- What you need to know
- Foundation for a metal frame
- Frame system structure
- Overlapping and roofing
- Thermal insulation, sound insulation and facade decoration
Modular-frame technology makes it possible to build residential buildings in the shortest possible time with a relatively small material consumption. We will consider a typical building instruction using a lightweight thermal profile and structurally insulated panels..
What you need to know
Houses made of metal structures and self-supporting insulated wire belong to pre-fabricated buildings. The reliability of this technology is not called into question, but only if two key rules are observed.
First: before the start of construction, the entire range of design and survey activities was completed, specifications were drawn up, detailed drawings of plans and sections of the building, and the assembly procedure was described. This is the most difficult stage: largely due to the lack of technical and regulatory documentation, you can only focus on the Eurocode EN 1993-1-3, which describes the work with pre-fabricated steel structures.
An example of an assembly drawing of a panel from LSTK
Second: during the assembly process, the entire list of technical requirements was fulfilled, the work was performed by qualified personnel. We will consider the key points of construction based on LSTK, which will help to maintain detailed control over the actions of contractors or quickly navigate industry rules if the work is carried out on our own.
Foundation for a metal frame
Of all the types of foundations in the context of prefabricated metal structures, only three are worth seriously considering.
The first one is a pile-grillage foundation, which has an ideal ratio of material consumption and bearing capacity. Buildings based on LSTC are lightweight, even on soft and unstable soils, they demonstrate good integrity and seismic resistance.
The main task comes down to supporting the piles on a dense layer below the freezing depth. As a rule, pile drilling depth does not exceed 1.8–2.5 meters. The grillage is made with two reinforcement lines with 35 mm protective layers. With the help of corner anchors, embeds are added to the reinforcement for a rigid connection of the foundation with the frame.
The second suitable type is MZLF. It makes sense to arrange it if you need to organize a basement or an underground garage. The technology of casting a basement monolithic structure is quite standard; to save materials, foundations with a cascade section are cast or they are expanded in the lower part.
The third recommended foundation for houses on a metal frame is the USB. Its execution is also quite standard, but the Swedish plate is justified only when building a passive house. Another argument in favor of an insulated slab may be the desire to arrange an underfloor heating system. Due to the small thickness and, as a consequence, the low heat capacity of the slab, it is recommended to arrange heating with jet pipes.
Frame system structure
For the construction of the supporting frame system, two types of structures are used. Steel metal structures are optimal due to their low cost and ubiquity; they should be used in buildings with low claims for heat conservation. In private construction, lightweight structures are more interesting, the profiles of which represent weaker cold bridges due to the lengthening of the heat outflow path and have a total weight of 30–40% less than frames made of structural steel. Other advantages are high work culture, fast connection speed, no welding and rigging.
Most kits are pre-assembled at the factory, and the contractor only needs to correctly reproduce the order of joining the parts. But often they refuse to design the frame, so it will be useful for independent craftsmen to study the main elements of the architecture of the wall structure.
Fortunately, the LSTK is based on the principles that are familiar to many from the experience of working with frames for plasterboard sheathing: all the same rack and guide profiles and additional. fittings for their spatial connection. The types of thermoprofiles and the principles of their use can be easily traced when studying the installation procedure:
- U-shaped guide profiles are installed along the section in the plan of load-bearing walls and columns, they are attached to the embedded foundation.
- Rack elements are inserted into the guides with a pitch of 60-120 cm, which are connected by horizontal crossbars at several levels: under window openings and ceilings.
- Mauerlat is carried out with a final guide profile.
- Solid sections of the walls are filled with additional posts and braces, made with segments of the C-shaped rack-mount profile. Jumpers from T-profiles are added to decorate openings.
- Crossbeams for floors and roof support are duplicated by lintels to form a reinforced truss with two parallel belts.
- Fastening of system elements is carried out with bolted connections, rivets or self-tapping screws.
Each of the wall frame systems is built according to an individual calculation of concentrated nodal and distributed loads, by analogy with a timber frame house. A logical question arises: why not replace LSTK with heavier metal structures that have the same configuration, but guarantee a solid margin of safety?
In reality, thermoprofile and metal structures have ardent supporters in their own camp, who diligently prove the merits of their technology. Only one thing can be said with certainty: LSTK requires a deliberate and balanced attitude to each stage, while metal structures are more tolerant of an amateurish approach, but less technological.
Overlapping and roofing
The overlap device is quite simple. With a short span length, the main load is taken by an I-beam or U-section thermal profile. With a considerable length of spans, they are replaced by two-belt gantry trusses.
The space between the beams is filled with mineral wool insulation after the filing profile is attached and the rough ceiling is installed. After that, a profiled sheet is laid on the floor of the upper floor, along which the screed is made with polystyrene concrete with light polymer reinforcement.
The roofing system is of the same type as for timber structures. The rafters are assembled from a rack-mount or I-beam thermal profile, the crate is made with a hat section profile. Here it is worth making an important reservation: during the construction of MK and LSTK, they can be combined, while the auxiliary elements of the thermoprofile should rely on a heavier system, but not vice versa.
Thermal insulation, sound insulation and facade decoration
The cladding of the frame made of metal structures is carried out mainly with structurally insulated panels. At the same time, the cavities of the frame provide the opportunity to arrange an additional layer of insulation, which is most often performed with ecowool.
The best insulation parameters can be achieved with the construction of a solid fence made of self-supporting insulated wire with a metal sheath around the frame system. The use of wooden panels with the placement of the frame in technological grooves is much less common..
As in most cases, wadded-type heaters require protection with a vapor barrier from the inside and wind protection from the outside, if self-supporting insulated wire is not involved in the enclosing structures. This option is also quite widespread: the metal frame is an excellent basis for attaching ventilated facades. This type of exterior finish is acceptable if the wall thickness meets the thermal insulation requirements..
The propagation of constructional noises in a house made of metal structures is anticipated by the separation of rack and auxiliary elements with rubber inserts, which work on the principle of silent blocks for an automobile suspension. This element is often neglected due to the fact that the rigid bonding of structural elements and the abundance of porous filler in themselves cause high noise absorption.