Dome houses – construction technology

Recommendation points

• A little about the history of origin
• Design features
• The basis for building a house
• Construction of buildings based on a geodetic sphere
• Dome construction based on pneumo-frame
• Dome houses on the basis of fixed formwork and factory buildings
• Installation of floors and partitions
• Features and benefits of domed houses
• Energy saving features
• Unrivaled strength characteristics
• Maximum savings
• Optimum distribution of space and unrivaled comfort

In the article we will talk about the technology of domed construction, about the features and advantages of domed houses, about the three most famous methods of erecting such buildings. But most importantly, we will introduce you to the calculation of economic costs, the result of which gave domed houses an undeniable advantage..

The use of dome construction technology can cut the cost of building materials by half and cut the construction time by three times. The solution to the problem rests only on the technical re-equipment of construction sites, because all the necessary materials have already been used in construction for so long. This technology has been successfully used in the USA and Western Europe since the end of the 20th century. Fortunately, now a good and solid foundation has been laid in the post-Soviet space for the development of domed housing construction..

A little about the history of origin

You should start acquaintance with domed houses by studying the history of their origin. Since ancient times, man has known for certain the essence of harmony with the surrounding world, partly expressed in the form of buildings. An example of this is the multiple prototypes of ancient dwellings created in the form of a hemisphere: igloos of Eskimos, wigwams of North American Indians, tents of African tribes. It is also common for many cults and religious denominations to use domes as elements or bases for temples, cathedrals and chapels..

In the modern world, dome construction technology dates back to the first half of the twentieth century, when the American engineer Richard Fuller patented a construction technology that could provide post-war Europe with affordable housing. Unfortunately, the idea did not spread, but after fifty years they started talking about domed houses again, and this time – in earnest..

Initially, the inhabitants became interested in the idea of ​​houses in the form of a hemisphere only due to their original shape. A little later, people realized the indisputable advantages of such structures and their number in the modern world is constantly growing..

Design features

Due to the special shape, the domed buildings can be safely classified as works of art. They look quite miniature, but this image is deceiving: despite the external compactness, these houses are very spacious. One may get the impression of fragility and unreliability of the design, but an attractive appearance in this case does not at all imply the presence of technical flaws. Dome houses are superior in all respects to conventional cube-type buildings.

The basis for building a house

The very essence of domed housing construction implies the absence of ceilings and supporting supports. This gives not only up to 30% savings on wall and floor materials: the structure becomes lightweight and does not require a massive base.

The obvious savings from the construction of a domed house are visible already at the first stage of construction – in the process of building the foundation. The lightweight foundation saves 50% of the money spent on the production of earth and concrete works. A strip or pile foundation is usually used as a basis..

Construction of buildings based on a geodetic sphere

The first known method for the implementation of domed buildings was a technology based on a frame in the form of a triangular hemisphere. The method is based on the use of triangular blocks of equal size, which, with increasing height, tilt their tops towards the center more and more, thus forming a dome. When connected, the blocks form a frame, up to forty centimeters thick.

Outside, the house is finished with pressed cellulose impregnated with bitumen, metal cladding or simply plastered. The main requirement for exterior materials is absolute water resistance. From the inside, the walls are sewn up with boards, and medium density mineral wool is used as insulation. The problem of natural light in the house is solved by triangular double-glazed windows in a plastic frame, made according to the dimensions of a standard frame cell. If the glass unit is enclosed in a reinforced metal frame, adjacent cells of the frame can be combined to achieve a non-standard geometric shape of the window.

The peculiarity of this method is that the buildings are made of environmentally friendly materials. The geodesic dome is today used as a basis in exhibition pavilions, greenhouses and sports complexes.

Dome construction based on pneumo-frame

Another construction method became available relatively recently, and owes its appearance to the rapid development of polymer materials. This technology is the most unusual and complex, but it is thanks to it that the time for building a house can be reduced to a minimum. The question of the applicability of this method directly depends on the availability of specialized equipment in the construction area: installations for spraying concrete mixtures and equipment for installing pneumatic frames.

The basis of the house, as always, is a light strip foundation in the form of a ring or a solid monolithic slab. Along the perimeter of the foundation with an indent from the outer edge of 20 cm, “tails” of vertical reinforcement elements are displayed. The rods should protrude at least 40 cm, and the distance between them is from 30 to 50 cm, depending on the size of the structure and the diameter of the rods. The reinforcement must be used in profile, with a thickness of at least 12 millimeters. It is better to entrust the task of calculating the concrete structure and the scheme of its reinforcement to an organization specializing in architectural design. Although the technique of building domed houses is not regulated by specific state regulatory documents, the methodology for calculating the strength and technical characteristics of spherical concrete structures was established in the last century..

The next stage is the construction of a grid of the main wall reinforcement. Steel bars of nominal diameter, the length of which is equal to a quarter of the circumference of the central section of the sphere, are added to the protruding reinforcement by means of welding or threaded connection. After extension, the rods are bent to the axis of the building, forming a dome. Usually, the length of the longitudinal rods is chosen with a margin, cutting off excess reinforcement when mating, which are subsequently used for additional connection of the elements of the reinforcing mesh.

The following can be used as an end connection:

• a ring with an I-beam or channel profile, if you plan to make the top of the dome transparent;
• interfacing of two round steel sheets;
• connecting section in the form of a star made of pipes of the corresponding diameter (the number of vertices is equal to the number of longitudinal elements of the reinforcing mesh).

When the frame has acquired the shape of a hemisphere, transverse ones are added to the vertical rods by welding or knitting with wire.

This technology must use a pre-fabricated pneumatic frame. It is made individually and, when inflated, completely follows the contours of the inner surface of the dome. In those places where windows and doors should be, the frame has protrusions of a given shape and size. Manufacturing a pneumatic frame is the most costly and difficult stage of construction, but since the technology halves construction costs, its price pays off in full.

You can order a frame from companies that manufacture inflatable trampolines, pre-fabricated pneumatic structures or water slides. As a material, it is better to choose a high-density fabric with latex or PVC impregnation. The cost of the frame will be from 50 thousand rubles, the production time is about two months. After use, the product can be sold to any construction company..

All subsequent work is carried out in stages:

1. The pneumatic frame is firmly fixed inside the steel crate and inflates.
2. At the locations of doors and windows on the reinforcing mesh, the dimensions of future openings are marked in the form of protrusions on the frame.
3. The frame is deflated and removed for the duration of welding.
4. Reinforcement is cut according to the markings made. Apertures are edged from all four sides with profile reinforcement in 2-3 rows.
5. The frame is treated with a hydrophobic compound and installed in place.

The final stage of the work is the spraying of the base material on the dome. The process is divided into several stages: the composition is applied layer-by-layer with a layer thickness of 3.5 to 8 cm, depending on the type of material. After the first layer has been applied, but has not yet frozen, special rods-beacons of a fixed length are immersed in it perpendicular to the plane of the frame, along which the thickness of the walls and the uniformity of the spraying will be controlled. Cement-polymer or shotcrete, expanded polystyrene or a combination of different materials can be used as the main wall material. For example, the outer and inner spraying layers are made of shotcrete, thereby providing increased surface strength..

After the final hardening of the mixture, the frame is dismantled, the defects of the spraying in the openings are eliminated, at which the process of erecting the dome ends.

Dome houses on the basis of fixed formwork and factory buildings

Dome construction has become widespread in Russia largely thanks to the systems of permanent polystyrene formwork and spherical block-type buildings. The initial task of these technologies is the implementation of objects of the so-called rapid construction. In this case, the construction of domed houses takes no more than two weeks (excluding the construction of the foundation and internal arrangement).

Both technologies have a number of similar features:

1. The main elements of buildings are produced in the conditions of house-building factories, after which they are transported to the site and assembled there.
2. Expanded polystyrene is used as a starting material for the blocks..
3. The buildings are distinguished by increased energy efficiency: in fact, the domed house becomes a kind of “thermos” due to the high content of heat-insulating materials in the structure. External finishing in both cases is carried out by applying waterproof facade plaster.
4. Any type of foundation can be used as a base, including a lightweight base for a frame house.
5. The delivery set almost always includes a technical design of the building and recommendations for the construction work.

There are also several differences:

1. Block houses do not require additional concrete work.
2. The prefabricated structure of ready-made blocks can be disassembled and moved. Very often the use of such houses is seasonal..
3. Technologies differ in the methods of arrangement of door and window openings.
4. Block buildings, as opposed to formwork, are often supplied fully equipped (including doors, windows, ventilation systems, etc.).
5. The use of fixed formwork somewhat limits the variety of shapes and sizes..

As for the construction technique, it is quite simple. The structural elements, after being delivered to the construction site, are sorted and divided into groups. The first is the basement level: it is attached to the base by means of brackets or anchors. Behind it is the construction of the domed part. The blocks are in the form of honeycombs of the same size and shape. They are fixed to each other with lock or overhead mechanical connections..

If we are talking about buildings with permanent formwork, then concrete pouring can be carried out both after complete assembly, and in its process. In any case, as the main structure is being erected, a reinforcing frame is mounted inside it. The top of the dome is a separately supplied multi-layer unit that can be made as a double-glazed unit in a plastic frame.

After the walls have been erected:

1. Installation of doors and windows:
   • in formwork houses, window and door openings remain smooth. Installation is done in any available way;
   • block structures often have factory grooves and lock (mechanical) connections, which facilitates the installation process.
2. Sealing joints with polyurethane foam.
3. Exterior decoration, installation of window sills, ventilation grills and other fittings.
4. Installation of foundation blind area and installation of drainage channels.

Exterior finishing of formwork buildings requires a layer of rough plaster using fiberglass mesh. In block houses, the outer layer of parts has a special coating (for example, polymer cement), which facilitates the process of facade finishing, or a finished waterproof finish surface with decorative elements.

Installation of floors and partitions

The device of interfloor ceilings is provided mainly in domed houses based on the geosphere and pneumo-frame. Ceilings can be either prefabricated or reinforced concrete. The construction process is quite simple:

1. First, the main frame is assembled from metal or wooden beams. In the first case, T-beams or I-beams are used with “dimes” at the ends. Steel beams are fastened with anchors or pass-through brackets, and screw pins are used to fix wooden beams, which are screwed in from the outside of the building.
2. Supporting structures are connected by ties.
3. The prefabricated hardwood floor is filled with mineral wool and sutured with edged boards or wood-based panels.
4. If pouring reinforced concrete is required, a reinforcing mesh with a mesh size of 10×10 cm and a wire thickness of at least 6 mm is installed in the gaps between the supporting beams..
5. Formwork for pouring concrete is made of OSB-plates, which are attached to the beams using galvanized wire. As a rule, one linear meter of a beam is required from five anchor points.
6. The formwork should be covered with polyethylene, after which the concrete mixture can be poured.

Features and benefits of domed houses

Houses built using any of the dome construction technologies have a number of special properties that cannot be achieved with traditional construction methods. It is thanks to these differences that domed buildings are not just an alternative to cubic houses. They represent a completely new type of structures capable of solving most pressing everyday problems in the absence of any material costs..

Energy saving features

Heating a domed house in winter requires 20–30% less energy than conventional buildings. Firstly, this is achieved due to the unique shape of the house: with the same area, the volume of the domed building is much smaller. In addition, the spherical shape of the room helps to maintain constant natural air circulation, which means that warmer air will not accumulate at the top of the room. This feature is perfectly traced during thermal imaging inspection. There is another trick, thanks to which you can achieve additional savings on heating: if you place panoramic glazing or a transparent top of the dome in the upper part of the building, the house will be additionally heated due to the greenhouse effect.

Unrivaled strength characteristics

Ideally even distribution of the load on the structure is ensured by its spherical shape. No matter what section of the structure is subjected to mechanical action, it will be effectively distributed throughout the entire array. This property is especially pronounced in houses built on the basis of a triangular frame due to the balanced placement of stiffeners and support points. For regions with an unstable climate, domed houses are best suited: due to their streamlined shape, they remain immune to wind gusts of up to 230 km / h.

Maximum savings

As mentioned above, building a house using dome technology saves about 50% of money. Let’s check this statement by comparing a domed house with a traditional one..

Comparison of material costs for the construction of houses of different types

Comparison criteria	Standard one-story house	House built using dome technology
The main parameters building	Total area: 100 m2 Smallest possible perimeter length: 40 m Inner perimeter length: 34.4 m	Total area: 100.24 m2 Outer border radius: 5.65 m Inner border radius: 5.25 m Outer circumference: 35.48 m Inner circumference: 35.08 m
Data about the foundation	Horizontal area: 26.04 m2 Minimum allowable height: 0.7 m Concrete volume: 18.23 m3	Horizontal area: 13.69 m2 Minimum allowable height: 0.4 m Concrete volume: 5.48 m3
Data about the outer walls	Wall thickness: 0.6 m Building height: 2.7 m Wall array volume: 59.62 m3	Wall thickness: 0.4 m Building height: 4.7 m Wall array volume: 57.94 m3
Decorative finishing	External wall surface area: 108 m2 Internal wall surface area: 92.88 m2	External wall surface area: 157.08 m2 Internal wall surface area: 132.95 m2
Roofing	Required	Not required

Estimated cost of the main types of materials, rub.
Appointment	For a standard house	For home in the geosphere	For home on pneumo-frame
Foundation (concrete only)	Per cubic meter m: 2900 In total: 52 867	Per cubic meter m: 2900 Fully: 15,892 + 20%* = 19,070	Per cubic meter m: 2900 Full: 15 892
Walls	Cinder block + Brick Per cubic meter m: 3250 Total: 193 765	Concrete Per cubic meter m: 2900 In total: 168 026	Wood + Minvata Per cubic meter m: 2300 Total: 133 262
Roof	Per sq. m: 2850 In total: 359 100	Not required	Not required
Ceiling slab	Per sq. m: 1100 Fully: 110,000	Not required	Not required
Facade Finishing	Per sq. m: 950 Full: 102 600	Per sq. m: 1300 Total: 204 204	Per sq. m: 500 Total: 78 540
The final cost	818,332	391,300	227,696

^* Strip foundations in this case are almost a quarter higher.

Optimum distribution of space and unrivaled comfort

Due to the fact that there are no load-bearing walls, the domed house has no planning restrictions. It can easily combine living and dining rooms into one spacious room with a high ceiling. A relaxation room can occupy at least half of the entire house, and there will be no problems with installing a jacuzzi in the bathroom. It is noteworthy that during the overhaul, the layout can be changed by transferring the pre-fabricated partitions. In domed houses, there is no need to isolate yourself in closed rooms, trying to protect yourself from irritants: the sphere effectively absorbs sound and at the same time does not let noise from the street through.