Light Steel Frame (LGS) construction is built around a precise (Steel Frame Layering) , multi-layered system that enhances structural strength, thermal performance, acoustic comfort, and long-term durability. Each element of the building—roof panels, outer wall panels, and floor panels—is engineered with a carefully designed sequence of layers. These layers work together to create a high-performance building envelope capable of resisting environmental loads, improving energy efficiency, and ensuring exceptional comfort for occupants.
In modern cold formed steel construction, layering is not simply a matter of stacking materials; it is a strategic engineering discipline. Every layer is selected for a specific purpose and tested to perform a unique function. Structural boards increase rigidity and load-bearing capacity, insulation layers improve thermal and acoustic balance, moisture-control membranes protect the structure against condensation, and finishing materials provide fire safety, airtightness, and overall durability. When combined, these elements form a lightweight yet incredibly resilient system that outperforms many traditional construction methods in both speed and quality.
Beyond strength and insulation, proper layering also plays a crucial role in building lifecycle performance. Correctly designed assemblies reduce thermal bridging, minimize energy loss, prevent mold formation, and create more stable interior environments year-round. This is why LGS construction is favored in regions with extreme climates, strict energy regulations, or fast-track project requirements. The multi-layered approach ensures buildings remain comfortable, efficient, and low-maintenance over decades.
The graphics below illustrate three core components of an LGS building: the Roof Truss Panel, the Outer Wall Panel, and the Floor Panel. Although their individual functions differ, they all share the same engineering philosophy—a pursuit of maximum efficiency, safety, precision, and performance through intelligent layer sequencing. Together, these panels form the backbone of a modern, reliable, and high-precision light steel structure, setting new standards for future-focused construction.
*This document and its illustrations were created to provide guidance for newcomers to the steel frame construction market.
Steel Frame Layering
OUTER WALL PANEL Layer-by-Layer Functional Explanation
The outer wall panel in a light steel frame (LSF) structure is engineered as a high-performance building envelope. Each layer contributes to structural strength, thermal efficiency, fire safety, acoustic comfort, and long-term durability. Below is a detailed explanation of all 12 layers shown in the exploded model.
1. Interior Wall Paint
The final interior finishing layer that provides aesthetic appearance and surface protection. It forms a smooth, clean, and durable interior environment.
2. Primer Coat
Applied under the paint to ensure adhesion, enhance durability, and create a uniform base. It prevents peeling and improves the overall quality of the finish.
3. Satin Plaster
A fine finishing plaster that levels and smooths the surface. It creates the ideal substrate for paint application and enhances interior wall aesthetics.
4. Mesh + Adhesive Layer
A reinforced crack-preventing layer used to strengthen the plaster. It increases wall surface durability and prevents micro-cracks caused by movement or temperature changes.
5. Gypsum Board (White or Green or Red)
A lightweight interior sheathing board:
- White Gypsum Board → standard interior use
- Green Gypsum Board → moisture-resistant, used in kitchens, bathrooms, and humid environments.
- Red Gypsum Board → fire-rated, provides enhanced fire resistance for safety-critical areas.
It also provides contributes to thermal and acoustic performance.
6. OSB Board
A rigid structural layer providing panel stability. It also offers strong screw-holding capacity, making it ideal for mounting cabinets, shelves, or interior fixtures.
7. Light Steel Frame
The main structural skeleton of the wall. Made from cold formed steel, this frame ensures:
- high load-bearing capacity
- excellent earthquake resistance
- dimensional stability
- long-term durability without warping or rotting
This is the core element of the LGS wall system.
8. Rock Wool
Provides high-performance thermal and acoustic insulation. Rock wool is also A1 non-combustible, significantly improving fire resistance. Rock wool thickness may vary depending on the geographical zone or the construction environment.
9. Exterior OSB Board
Adds structural rigidity to the outer section of the wall and protects the insulation layer. Acts as a base for exterior water-resistant boards.
10. Water-Resistant Gypsum Board (Exterior Gypsum / Boardex)
A moisture-resistant outer sheathing layer designed to withstand rain, humidity, and exterior climate conditions. It enhances façade durability and protects internal components.
11. XPS / EPS Insulation Foam Board
A high-density thermal insulation board that reduces thermal bridging. Improves building energy efficiency and contributes to a stable indoor climate.
12. Exterior Cladding Material
The final protective and decorative outer layer. Can be brick, wood, composite panel, siding, or other façade materials. Provides aesthetic value while protecting the building from external factors such as UV, wind, and rain.
ROOF TRUSS PANEL Layer-by-Layer Functional Explanation
The roof panel of a light steel frame structure is designed as a multi-layered system that ensures superior weather resistance, structural rigidity, thermal comfort, and long-term durability. Each material has a specific engineering purpose, and together they create a high-performance roofing solution suitable for modern steel buildings.
1. Finishing Material
The outermost roofing layer that provides strong protection against rain, snow, UV radiation, and temperature fluctuations. It delivers:
- long-term weather durability
- waterproofing at the top surface
- an aesthetically pleasing finished roof appearance
2. Double-Sided Batten Frame (Optional)
A structural support grid placed beneath the tiles. Its main roles are:
- securing the tile covering
- creating an air ventilation gap
- preventing condensation and moisture buildup
This airflow channel significantly extends the lifespan of the roof assembly.
3. Waterproof Membrane
A critical protective barrier installed under the batten frame. It ensures:
- complete resistance to water penetration
- protection against rain and melting snow
- prevention of moisture transfer into insulation or interior layers
Even if water passes through tiles, the membrane keeps the internal roof structure dry.
4. OSB Board
A structural decking layer that provides rigidity and a stable base for the membrane and upper materials. It enhances:
- overall stiffness of the roof
- load distribution
- durability against wind and tile weight
This board is essential for maintaining roof geometry.
5. Rock Wool
A high-density thermal and acoustic insulation layer. Key advantages include:
- excellent heat retention and energy efficiency
- superior sound absorption
- non-combustible A1 fire resistance rating
Rock wool significantly improves the comfort and safety of the building. Rock wool thickness may vary depending on the geographical zone or the construction environment.
6. OSB Board
he secondary internal decking layer that:
- supports the insulation
- increases structural rigidity from below
- enhances resistance against deflection and deformation
Acts as a stabilizing counterpart to the top OSB panel.
7. Steel Roof Truss
The primary load-bearing framework of the roof. Manufactured from cold formed steel profiles, this truss provides:
- lightweight but extremely strong roof support
- exceptional resilience during earthquakes
- corrosion resistance and long-lasting structural integrity
- precise manufacturing with minimal installation errors
The steel truss system forms the backbone of modern LGS roof construction.
FLOOR PANEL Layer-by-Layer Functional Explanation
The lattice joist floor system in a light steel frame structure is engineered to deliver exceptional strength, vibration control, fire resistance, and long-term stability. Each layer plays a specific role, contributing to the overall performance of the floor assembly. Below is a detailed breakdown of all 7 layers shown in the exploded model.
1. Interior Floor Finishing (Tile, Laminate, or Wood)
The topmost visible surface of the flooring system. Provides:
- aesthetic appeal
- durability for daily use
- a comfortable walking surface
Different materials can be selected based on the building’s design requirements and functional needs.
2. Adhesive Mortar Layer
A bonding material applied beneath the floor finish. Its function is to:
- secure tiles, laminate, or other finishes
- prevent detachment or movement
- enhance overall surface stability
A strong adhesive layer ensures long-lasting and uniform flooring.
3. Leveling Concrete Layer
A thin screed or leveling layer that corrects surface imperfections. It ensures:
- a smooth and perfectly even floor
- proper alignment before installing the finish
- improved load distribution
This layer is essential for precision flooring applications. Leveling concrete height may change depending on the smoothness of the structural concrete surface. If the structural concrete is already smooth, this layer can be applied very thin or may not be required at all.
4. C25–C30 Structural Concrete
The main structural mass of the floor system. This concrete layer provides:
- high compressive strength
- improved structural rigidity
- elimination of floor vibrations, noise, and deflection
- load-carrying capacity suitable for multi-storey buildings
Its density also enhances acoustic performance, reduces vibrations when walking on upper floors, and improves thermal efficiency.
5. Reinforcement Steel Mesh
Embedded within the concrete to enhance structural integrity. Its benefits include:
- preventing cracking
- distributing loads uniformly
- increasing durability
- improving concrete’s tensile strength
This reinforcement is essential for long-term performance.
6. Corrugated Steel Panel (Steel Decking Sheet)
A shaped steel layer functioning as the formwork for poured concrete. It provides:
- strong bonding between steel and concrete
- increased stiffness and load distribution
- reduced construction time by eliminating traditional formwork
- added fire and structural resistance
The profile design mechanically locks the concrete in place.
7. Steel Floor Joist (Lattice Joist System)
The primary load-bearing framework of the entire floor system. Manufactured from cold formed steel, it offers:
- exceptional strength with minimal weight
- long-span capability
- high earthquake resistance
- reduced deflection and improved floor comfort
- openings for MEP (mechanical, electrical, plumbing) routing
This lattice design maximizes structural performance while minimizing steel usage.
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This document contains Light Steel Construction (Cold Formed Steel) layering details. These illustrated arrangements may vary depending on the specific construction requirements. Layers (adding or removing extra layers) may also change based on the geographic location and building usage. All illustrations, scripts, and information were created by UNBAK LGS Machinery CO LTD.
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