Key takeaways
- Fiber cement's difficulty is on site; metal's difficulty is in the specification.
- Cutting fiber cement is a regulated silica exposure with prescribed controls.
- For composite metal panels, fire compliance belongs to the tested assembly, not the panel.
- Thermal movement constrains metal panel size in a way it does not constrain fiber cement.
At a glance
| Criterion | Fiber Cement Cladding | Metal Wall Panels |
|---|---|---|
| Product standard | ASTM C1186 for flat sheets used as cladding, facades and soffits | No single product standard; systems differ, and fire is assembly-level |
| Fire compliance route | Cement-based; classification still belongs to the tested assembly | NFPA 285 on the complete assembly; core material is decisive for composites |
| Site hazard | Cutting releases respirable crystalline silica; controls are prescribed | Cutting and handling hazards are conventional for sheet metal |
| Thermal movement | Modest for a cement-based board | Significant; constrains panel size, span and fixing |
| Finish and maintenance | Site-finished product enters a repainting cycle; factory-finished does not | Coating warranty is separate from the panel warranty |
| Damage in service | Brittle at edges; chips rather than dents | Dents and oil-cans; damage is visible and hard to repair invisibly |
| Substitution risk | Low | High — changing insulation or cavity can leave a tested assembly |
The decision in one paragraph
These two fail at opposite ends of the process. Fiber cement is easy to specify and demanding to cut safely. Metal is straightforward on site and demanding to specify, because for composite panels the fire question belongs to the entire wall assembly rather than to the panel you selected.
Where each one’s difficulty lives
Fiber cement’s difficulty is on site. The material contains crystalline silica, and cutting it with a power saw generates respirable dust. NIOSH sets a recommended exposure limit of 0.05 mg/m³ and has measured uncontrolled cutting at up to 3.4 times that level. OSHA prescribes a specific control for handheld saws with blades of 8 in or less; NIOSH found a shop vacuum on the saw brought levels well below the limit. This is manageable, but it has to be planned rather than discovered.
Metal’s difficulty is in the specification. NFPA 285 evaluates the complete exterior wall assembly — insulation, cavity depth, water-resistive barrier, attachment and joints all influence the result. A manufacturer’s listing applies to the configurations that were tested, so substituting insulation or changing the cavity can put the wall outside it while the panel stays the same.
For composite panels the core decides the range of achievable assemblies: polyethylene core does not pass and is restricted above 40 ft on Type I and II buildings; fire-retardant core can pass as part of a compliant assembly; mineral core passes across the widest range.
Thermal movement separates them physically
Metal moves more. Panel size, span and fixing type all have to accommodate it, and the visible consequences — oil-canning, fastener distress — appear on the finished wall. Fiber cement’s movement is modest by comparison, which is part of why it tolerates simpler fixing.
Maintenance is a choice you make at specification
Fiber cement supplied primed enters a repainting cycle set by the coating. Supplied factory-finished, it does not. Metal panels carry a coating warranty that is separate from the panel warranty and worth reading separately.
Neither is maintenance-free, and the honest comparison is between two different cycles rather than between maintenance and none.
Which one should you choose?
Choose fiber cement on buildings where NFPA 285 does not apply, where the budget favours material cost over specification effort, and where cutting can be controlled properly.
Choose metal where large formats, long spans or precise lines matter, where a rainscreen is wanted, and where the project can carry the assembly-level compliance work.
On a high-rise where NFPA 285 applies, the metal route is an assembly exercise from the start. That is usually what decides it.
Read the full material guides
Fiber Cement Cladding and Metal Wall Panels cover each in full, or see how both compare in our overview of materials for exterior walls. For the rest of the family, browse wall cladding.
Frequently asked questions
Which is cheaper?
Fiber cement is generally the lower material cost, but the comparison changes once a site-finishing cycle or an NFPA 285 assembly is priced. Compare installed cost including finishing and compliance work rather than board or panel price.
Is metal cladding a fire risk?
The metal is not. For composite panels the core is what matters: polyethylene core is combustible and does not pass NFPA 285, while mineral core passes across the widest range of assemblies. And the test applies to the whole wall, so the panel alone never settles it.
Sources
- ASTM C1186 — Standard Specification for Flat Fiber-Cement Sheets — ASTM International Accessed August 28, 2026.
- OSHA's Respirable Crystalline Silica Standard for Construction — OSHA Accessed August 28, 2026.
- NFPA 285 — Standard Fire Test Method for Exterior Wall Assemblies (scope) — National Fire Protection Association Accessed August 28, 2026.