Dry construction

Dry construction is a term used to describe a specialised method of interior construction, i.e. interior design, based on the use of industrially prefabricated construction systems. Such systems comprise of two basic construction elements – load bearing construction and lining, which, when put together, form a static, functional and aesthetic unit. Dry construction has become synonymous with quick, safe and quality construction of interior and exterior elements. Quality performance and quick and dry assembly, which does not require any additional time for drying of the construction, are important factors in this day and time, characterised by an increased pace of living and working. Gypsum is used as one of the basic materials in dry-assembly works.

What is gypsum?

Gypsum is a mineral-based natural material which is compatible with human skin due to its pH value and heat conductivity. It does not contain any toxic or other substances harmful to the human health, which is substantiated by the fact that gypsum is widely used for medicinal purposes (e.g. it is used in casts for immobilization of fractures, where it comes in direct contact with the skin) and in stomatology. Some other important features of gypsum are its porous structure, which makes it a good insulator, and its capability to absorb or release moisture, depending on the humidity in the space. These properties make it an ideal material for the interior space construction, while it makes the already built spaces comfortable to stay in due to the natural moisture regulation which does not require any energy, thus ensuring an ideal microclimate for humans.

Gypsum and construction

Gypsum is a material which, by its chemical composition, is calcium-sulfate (CaSO4×nH2O, where “n” is the number of bound water molecules and, depending on that number, it can receive up to 20% water). It was created by sedimentation during the water evaporation in shallow sea coves in the period from 100 to 200 million years ago. Today, gypsum as a raw material is obtained from underground mines or surface mines. And in view of the hardness of the gypsum, it is placed in the second position on the Mohs scale of mineral hardness, which makes it one of the softest minerals, and therefore one of the most workable minerals. Due to these characteristics, gypsum was used as a construction material as early as 11000 years ago in ancient Jericho, where it was used for the construction of walls and ceilings. Ancient Egyptians used it for the construction and decoration of the pyramids, while it had a revival during the baroque period, due to its ability to be cast, and was used as a material for building complex ornaments and decorations with perfect lines, which we still admire today. Presently, gypsum is most commonly used as a material in the form of panels, with both sides covered by cardboard for increased strength, which is then fitted onto the load bearing construction.

Gypsum boards

They are made of gypsum plaster whose surfaces and longitudinal edges are firmly wrapped with highly adhesive special cardboard. Gypsum boards are manufactured in lengths ranging from 1500 mm to 3000 mm and widths ranging from 600 mm to 1250 mm, with various types of edges. Their thickness ranges from 9.5 mm to 25 mm. They are relatively light, highly elastic, can be bent and are easily worked with, cut and fitted. They are non-flammable and, when combined with adapted wood or metal substructure and with adequate insulation materials, they form inner wall and ceiling systems, which meet all requirements with regard to loads, heat, sound and fire protection. Gypsum boards are used in new buildings and for renovations as wall and ceiling casings fixed to the substructure or glued directly to the substrate as partition walls and dry flooring.

Types of gypsum boards:

• Standard panels
• Fire protection panels
• Moisture resistant panels
• Panels with lined surface (e.g. steel sheeting or plastic)
• Panels with lined back side (e.g. aluminium foil (barrier to passage of vapour)
• Dissipative foil (against electrical fields and high frequency radiation)
• Panels with perforated surface or surface with slits (sound absorbing)
• Multilayered panels with integrated thermal insulation layer

Other special purpose panels:

• Cement panels (for exterior use or use in “aggressive” environments; e.g.chlorinated indoor swimming pools)
• Baryte panels (for protection against radioactive radiation)
• Kevlar panels (for protection against firearms or other types of piercing)

Dry construction systems with gypsum boards

FLOORING SYSTEMS – Dry Screed

Dry screed is a flooring system made from special gypsum fibreboards made for that purpose. It is assembled by laying panels on a substrate made from fine granules which serve for levelling the substrate and as a heat and shock sound insulator. Panels are laid with mutual overlaying and interconnecting, thus forming a whole. Joints are filled with gypsum-based mass, thus making the surface of the screed uniformly smooth and straight. Identical systems have been developed for uses in wet areas, but with cement-based panels in order to avoid swelling of the gypsum.

Advantages of this type of screed in regards to the classic glazing are as follows:

• Increased system strength – no ruptures or expensive repair work on cracks with epoxy resins
• More accurate fabrication – panels are level, there are no “peaks and troughs” on the surface of the glazing and therefore no need for sanding or levelling
• Speed – dry screed can be laid much more quickly than classic glazing, and finishing linings may be glued the next day, while the glazing must be left to dry until an acceptable level of moisture is reached, thus allowing the laying of the finishing floor linings. Due to the glazing composition and weather conditions, glazing often cannot dry naturally and must be dried by specialised equipment, which is quite expensive to rent. Also, the expenditure of electrical energy is not negligible. During the colder days, glazing even needs to be heated in order to evaporate the moisture, which causes the heating costs to multiply
• Smooth surface – unlike with classic glazing, the surface is smooth and does not need to be levelled by floor levelling compounds prior to the gluing of the thin floor linings
• Lighter construction – less weight per unit of surface area enables it to be used in statically limited structures (e.g. structures with wooden interfloor structure etc.) and, due to its inclusion in the calculations of static load for new buildings, it enables simpler and less expensive dimensioning of the structural elements of the object
• Simple fitting of the installations underneath the floor surface

GYPSUM BOARD WALL LININGS

One of the basic and most common elements in dry construction are gypsum board wall linings, which have numerous advantages over any other system. Gypsum boards wall linings are far lighter than any other structure, which enables use in facilities with weak static conditions. The use of different systems depending on the client requirements and regulations, considerably better properties can be achieved when compared to other wall solutions and at a lower cost. Considering the multi-layer construction of the wall itself, it is possible to achieve completely different properties on the opposite sides of the wall, in line with the requirements and intended purpose of the spaces on both sides. By using different constructions, it is possible to achieve a high degree of heat and sound insulation, fire protection, moisture resistance, and, by using special panels and other layers in construction, if necessary, other properties, such as protection from harmful radiation, intrusion protection, protection from firearms and fragmentation of explosive devices, as well as various other special properties, can be achieved. Modern systems even offer the possibility to install heating or cooling elements, which enables the wall to function as radiators or air conditioning devices and they can even play music after the installation of special oscillation modules and connecting them to the home audio systems. Considering all of the above mentioned, we can see how wide the possibilities in building gypsum board walls truly are and we can boldly claim that there is a system for every requirement.
Furthermore great advantages of gypsum board walls when compared to classical wall constructions, are as follows:

• Quick construction – in comparison to classic walls, there are almost no technological halts in construction, they can be immediately built to full height, walls do not need to be mortised, rendered and plastered, construct horizontal and vertical ring beams etc.
• Increased precision – special laser devices are used for placing of the construction during the process, i.e. the assembly, which achieve almost perfect vertical and horizontal orientation of the walls.
• Smooth and straight surfaces – gypsum boards used for wall assembly are smooth and straight. After the trowel finishing of the wall, final works can be carried out the very next day, regardless of whether this includes painting, tiling, wallpapering or placing of any other wall lining.
• Quick placement – installation – routing installations through gypsum board walls is exceptionally quick and simple and there is no need for mortising since the installations are routed during the wall’s assembly through the interspaces between two linings. Subsequent routing of installations is greatly facilitated since the wall is only partially opened and its repair is much quicker and simpler.
• Possibility of creation of various details, shapes, decorative elements, curved walls in both horizontal and vertical direction.
• Works are carried out dry and with minimal waste, and can be performed in already finished spaces, with only minimal dust protection of the surrounding area.
• Healthier microclimate for human habitation – natural regulation of humidity in the air, without releasing any odours, unlike cement-based materials

DROPPED CEILINGS FROM GYPSUM BOARDS

Except for the partitions, gypsum boards are used in the construction of dropped ceilings, which are built, if required, from standard, watertight or fire resistant boards. Ceilings are usually dropped to hide installations and to install lighting and create special light effects in the room. Attractive design possibilities are virtually unlimited, the same as in the case of gypsum board walls. Except in the form itself, the possibilities of different solutions are evident in the vertical play, i.e. cascading ceilings and creation of different levels of dropped ceilings, accompanied by the installation of lighting elements. One of the important features of dropped ceilings is that they retain a layer of air in the interstice, which serves as thermal insulation between two floors or towards the exterior areas. The construction of dropped ceilings with perforated GK panels significantly reduces the echo in the room, and individual manufacturers have developed the manufacture technology to the point where they are able to manufacture perforated panels in accordance with the specifications given by the client, and deliver them already painted in three coats, ready for installation.

OTHER DRY – PREFABRICATED SYSTEMS

RAISED FLOORINGS

Raised floorings are modular floors assembled by placing panels on metal legs. Due to the great variability in the leg height, the necessary flooring and structure height can be achieved with modular panels which can be subsequently opened. They represent a sort of a revolution in the flooring construction. Such systems enable the routing of a large number of services underneath the floor, as well as subsequent modifications on said services. Due to these features, they are especially suitable for office spaces with many desks and electrical and networking installations, since all installations must be routed to each workplace underneath the floor surface. Due to this, they are commonly known as raised access computer floors. If such floor is combined with some sort of modular finish lining (e.g. carpet in panels), all subsequent modifications to the installations, which are made when offices are rearranged, require only minimal investments to route all the necessary services to the desired location. As an alternative variant, there are modular floors made from calcium-sulphate panels. They are glued to each other to form a strong, interconnected unit with a smooth and straight surface ready for laying any final lining, taking into account that floor panels are mounted on special metal legs, thus forming an elevated floor structure that also enables passage of different installations underneath the floor surface. They are exceptionally suitable for installation in kitchens, toilets and bathrooms.

MODULAR CEILINGS

There are currently many different systems of dropped ceilings which can also meet any requirement made by the client. The advantage of using such ceilings in office spaces is their capacity to be opened, which simplifies the maintenance and control of all installations located in the ceiling, as well as possible new installations. There are different systems with linings made from gypsum, wood or metal , but ceiling systems with mineral fibre panels proved to be the best choice lately. These ceilings can aesthetically meet the same requirements as metal or wood ceilings at a much lower cost, but, depending on the needs, they can also meet other requirements concerning heat or sound insulation, sound absorption or reflection, fire resistance, as well as all other demanded requirements.

STRETCH CEILING

Stretch ceilings are constructed with foils produced specially for that purpose. The surface may be painted with different high gloss or matte colours, and there are also transparent foils above which lighting can be placed for illuminating the entire ceiling surface. Ceiling is constructed in a way that a foil of designated dimensions is stretched over the structure mounted along the edge of the ceiling. Other lighting bodies can also be installed, as well as sprinkler jets and all other necessary equipment. Wall linings can also be constructed from the same material, and regardless of whether the foils are mounted on the ceiling or on the wall, any motive of the client’s choice can be printed on them additonally.

LAMELLAR CEILINGS

Lamellar ceilings are most often mounted on a substructure of steel profiles, “combs”, to which lamellas are attached. Lamellas are most commonly made from sheet aluminium and can differ in shapes and forms. Depending on the construction of “combs” and lamellas, the ceiling surface can be open or closed.