protect the surface from her appearance on mosses, lichens, and microorganisms. This is especially true for the cladding of the calcareous rocks, which is in high humidity conditions.
And, finally, there are preparations for struggle with lovers of the wall-paintings. Remove from the unprotected surface of natural stone spray paint, which is used by the authors of the graffiti, it is quite difficult. But if the stone is processed by a special protective impregnation, this operation will have no difficulty.
But it’s all preventive measures. And how to be in those cases, when the walls have already suffered from erosion, mud or were covered in graffiti? There are compositions and methods for practically completely removed from the surface of the stone most of the pollution. Even with such "difficult" to clean the tiles, as limestone or dolomite.
In the end?
The combination of various types of stone and ways of their processing provides architects and designers practically unlimited possibilities to create original solutions for the construction. But working with it is not a simple matter and a very individual. In addition to taste it requires the designer great experience and excellent knowledge of the properties of the material. In addition, you need to remember that the stone is different not only from other finishing materials – even its various breeds may be completely incompatible with each other with the physical and chemical point of view, not to mention the design. A specialist is required technically competently work with stone, considering the mass of the nuances and details. Only in this case, natural stone fully justify the title of the most elegant and durable material.
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