.48 BMT TRIMDEK® COLORBOND® Roofing Sheets

0.48 BMT LYSAGHT® TRIMDEK® COLORBOND® Roofing Sheets

0.48 BMT LYSAGHT® TRIMDEK® is the thicker COLORBOND® steel option for roofing and wall cladding where the project design specifies 0.48 BMT instead of .42 BMT. It retains TRIMDEK®’s lightweight and economical five-rib profile, with bold trapezoidal ribs, subtle fluting and a peak detail through each pan for a clean, structured appearance.

Manufactured from genuine BlueScope COLORBOND® G550 steel, the 0.48 BMT profile has higher published maximum support spacings than .42 BMT under the conditions stated in the LYSAGHT® technical guide. This can benefit correctly designed residential, commercial and industrial projects, but 0.48 BMT does not automatically make a roof suitable for every wider span, exposed site or wind classification.

What Does BMT Mean and Why Is 0.48 BMT Significant?

BMT means Base Metal Thickness, which is the thickness of the steel before its protective metallic and painted coatings are applied. A 0.48 BMT sheet is thicker than a .42 BMT sheet and has different tested design capacities.

The LYSAGHT® guide lists 0.48 BMT COLORBOND® TRIMDEK® at approximately 3.76kg per lineal metre, compared with 3.32kg per lineal metre for .42 BMT. Both provide a nominal cover width of 762mm. The correct thickness must be selected alongside the span arrangement, support material, fasteners, wind pressures and complete building design. If the project documentation specifies .42 BMT, moving to 0.48 BMT may add cost without providing a necessary benefit.

Why Choose 0.48 BMT TRIMDEK®?

Choose 0.48 BMT when it is specified in the building design or when the required design capacities fall outside the appropriate .42 BMT limits. The thicker steel provides increased rigidity and higher published maximum support spacings than .42 BMT under the conditions stated in the LYSAGHT® technical guide.

TRIMDEK® remains a lightweight and economical profile for versatile roof and wall cladding applications. Its strength, lightness, rigidity and remarkable recovery after deformation can assist maintenance requirements, while the bold trapezoidal ribs and subtle peak detail provide a clean, pleasing finish.

Published Maximum Support Spacings for 0.48 BMT TRIMDEK® Roofing

These are published maximum values, not project-specific design instructions. The LYSAGHT® guide applies stated assumptions, including non-cyclonic conditions, wind-pressure criteria and minimum support requirements. Serviceability, strength, wind pressure, fasteners, support material and other project conditions may require smaller spacings. Have the applicable spacing confirmed from the complete project design.

Common applications include:

• Residential, commercial and industrial projects where 0.48 BMT is specified

• Roofing and wall cladding requiring the published 0.48 BMT design capacities

• Long roof runs where custom sheet lengths can help reduce end laps

• Replacement projects that must match an existing 0.48 BMT specification

• Projects where the approved support arrangement requires the thicker TRIMDEK® option

The correct COLORBOND® product grade must also be selected for the site environment. Choosing 0.48 BMT does not by itself provide additional corrosion protection or make standard COLORBOND® steel suitable for every coastal or industrial location.

Profile, Cover Width and Custom Lengths

TRIMDEK® features a distinctive 5-rib profile with a 762mm cover width and a rib height of approximately 29mm. This structured appearance is popular among builders and homeowners. COLORBOND® Matt TRIMDEK® roofing and walling sheets offer an alternative finish for projects focused on architectural aesthetics.

TRIMDEK® is available in long lengths, allowing many jobs to use a single sheet from ridge to gutter without end laps. Sheets are supplied custom cut, which helps reduce waste and makes it easier to order the exact length for your project.

Designed for Low Roof Pitches

One of TRIMDEK®'s biggest advantages is its suitability for low roof pitches. Per the supplier guide, TRIMDEK® cladding can be used on roof pitches as low as 2° (1 in 30) thanks to its long sheet lengths and anti-capillary groove. This makes it a practical choice for modern roof designs where low-slope roofing is part of the aesthetic or engineering brief.

Made from Genuine COLORBOND® Steel

These .48 BMT TRIMDEK® sheets are manufactured from genuine COLORBOND® steel, delivering the proven durability, corrosion resistance and finish consistency expected from BlueScope products. See other COLORBOND® roofing sheets for Australian conditions. COLORBOND® steel complies with AS/NZS 2728 and uses an aluminium/zinc alloy-coated steel base complying with AS 1397. Core COLORBOND® colours in Classic and Matt finishes include Thermatech® solar reflectance technology.

Installation and Roof System Compatibility

Fixing methods: TRIMDEK® is a pierce-fixed roofing profile and can be fixed to timber or steel supports. Following recommended COLORBOND® TRIMDEK® installation methods helps ensure long-term performance. For roofs, screws should be placed through the crests to maximise watertightness, and sheets typically overlap into gutters by around 50mm. On very low slopes, additional detailing may be required to control capillary action.

System integration: This profile is designed to integrate neatly with compatible TRIMDEK® ridge capping and flashings, gutters, downpipes and fasteners, and with complementary COLORBOND® flat sheet roof flashing.

Accessory compatibility: If you're ordering roofing sheets online, it makes sense to add matching ridge capping, barge capping, screws, insulation and rainwater goods at the same time. Consider whether you also need COLORBOND® flat sheets in wide 1200mm sizes for custom flashings or infill panels.

Why Buy .48 BMT Instead of .42 BMT?

For straightforward standard residential jobs, .42 BMT may be enough. Some industrial or coastal projects may benefit from ZINCALUME® TRIMDEK® roofing sheets in .48 BMT for extra corrosion protection.

If you need more strength, better spanning ability, or a stronger sheet for demanding conditions, .48 BMT TRIMDEK® is the better choice - alongside other low-pitch options like COLORBOND® KLIP-LOK® 700. Same recognisable TRIMDEK® profile and COLORBOND® finish, with extra thickness and a more heavy-duty feel on the roof.

Order TRIMDEK® .48 BMT Cut to Your Required Length

At Metal Roofing Online, order .48 BMT TRIMDEK® COLORBOND® roofing sheets online in your selected colour and required length. Easy to price your roof, reduce waste and get the stronger sheet when your project calls for it. Comparing alternative profiles? See COLORBOND® standing seam cladding.

If you're comparing TRIMDEK® options, this page is the right choice when you want the 0.48 BMT version - not the lighter .42 BMT alternative.

0.48 BMT vs .42 BMT TRIMDEK®

Both thicknesses use the same recognisable TRIMDEK® profile, with a 762mm nominal cover width, 29mm rib height and minimum roof pitch of 2°. The difference is the thickness, mass and published design capacities of the steel.

The support-spacing figures are published maxima under the assumptions stated in the LYSAGHT® guide. They are not a substitute for the project’s structural and wind design.

For many standard residential projects, .42 BMT COLORBOND® TRIMDEK® may satisfy the building requirements. Choose 0.48 BMT when the project documentation specifies it or when the approved design requires its different tested capacities. Residential, commercial and industrial labels alone do not determine the correct thickness.

BMT also does not determine corrosion suitability. The correct COLORBOND® product grade must be selected for the site’s distance from breaking surf, industrial exposure and other environmental conditions.

Order 0.48 BMT TRIMDEK® Cut to Length

Order 0.48 BMT COLORBOND® TRIMDEK® roofing and wall cladding online in your selected colour and required length. Each sheet is custom cut after ordering, helping reduce unnecessary joins, end laps and on-site waste.

Select your delivery state first to view the available colours and pricing. Enter the required length and quantity, then add each different sheet length as a separate line item. Check all measurements carefully before ordering because the sheets are manufactured specifically for your project.

Frequently Asked Questions

What does BMT mean?

BMT means Base Metal Thickness. It is the thickness of the steel before the protective metallic and painted coatings are applied. A 0.48 BMT sheet is thicker and heavier than a .42 BMT sheet.

What is the main advantage of 0.48 BMT TRIMDEK®?

The 0.48 BMT option has different tested design capacities and higher published maximum support spacings than .42 BMT under the conditions stated in the LYSAGHT® guide. It is suitable when those capacities are required by the approved project design.

Is 0.48 BMT automatically suitable for higher wind zones?

No. BMT alone does not establish wind suitability. The roof or wall system must be assessed using the applicable wind pressures, span arrangement, supports, fastener type, fastener quantity and other project conditions. Cyclonic applications require the relevant cyclonic design information.

Is 0.48 BMT only used for commercial roofing?

No. It can be used for residential buildings, commercial roofing, industrial buildings and wall cladding. The correct thickness is determined by the project design, not the building label.

What is the minimum roof pitch for TRIMDEK®?

The published minimum roof pitch is 2°, or 1 in 30. The completed roof must maintain this minimum after allowing for construction tolerances and deflection. Low-pitch roofs must also follow the applicable drainage, sheet-end and installation requirements.

Does thicker 0.48 BMT steel improve thermal performance?

BMT is primarily a structural specification and is not a substitute for roof insulation. Thermal performance depends on the complete roof system, including the selected COLORBOND® colour, insulation, sarking, ventilation and building design.

Which COLORBOND® colours are available?

Availability varies by product and delivery location. Options may include Classic Cream™, Woodland Grey®, Deep Ocean®, Pale Eucalypt®, Evening Haze® and Manor Red®, along with other colours shown after selecting your state. Confirm availability before finalising the roof colour scheme.

Are the sheets supplied cut to length?

Yes. Sheets are custom cut to the required length selected when ordering, up to the available delivery limit shown on the page. LYSAGHT® publishes a length tolerance of +0mm / -15mm and a width tolerance of +4mm / -4mm.

Are end laps or expansion joints required?

Long sheet lengths allow many roofs to run from ridge to gutter without end laps. Whether end laps or expansion joints are required depends on the roof length and design. Obtain the correct LYSAGHT® detail before ordering or installing any joint.

What accessories are required?

Requirements vary by project but may include compatible roofing screws, ridge capping, barge capping, other flashings, insulation, gutters, fascia and downpipes. Correct accessories and installation are required to create a weather-resistant roof system.