Repair Systems — 04 — Roofing Defects
Trimdek sheet replacement systems
Trimdek is a high-rib trapezoidal steel roofing sheet with a 35mm rib height and 762mm cover width, widely used on Australian commercial and Class 2 strata buildings for its structural performance and flat-pan appearance. Replacement requires matching the trapezoidal profile exactly — Trimdek is not interchangeable with corrugated sheet or concealed-fix profiles.
What is Trimdek sheet replacement?
Trimdek is a high-rib trapezoidal steel roofing sheet with a 29mm rib height and 762mm cover width, specified for its strong structural performance and clean flat-pan appearance. Unlike the sinusoidal corrugated profile, Trimdek's wider flat pans and high ribs at 200mm centres allow greater purlin spacing and span capability at equivalent BMT. Sheet replacement requires matching the profile exactly — Trimdek is not interchangeable with corrugated sheet or concealed-fix profiles.
Technical Reference
BMT selection, pan-fixing requirements, minimum pitch and colour matching guidance
Product Reference
3 products — 3 brands — trapezoidal Colorbond steel sheet systems
Lysaght Trimdek
High-rib trapezoidal Colorbond steel sheet; 29mm rib height; 762mm cover width; pan-fixed; AS 1562.1 compliant
Product type
Trapezoidal Colorbond steel sheet — 762mm cover — AS 1562.1
System description
Lysaght Trimdek is the Australian market's primary high-rib trapezoidal steel roofing sheet. The profile features a distinctive flat pan flanked by high ribs at 200mm centres, producing a strong structural profile suited to longer purlin spans than corrugated sheet at equivalent BMT. Trimdek is through-fixed via screws driven through the pan (not the rib) into the purlin below, with an EPDM or neoprene sealing washer compressing against the pan face to maintain weathertightness. The full Colorbond colour range is available. It is the most widely specified trapezoidal product on Australian Class 2 strata and commercial flat-to-low-pitch roofs.
Technical properties
- Profile: trapezoidal (high-rib), 29mm rib height, 200mm rib pitch
- Cover width: 762mm per sheet (5 pans per sheet)
- BMT: 0.42mm (standard residential), 0.48mm (Class 2/commercial), 0.60mm, 0.70mm
- Substrate: BlueScope Colorbond steel — full Colorbond colour range
- AS 1562.1 compliant — design wind pressures confirmed against span tables
- Pan-fixed: screws through pan (not rib) into purlins; EPDM sealing washers required
- Minimum pitch: 5° (Lysaght recommended); consult TDS for low-pitch applications
- Not suitable for walking without duckboards — pan deformation risk
Limitations
- Profile is NOT interchangeable with corrugated sheet — different rib spacing, fixing and span tables
- Pan-fixed screw holes must align with purlin spacings — existing purlin layout must be checked before specifying
- Colorbond colour must match existing or obtain strata committee approval for variation
- BMT must be confirmed against AS 1562.1 wind pressure tables by a structural engineer for Class 2 buildings
- Not designed for traffic without duckboards or temporary protection
Procurement
Lysaght branches and authorised Lysaght distributors nationally. BlueScope Steel distribution centres. Available to trade through major roofing merchants.
View TDS / product pageConfirm suitability with the current manufacturer TDS before specifying or applying.
Stramit TrimClad
High-rib trapezoidal Colorbond steel sheet; equivalent profile to Trimdek; 762mm cover; pan-fixed; AS 1562.1 compliant
Product type
Trapezoidal Colorbond steel sheet — 762mm cover — AS 1562.1
System description
Stramit TrimClad is Stramit's high-rib trapezoidal steel roofing sheet, dimensionally equivalent to Lysaght Trimdek at 762mm cover width and 29mm rib height. Manufactured from BlueScope Colorbond steel and available in the full Colorbond colour range. Pan-fixed via screw through pan into purlin. Stramit's national branch network provides supply in all major Australian markets and the product is widely used as a like-for-like replacement for Trimdek on existing trapezoidal metal roofs. Confirm current product specifications and span tables against the current Stramit TDS.
Technical properties
- Profile: trapezoidal (high-rib), 29mm rib height, 762mm cover width
- BMT: 0.42mm, 0.48mm standard; confirm availability for 0.60mm and 0.70mm with Stramit
- Substrate: BlueScope Colorbond steel — full Colorbond colour range
- AS 1562.1 compliant — Stramit span tables published in current TDS
- Pan-fixed: screws through pan into purlins with EPDM sealing washers
- Dimensionally interchangeable with Lysaght Trimdek for replacement work
Limitations
- Confirm current product name and specs from Stramit TDS — product names subject to change
- Span and load tables are Stramit-specific — do not cross-reference with Lysaght tables
- Local branch availability should be confirmed before specifying as replacement
Procurement
Stramit branches nationally (Adelaide, Brisbane, Melbourne, Perth, Sydney and regional). Major roofing steel distributors and merchants.
Confirm suitability with the current manufacturer TDS before specifying or applying.
Stratco Coverline
Trapezoidal Colorbond steel roofing sheet; equivalent high-rib profile; 762mm cover; pan-fixed; AS 1562.1 compliant
Product type
Trapezoidal Colorbond steel sheet — 762mm cover — AS 1562.1
System description
Stratco supplies trapezoidal Colorbond steel roofing sheets through their branch network as a supply alternative to Lysaght and Stramit. Products are manufactured from BlueScope Colorbond steel and are dimensionally compatible with the standard high-rib trapezoidal profile for replacement work. Confirm the current Stratco product name, cover width, BMT options and span tables from the Stratco technical data sheet before specifying — product naming conventions may differ from Lysaght and Stramit.
Technical properties
- Profile: high-rib trapezoidal — confirm exact rib height and pitch from Stratco TDS
- Cover width: 762mm — confirm with current Stratco TDS
- Substrate: BlueScope Colorbond steel — full Colorbond colour range
- BMT: 0.42mm standard — confirm additional BMT options from Stratco
- AS 1562.1 compliant
Limitations
- Confirm current product name from Stratco — naming convention differs from Lysaght and Stramit
- Stratco span tables must be used for Stratco product; do not cross-reference with Lysaght tables
- Less widely distributed than Lysaght and Stramit in some states — confirm local branch availability
Procurement
Stratco branches nationally (major capital cities and regional centres). Direct supply to trade.
Confirm suitability with the current manufacturer TDS before specifying or applying.
Brand Equivalence
All three products share the same trapezoidal profile and BlueScope Colorbond substrate. Selection is driven by supply channel and local availability.
| Product A | Product B | Equivalence note |
|---|---|---|
| Lysaght Trimdek | Stramit TrimClad | Dimensionally equivalent — same 762mm cover, 29mm rib height, BlueScope Colorbond substrate. Pan-fixed with same screw pattern. Product name differs; span tables are manufacturer-specific. |
| Lysaght Trimdek | Stratco (trapezoidal) | Dimensionally compatible for replacement work on existing trapezoidal roofs. Confirm current Stratco product name and TDS before specifying — naming may differ from Lysaght. |
| Stramit TrimClad | Stratco (trapezoidal) | All three products use BlueScope Colorbond steel and the same colour range. Selection is driven by supply channel and local branch availability. |
System Comparison
Side-by-side comparison of trapezoidal Colorbond sheet products. Confirm all selections against the current manufacturer TDS before specifying.
| Attribute | Lysaght Trimdek | Stramit TrimClad | Stratco (trapezoidal) |
|---|---|---|---|
| Profile | High-rib trapezoidal | High-rib trapezoidal | High-rib trapezoidal |
| Cover width | 762mm | 762mm | 762mm (confirm TDS) |
| Rib height | 29mm | 29mm | Confirm TDS |
| BMT standard | 0.42mm / 0.48mm | 0.42mm / 0.48mm | 0.42mm (confirm options) |
| Substrate | BlueScope Colorbond | BlueScope Colorbond | BlueScope Colorbond |
| Fixing type | Pan-fixed (screw/washer) | Pan-fixed (screw/washer) | Pan-fixed (confirm) |
| Colour range | Full Colorbond range | Full Colorbond range | Full Colorbond range |
| AS 1562.1 | Compliant | Compliant | Compliant |
Do not confuse Trimdek with:
- Corrugated sheet (Custom Orb / Stramit Corrugated) — a sinusoidal profile with 76mm corrugation pitch and 762mm cover. Not interchangeable with Trimdek — different profile, different fixing pattern, different span tables.
- Klip-Lok (concealed fix) — a concealed clip system with no through-fasteners in the field. Completely different fixing mechanism to Trimdek. Requires different substructure, installer competency and minimum pitch.
- Zincalume Trimdek — the same trapezoidal profile but with an unpainted AZ150 zinc-aluminium substrate rather than a Colorbond painted finish. Not a like-for-like substitute where a painted finish is required or specified.
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, substrate condition, roof pitch, wind classification, AS 1562.1 requirements, structural engineer sign-off, and installer warranty conditions. Do not rely on this reference as a substitute for professional engineering or roofing consultant advice.