Steel Frame Construction with Fiber Cement Board: Complete System Guide
How to use CE-certified fiber cement board in lightweight steel frame (LSF) construction for facades, internal partitions, and fire-rated assemblies. Stud spacing, fixing guidance, and system specifications.
Steel Frame Construction with Fiber Cement Board: Complete System Guide
Lightweight steel frame (LSF) construction is widely used across Europe for commercial, residential, and modular buildings. Fiber cement board is one of the most compatible sheathing solutions for steel frame systems, offering non-combustibility, moisture resistance, and CE-certified performance. This guide covers everything you need to specify and install Terasun TSM fiber cement board in steel frame applications.
Why Fiber Cement Board for Steel Frame?
Steel frame buildings have specific requirements that fiber cement board meets better than wood-based alternatives:
1. Non-combustibility Steel requires fire protection. Terasun TSM achieves Class A1 (non-combustible). The tested wall assembly reaches E 120 / EI 90 / EW 120 — meaning the wall system can resist fire for up to 120 minutes. This enables fiber cement board to be part of the fire protection system itself.
2. Moisture resistance Steel is susceptible to corrosion if moisture becomes trapped. Fiber cement board at EN 12467 Category A does not retain moisture or act as a moisture source. It will not swell, shrink, or delaminate in humid conditions, helping to maintain a dry cavity.
3. Dimensional stability Steel frame structures have very low thermal movement in the framing but significant movement in the facade skin. Fiber cement board's low moisture movement coefficient (<1% Category A) means joints remain stable over time.
4. Weight At 9.96 kg/m² for 12 mm board, fiber cement board places a predictable and manageable load on the steel frame fixings and purlins.
Recommended Systems for Steel Frame
#### Exterior Ventilated Facade
The most common system for steel frame commercial buildings:
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Steel stud frame (100–200 mm, 400–600 mm centres)
→ Mineral wool insulation between studs
→ Wind-tight membrane (breather membrane)
→ Counter battens / Z-profiles (aluminium or galvanised steel, 50–100 mm cavity)
→ Terasun TSM fiber cement board (8–12 mm)
→ Surface finish: painted, untreated, or rendered
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Stud centres: 400 mm or 600 mm. For 8 mm board on 600 mm centres, verify deflection with the technical data sheet. For 10–12 mm board, 600 mm centres are standard.
Fixing: A4 stainless steel self-drilling screws for steel substrates. Pre-drill board at 3 mm for 12 mm board. Edge distance minimum 25 mm from cut edges, 20 mm from factory edges.
Movement joints: Provide vertical movement joints at maximum 4,800 mm centres. Horizontal joints at each floor or every 3,600 mm.
#### Fire-Rated Internal Partition (Steel Stud)
For fire compartmentalisation in commercial and residential steel frame buildings:
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Terasun TSM 12 mm both faces
→ 75–100 mm steel C-studs at 400 mm centres
→ Mineral wool infill (min. 60 kg/m³ density)
→ Tested assembly: E 120 / EI 90 / EW 120 (FIRES-CR-284-25-AUPE)
``
*Important: Fire classification applies to the tested assembly only, using 12 mm Terasun TSM boards. Do not substitute other thicknesses or products for fire-rated systems.*
#### External Sheathing (Render Carrier)
For render-finished steel frame facades:
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Steel stud frame
→ Mineral wool or PIR insulation
→ Terasun TSM 12 mm (direct fix to studs)
→ Fibreglass mesh tape at joints
→ Alkali-resistant fibreglass mesh bedded in basecoat
→ Mineral or silicone render finish
``
Fiber cement board provides an excellent render substrate — it does not absorb excessive render moisture, is dimensionally stable, and does not transfer organic contamination to the render surface.
Fixing Specification
| Board thickness | Screw type | Screw length | Fixing centres |
|---|---|---|---|
| 8 mm | A4 s/s self-drilling | 38 mm | 200 mm perimeter / 300 mm field |
| 10 mm | A4 s/s self-drilling | 45 mm | 200 mm perimeter / 300 mm field |
| 12 mm | A4 s/s self-drilling | 50–55 mm | 200 mm perimeter / 300 mm field |
All fixings should penetrate the steel stud by a minimum of 15 mm. Use A4 (marine grade) stainless steel in all exterior and wet applications.
Ordering and Specification Data
Standard format: 1,220 × 2,440 mm Available thicknesses: 6, 8, 10, 12, 15, 18 mm CE marking: 1023-CPR-1565 P (EN 12467) ETA: 24/0895 Weight (12 mm): 9.96 kg/m² Minimum order: approx. 1,600–2,200 m² (20ft container), smaller quantities from Finnish warehouse
Downloads
- Technical Data Sheet (TDS)
- Installation Guide
- CE Certificate 1023-CPR-1565 P
- ETA 24/0895
- Fire Test Report FIRES-CR-284-25-AUPE
- DoP TRS-20250610F
All available from the Terasun Europe document library.
*Terasun Europe is not the manufacturer of Terasun products. Terasun Europe acts as the Authorised European Representative for Zhejiang Terasun Air Duct Co., Ltd., Zhejiang Province, China.*
Frequently asked questions
What stud spacing can be used with Terasun TSM fiber cement board?
Terasun TSM board can be fixed to steel studs at 400 mm or 600 mm centres. For 8 mm board on 600 mm centres, verify deflection against the technical data sheet. For 10–12 mm board, 600 mm centres are standard for exterior facade applications.
Can fiber cement board form part of a fire-rated steel frame wall?
Yes. The tested wall assembly using 12 mm Terasun TSM boards on steel studs with mineral wool infill achieves E 120 / EI 90 / EW 120 (fire test FIRES-CR-284-25-AUPE). The fire classification applies to the tested assembly, not the board alone.
What screws should be used to fix fiber cement board to steel studs?
Use A4 (marine grade) stainless steel self-drilling screws. Length depends on board thickness — for 12 mm board, use 50–55 mm screws. Pre-drill the board at 3 mm diameter. Minimum penetration into steel stud: 15 mm.