Process of production of prefabricated elements
Prefabricated elements (PREFABRICS) can be 2D prefabs and 3D prefabs.
2D prefabs are flat panels and are divided into:
- Walls (facade and partition wall)
- Intermediate floor constructions – mezzanine floor
- Roof structures
Walls
The walls are prefabricated in the production plant as “large composite panels” and include the construction of the wall, which is made of LGS (light gauge steel) profiles, which are filled with thermal insulation and coated on both sides with various types and combinations of coatings, which provide the required conditions for a given wall, such as which are heat transfer coefficient, acoustic protection, fire protection, etc. Filling and lining materials are certified, quality-controlled materials.
Some of the possible sections of a composite wall with LGS construction:
Facade wall with “contact facade” – DEMIT facade
1. Final facade finish
2. Plaster
3. Reinforcement mesh
4. EPS insulation (expanded polystyrene)
5. Adhesive for EPS
6. OSB 3 board
7. LGS load-bearing structure – frame
8. Mineral wool insulation
9. Vapor barrier
10. OSB 3 board
11. Gypsum plasterboard
External Wall with ETICS Facade (DEMIT System) – with Service Cavity
1. Final facade finish
2. Reinforcement mesh and plaster
3. EPS insulation (expanded polystyrene)
4. Adhesive for EPS
5. OSB 3 board
6. LGS load-bearing structure – frame
7. Mineral wool insulation
8. Vapor barrier
9. OSB 3 board
10. Substructure
11. Service cavity
12. Fermacell board
Partition Wall – with Acoustic Isolation Tape on LGS Profiles
1. Gypsum plasterboard (2 layers)
2. Acoustic isolation tape
3. LGS load-bearing structure – frame
4. Mineral wool insulation
5. Gypsum plasterboard (2 layers)
Ventilated Facade – Brick Cladding
1. Facade brick
2. Substructure
3. Brackets
4. Stone wool insulation
5. OSB 3 board
6. LGS structure
7. LGS reinforcement
8. LGS floor beam
9. Mineral wool insulation
10. LGS frame
11. Vapor barrier
12. Fermacell board
Facade with Slats
1. Facade slats
2. Plaster
3. Stone wool insulation
4. Substructure
5. OSB board
6. LGS structure
7. LGS floor beam
8. Mineral wool insulation
9. LGS reinforcement
10. LGS frame
11. Vapor barrier
12. Fermacell board
„Ventilisana fasada“ – HPL fasada ili ALU BOND
1. ALU BOND (ili HPL)
2. pod – konstrukcija
3. LGS podni nosač
4. kamena vuna
5. OSB ploča
6. mineralna vuna
7. LGS konstrukcija
8. LGS ojačanje
9. LGS konstrukcija
10. LGS frame
11. parna brana
12. Farmacell ploča
Ventilated Facade – WPC or Timber Cladding
1. WPC facade panel or timber cladding
2. Substructure
3. Stone wool insulation
4. OSB board
5. Mineral wool insulation
6. LGS floor beam
7. LGS structure
8. LGS reinforcement
9. LGS frame
10. Vapor barrier
11. Fermacell board
The degree of prefabrication of the 2D prefab wall means a completely finished wall, with all installed internal or external carpentry (windows and doors) and a flexible electrical hoses passed through the wall and connections – convenience outlet for electrical installations. After the assembling of the wall on the construction site, the remaining works are the finishing of the joints, pulling the electrical cables through the hoses, the final coat of skimming and painting on the inside, as well as the facade coating on the outside, if it is a „contact facade – DEMIT“.
Wall Panel – Example (Production Stages)
1. LGS structure
2. Fixing systems
3. Wind barrier
4. Mineral wool insulation
5. Vapor barrier
6. OSB board
7. Service installations – substructure
8. Gypsum plasterboard
9. Neopor (external insulation)
10. External joinery
11. Reinforcement mesh and adhesive
Wall Panel Installation
In the production of prefabricated walls, it is possible for the finished walls to be mounted on the skeleton structure of the buildings by “special assembly” – as shown in the following picture:
Mezzanine structures:
Mezzanine constructions are 2D prefabs, which, depending on the span, as well as the requirements in terms of the type of floor slab, can be made in several different ways. Constructively, at small spans, it can be used as a LGS construction system consisting of C girders, as double C girders („back to back“) or as braced girders.
Back to back C section
The thickness, quality of the sheet metal in terms of galvanization and tensile strength is determined by static calculation.
The floor slab of the panel of the mezzanine structure can be wooden (OSB board), wood-cement, light concrete as well as concrete, casted on site.
The degree of prefabrication of the mezzanine structure involves the production of a structural panel, floor slab and mineral wool filling. The suspended ceiling under the mezzanine structure is mostly done on site, due to the possibility of fixing the mezzanine structure to the walls, as well as the distribution of electrical installations in suspended ceiling. Also, the floor covering above the mezzanine structure is mostly done on site.
Roof structures:
In the case of „flat roofs“, the roof panels are made in the same way as mezzanine structures, with the fact that conical laths are placed over the LGS structure, which ensure the projected fall of the flat roof.
The degree of prefabrication of the flat roof panel (“stacked composit roof”) includes the construction of the LGS structural frame, the installation of the vapor barrier, thermal insulation filling, fall battens, panels, geotextiles and roof membrane (PVC, TPO, EPDM..). Welding of the roof membrane is carried out on site, on the panel joints. “Flat roof” can also be made with TR sheet.
In the case of pitched roofs, which are covered with traditional roofing material, such as for example tiles, roof prefabriceted panels are also made.The degree of prefabrication of the roof panel includes LGS structural frame, vapor barrier, filling with thermal insulation, laying of plywood, PPVN foil, longitudinal and transverse lath. Covering with tiles is done on the building.
Roof Panel – Example (Production Stages)
Roof Structure Installation with Synthetic Roofing Membrane
1. LGS structure
2. Vapor barrier
3. Mineral wool insulation
4. Timber battens for flooring
5. Additional mineral wool
6. Plywood board
7. Geotextile
8. Roofing membrane
External Installation Principle
Final Assembly of 2D Prefabricated Elements on Site
1. Concrete foundation
2. Waterproofing
3. Base timber plate for fixing
4. Wall installation
5. Installation of adjacent wall panel
6. Interior view
7. Installation of intermediate floor panel
8. Connection between floor and wall
Installation and Finishing Works
Factory production is based on a prefabricated production unit—the COMPOSITE PANEL—used for external facade walls, internal partition walls, intermediate floor structures, and roof structures. The appearance of the panels and the method of installation have already been presented in the previous section.
NOTE:
Prefabricated buildings are delivered without final fit-out works—the structure is installed in a “shell and core” (grey phase).
Foundation works are calculated separately (in Serbia, we perform foundations on-site, while internationally the foundation is executed by the Investor based on our calculations and technical guidelines).
External and internal joinery (standard quality) is included in the cost of facade and partition walls (higher-quality options, such as timber or aluminum systems, can be selected by the Investor and are priced separately).
Only conduits (without cables and fittings) are installed within the walls; electrical wiring and accessories are completed on-site and charged separately—the selection of fittings is made by the Investor.
Ceramic tiles and sanitary equipment selected by the Investor are not included in the production cost calculation.
Final floor finishes (e.g., parquet) are not included in the intermediate floor structure and are selected and priced separately.
Finishing works such as skim coating and painting are not included—they are carried out on-site and charged separately.
Heating and air conditioning (HVAC systems) are not included in the price.
Transportation and installation costs are calculated separately, depending on the region where the building is assembled.
Prefabricated Elements Production Process – Workflow Diagram
- Projektovanje i izrada Idejnog rešenja (IDR) , izrada Projekta za građevinsku dozvolu (PGD), izrada radioničkih crteža za svaki pojedinačni element – panel (zidove, međusprtanu konstrukciju, krovove)
- PROIZVODNJA PROFILA
– Slitovanje lima na slitarici (u ovoj verziji se kupuje gotov “slitovani” lim)
– Proizvodnja profila na LGS mašini – FRAMER
– Lagerovanje proizvedenih profila u soške - KROJENJE PLOČA
– Krojenje ploča na raskrojaču
– Lagerovanje iskrojenih ploča na regale - HORIZONTALNA MONTAŽA 2D PREFABRIKATA – PANELA
– Montaža LGS konstrukcije na stolu za montažu LGS ramova
– Montaža zidnih i podnih/krovnih kompozitnih panela na “Leptir” montažnim stolovima I montažnim fiksnim stolovima sa podižućim rolerima - FINALNA VERTIKALNA OBRADA I MONTAŽA 2D PREFABRIKATA – PANELA
– Finalna montaža panela na “šinama za vertikalnu obradu” - TRANSPORT 2D PREFABRIKOVANIH PANELA DO GRADILIŠTA
- MONTAŽA 2D PREFABRIKOVANIH PANELA (ZIDOVI, PODOVI/KROVOVI) NA GRADILIŠTU SA ZAVRŠNIM RADOVIMA
- Design and development of the Concept Design (IDR), preparation of the Building Permit Design (PGD), and production of workshop drawings for each individual element—panel (walls, intermediate floor structures, roofs)
- PROFILE PRODUCTION
- Sheet metal slitting on a slitting machine (in this version, pre-slit coils are procured)
- Profile production on an LGS machine – FRAMER
- Storage of produced profiles in racks
- BOARD CUTTING
- Cutting boards on a panel saw
- Storage of cut boards on racks
- HORIZONTAL ASSEMBLY OF 2D PREFABRICATED ELEMENTS – PANELS
- Assembly of LGS structure on LGS frame assembly tables
- Assembly of wall and floor/roof composite panels on “butterfly” assembly tables and fixed assembly tables with lifting rollers
- FINAL VERTICAL PROCESSING AND ASSEMBLY OF 2D PREFABRICATED ELEMENTS – PANELS
- Final panel assembly on vertical processing rails
- TRANSPORT OF 2D PREFABRICATED PANELS TO SITE
- INSTALLATION OF 2D PREFABRICATED PANELS (WALLS, FLOORS/ROOFS) ON SITE WITH FINISHING WORKS