Prefabricated frame houses are in high demand due to the cheapness and technology of accelerated installation. Obviously, paying for these advantages has a wide range of design flaws like mechanical weakness and low life. On the other hand, such projects are not always designed for long-term use, but even in this case, not everyone is ready to put up with the disadvantages of a building that affects comfort. The technology of the frame-filling house allows one of these disadvantages to be eliminated. We are talking about thermal insulation, and in some cases, strengthening the structure.
General information about backfill buildings
The technology is based on the principles of the Canadian prefabricated frame method of building private homes. As a rule, these are single-story buildings of a small area. The construction process is carried out using a ready-made house kit, which includes all the necessary materials. The supporting structure is constructed according to the traditional scheme with the use of frame racks. The fundamental difference between almost all frame houses is that walls and partitions do not fulfill the direct function of retaining horizontal floor floors with the load imposed on them. They serve only as walling. In turn, the bearing function is separately transferred to the metal and reinforced concrete frame racks. Sheathing can be made of a variety of materials from chipboards or OSB sheets to brick and timber.
What is the backfill structure? It differs from a conventional frame construction in its approach to thermal insulation. The fact is that the walls of the filling houses inside have a cavity for filling with bulk materials. Actually, this is where the name of the technology comes from. If a standard frame house contains mineral wool in the wall structure with film vapor and water insulators, then in backfill structures the role of insulation is played by sand (perlite), peat or sawdust. It is densely packed so that there are no voids left. The walls themselves are made with lining of boards or other panel materials used in frame-panel construction.
In general, we can conclude that the backfill building is a prefabricated structure, which is built from start to finish on the construction site, has a system of load-bearing racks and provides for the laying of bulk insulation in the walls.
Material requirements for backfill construction
The base of the frame is formed by wooden supporting structures, which should be made of coniferous lumber, dried in a dry room. For elements that will be located in the area of the foundation or basement (at a level below the ground or less than 25 cm above the ground), they must also undergo antiseptic treatment. It protects wood from decay and physical destruction.
According to SNiP 2.03.11., Facing, finishing, roofing, insulation, sealing and other building materials for frame houses must also comply with local conditions of use.
Separately take into account environmental requirements. This is one of the aspects that distinguish a frame-filling house from ordinary prefabricated panel buildings. It is the rejection of synthetic heat-insulating layers in favor of bulk fillers that causes a higher environmental cleanliness of the structure. The standards also approve the rules for the use of wood-based panel materials, which should not contain toxic inclusions like formaldehyde above 5 mg per 100 g. If you can’t refuse them, the material will have to undergo a preliminary detoxifying primer.
Often, asbestos-containing elements are also used in frame housing construction - in particular, for interior decoration. Such materials during installation should either be faced with glazed tiles, or covered with waterproof paints and varnishes. Such treatment is required to protect against the effects of disinfectant solutions in household care.
Safety regulations
Features of the operation of prefabricated frame houses, among other things, are associated with fire threats and low structural strength. Both factors, respectively, determine higher requirements for the prevention of similar threats.
As for fire safety, it is provided in two ways:
- Replacement or complete rejection of combustible or at least flammable materials in the main structure. The same OSB cladding quickly burns out, transferring the flame to the supporting panels and walls, if in principle they can burn. Particular attention is paid to insulators and insulating filler. If wood chips or sawdust are used, then the casing must be non-combustible.
- The second way to increase the fire safety of a tomb house on a wooden base involves the creation of protective fire-resistant barriers. It can be special impregnations for the wood structure, and quite functional structural elements. For example, there are modifications of drywall sheets and basalt wool that do not support combustion and serve as full layers of the inner lining.
Rules for ensuring the mechanical strength of the house
According to experts, the mechanical strength of correctly constructed frame houses allows them to serve more than 50 years. Structural reliability is also supported in many ways. As already noted, much will depend on the carrier system of the racks. These are vertical and horizontal elements that form power belts in the form of lower and upper harnesses. Also, jumpers over the openings are introduced into this system. Racks should be based on the overlap of each floor, distributing the load over the entire area.
Strengthen the design and by incorporating more durable materials than wood. For example, there is a technology of a combined brick-and-tomb house, in which one or more brickwork is used. Actually, the masonry acts as a supporting belt strapping, increasing the load capacity of the base. But it is important to consider that a brick with a monolithic structure will not allow proper thermal insulation to be performed - moreover, cold bridges can form at the joints. An alternative will be the use of polystyrene foam blocks. These are modular hollow wall segments that can be filled with any loose insulation.
Installation of the foundation of the tomb house
The site for future construction is being cleared under the strip foundation. Debris, stones and vegetation are removed along with the roots. If there is an anthill in the area of the site, the contaminated soil is replaced to a depth of 30 cm. The soil structure at the bottom of the pit should maintain a smooth geometry. If it is planned to lay communications, then the contours of the trench are filled with dense bulk material, which is then rammed and concrete. Next, the width of the walls is determined. It is possible to build a filling house with external and internal walls with a thickness of 20-50 cm. The specific value is determined by the number of floors with ceilings. Accordingly, for a one-story house, walls with a thickness of 20-30 cm are calculated, and for a three-story house - about 50 cm.
For the supporting columns, foundation soles are arranged. The step between them is calculated individually - depending on the number of floors, the structure of the supporting system and the nature of the groundwater. How to make a backfill house on a stepped foundation? Such structures are organized on slopes so that the length of the horizontal section is at least 60 cm. It is also possible to use a columnar foundation. In this case, the piles are located around the perimeter of the supporting frame with a step of 2-3.5 m.
Frame mounting
The supporting structure is formed by pillars, columns and pilasters. The calculation of this system takes into account the load on the floor, as well as external influences like the wind. Provide a trench house with power elements of the frame should start from the basement. At the basement level, racks with internal walls are placed, which in this case also perform a supporting function, supporting the first and most critical ceiling.
The columns are fixed in the center of the foundation. External rods are additionally connected to the ceilings by anchor bolts. Usually, metal and reinforced concrete structures are used, but sometimes the introduction of wooden poles is allowed. In such a system, it is important to provide insulation of the wood material from the concrete structure. This is done using plastic wrap. Metal poles are mandatory elements of the supporting frame of two-story tomb houses. With your own hands, you can also make pillars of masonry or brickwork. The standard parameters for such structures in width and depth look like this: 29x29 or 19x39 cm.
Pilasters can also be used as an addition. They are arranged in the basement walls, the thickness of which is not more than 14 cm. Pilasters are provided at reference points relative to the ceiling elements. Mounting is performed over the entire height at the junction with the walls of the basement.
Wall Features
For the walls, a frame power base is also created in the form of vertical posts and auxiliary horizontal support nodes. Lintels are installed above the openings, and throughout the entire supporting system of columns, strapping belts are mounted - at least from above and from below. The wall covering of the tomb house is made of hard sheet or plate material. Panels should correspond to the loads from the own mass of the house floors and from the wind. If rigid sheathing is excluded, then additional reinforcement with diagonal ligaments or spacers will be required.
It is advisable to fill the walls with a heater in warm time, so that the risks of waterlogging of the material are initially minimized. In the process of filling it is important to exclude voids, openings, gaps and underfilled areas. Such defects affect not only thermal conductivity, but also structural integrity. Wall niches can be provided with sawdust, wood concrete, sand, expanded clay, etc. The cheapest and most practical option will be to install a trowel house from sawdust, which can be obtained free of charge and in the right amount at sawmills. Another thing is that preliminary processing of the material is required. Experts recommend that the sawdust be thoroughly dried, pressed, and mixed with cement, which eliminates the risks of waterlogging of the filler during operation of the house. If the task is to increase the structural reliability of the walls, then it is better to use an adhesive binder instead of cement. It is advisable to choose formulations with antiseptic and refractory properties.
The exterior of the house
Since the walls are mainly designed for the enclosing, and not for the power bearing function, it is important to initially provide a solid base for fastening the outer decorative material. As a rule, this function is performed by the crate - a structure made of wooden planks and bars, which is mounted on the main wall cladding panel and serves to perform the subsequent fixing of the cladding. The following materials can be used as decoration:
- Wooden plank. It can be wide slats, and lining with lock grooves. Reviews of tiled houses with this design emphasize the advantages of natural texture, environmental cleanliness and ease of installation. On a wooden crate, you can mount the board with ordinary nails with putty and biological treatment.
- Siding. Also convenient in installation material, which is a plastic, wood or metal panel. It is more practical to use aluminum sheets that weigh a little and look quite presentable. The only drawback is that aluminum is easily deformed, but it is quite simple to restore it.
- Block house. An imitation of the texture image of a classic metal-based log house. In fact, the combination of siding and boards - semicircular sheets are fixed to the crate with hardware and interlocked with each other via a joint-groove connection.
Repair work
Since the house is largely composed of natural wood components, periodically there will be a need to repair sites that have undergone biological destruction. This mainly applies to wall cladding and internal insulation. How to restore the design of the old tomb house? Damaged areas, subject to the presence of a small affected area, are literally cut with a chainsaw. During the cutting process, it is important to avoid damage to the columns and racks associated with the wall structure. The embedded bar, board or plate material is replaced with new analogues with the performance of sealing. If the entire segment has been rotted, it should be removed completely without separate clippings.
If there are signs of damage to the internal wall filler (rotting odor, emerging moisture, softening of the structure of the wall material), then the lining is not necessary to dismantle. The same sawdust is replaced with a new loose insulation, but first all the foci of decay or damage of a different nature in the wall niche should be eliminated. In this part, the repair of the filling house will consist in the complete antiseptic treatment of the back surfaces of the cladding. By the way, for the initial exclusion of direct contact between the filler and the surface of the wall, you can lay the material in thick plastic bags, and then tightly place them in the construction niche.
Technology benefits
As a kind of frame construction, a house with loose wall filler gives a lot of advantages in terms of organization of construction. They are expressed in the optimization of work processes, cheaper materials, increased construction speed, etc. Even in comparison with traditional wooden houses, this method will have noticeable organizational advantages. Against the background of other frame buildings, the pros and cons of the tomb house will also be very noticeable. Bulk filler, unlike mineral wool, polystyrene foam and other synthetic insulators, provides an environmentally friendly and cheap thermal barrier.
Technology disadvantages
You should also start with the general features of frame houses, which apply to trench buildings. The disadvantages will include low reliability, restrictions on the implementation of various add-ons and high fire safety requirements. Like the advantages of the tomb house, its disadvantages are largely determined by the technology of using loose heaters. Organic fillers are more susceptible to biological destruction, burning and are often eaten by insects. In addition, they are beneficial soil for the life of rodents, which can cause noticeable damage to the structure. Accordingly, there are additional requirements for maintenance and maintenance of the structure of the house, which will include the need for regular flame retardant, disinfectant and biological surface treatments.
Conclusion
With all the limitations and shortcomings, the filling structures make it possible to build energy-efficient and comfortable modern housing. For a relatively small amount, it is possible to build a fully functional and durable filling house from sawdust in 1-2 floors. Another thing is that it will be necessary to maintain the named operational properties by special measures. They relate to the care of sensitive construction materials, the main of which will be wood. Numerous impregnations, primers and paint coatings with protective qualities help to increase its working life.