Steel or aluminium? Specify your roof terrace with confidence.
A free 5-minute guide comparing the two leading roof terrace substructures on fire performance, load capacity, spans, membrane protection and compliance.
5 min read · No sign-up required
The decisions that carry the most risk
The substructure decides how your terrace performs under load, how the programme runs, and whether it satisfies Building Safety Act fire requirements. The guide breaks down where each system wins.
Fire performance
Both can be non-combustible, but they behave very differently in fire. Steel holds strength to ~1,370°C; aluminium melts at ~660°C.
Load & spans
Steel carries heavier finishes over longer spans with fewer supports. Aluminium is typically limited to ~600mm between pedestals.
Membrane protection
Neither penetrates the waterproofing. The difference is how load reaches the membrane, and what that means at height.
A side-by-side you can specify from
The full guide compares ten criteria across both systems, then closes with a specifier's checklist you can take straight into your next project.
See the full comparison| Criterion | Steel Frame | Aluminium Rail & Pedestal |
|---|---|---|
| Fire, structural | Holds strength to ~1,370°C+ | Softens; melts ~660°C |
| Load capacity | High | Moderate |
| Spans | Long, fewer supports | ~600mm max |
| Best suited to | Large, high, heavily loaded | Small, simple, light loads |
A specifier's checklist, built in
- Building height — over 11m? Confirm A2-s1,d0 or A1 classification.
- Imposed loads — planters, furniture, hot tubs and footfall accounted for.
- Spans vs limits — within the system's maximum span.
- Point loads — checked against membrane compressive limits.
- Wind uplift — exposure at height assessed and fixing chosen.
Steel Frame vs Aluminium Rail-and-Pedestal
Roof terrace substructures compared.
Send us your drawings for a no-obligation proposal
A compliant, pre-engineered galvanised steel substructure with technical support from design to handover, and finishes from porcelain and stone to artificial grass.
Steel or aluminium? Specify your roof terrace with confidence.
A free 5-minute guide comparing the two leading roof terrace substructures on fire performance, load capacity, spans, membrane protection and compliance.
5 min read · No sign-up required
The decisions that carry the most risk
The substructure decides how your terrace performs under load, how the programme runs, and whether it satisfies Building Safety Act fire requirements. The guide breaks down where each system wins.
Fire performance
Both can be non-combustible, but they behave very differently in fire. Steel holds strength to ~1,370°C; aluminium melts at ~660°C.
Load & spans
Steel carries heavier finishes over longer spans with fewer supports. Aluminium is typically limited to ~600mm between pedestals.
Membrane protection
Neither penetrates the waterproofing. The difference is how load reaches the membrane, and what that means at height.
A side-by-side you can specify from
The full guide compares ten criteria across both systems, then closes with a specifier's checklist you can take straight into your next project.
See the full comparison| Criterion | Steel Frame | Aluminium Rail & Pedestal |
|---|---|---|
| Fire, structural | Holds strength to ~1,370°C+ | Softens; melts ~660°C |
| Load capacity | High | Moderate |
| Spans | Long, fewer supports | ~600mm max |
| Best suited to | Large, high, heavily loaded | Small, simple, light loads |
A specifier's checklist, built in
- Building height — over 11m? Confirm A2-s1,d0 or A1 classification.
- Imposed loads — planters, furniture, hot tubs and footfall accounted for.
- Spans vs limits — within the system's maximum span.
- Point loads — checked against membrane compressive limits.
- Wind uplift — exposure at height assessed and fixing chosen.
Steel Frame vs Aluminium Rail-and-Pedestal
Roof terrace substructures compared.
Send us your drawings for a no-obligation proposal
A compliant, pre-engineered galvanised steel substructure with technical support from design to handover, and finishes from porcelain and stone to artificial grass.