Introduction
Metal flashings are an essential component in modern roofing and wall cladding systems, serving both functional and aesthetic purposes. They are designed to prevent water ingress at critical junctions, ensuring buildings remain weather-resistant while also contributing to a polished architectural finish. Lysaght produces a range of high-quality flashings made from 100% Australian steel including COLORBOND® steel and ZINCALUME® steel. These flashing products are specifically engineered to integrate seamlessly with our comprehensive range of roofing and walling products.
This article explores the purpose of flashings, the materials they are made from, the various types available, as well as key design and installation practices that ensure their optimal performance.
Understanding Flashings and Their Role
Flashings are strips of metal that are accurately formed and shaped to protect the edges, joints, and intersections of a roof or wall structure. Their primary role is to divert water away from vulnerable areas, reducing the risk of leaks and structural deterioration. By covering the gaps between roofing, walling and other building elements, flashings not only enhance a building’s durability but also improve its overall visual appeal.
When properly installed, flashings create a reliable barrier that prevents water from penetrating the building envelope. They are commonly placed at:
- Ridges
- Valleys
- Parapets
- Around wall penetrations such as windows and doors, as well as roof penetrations such as air-conditioning units, skylights and ventilation systems.
Without them, water could easily seep into the structure, leading to potentially extensive damage that can be costly to repair.
Materials Used in Flashing Manufacturing
LYSAGHT® flashings are manufactured from a selection of robust materials, each chosen for its specific performance attributes. These include:
- COLORBOND® steel – Known for its superior durability, colour retention, and corrosion resistance.
- ZINCALUME® steel – A high-strength, corrosion-resistant material with a sleek metallic finish.
- Galvanised steel – Coated with a layer of zinc to provide additional corrosion protection, making it ideal for harsh weather conditions.
- Aluminium – Lightweight and highly resistant to corrosion, particularly in coastal or industrial environments.
- Stainless steel – Typically ASTM Type 430, providing an additional option for aggressive environments
Copper and lead flashing can also sometimes be used for specific applications.
Care does need to be taken when choosing flashing materials to ensure they are compatible with surrounding building components. For more information refer to Lysaght Product Advisory Bulleting PAB02 – Metal and Timber Compatibility.
Types of Flashings and Their Applications
Flashings come in a variety of forms, each designed for specific structural needs. Some of the most common types include:
- Ridge or Hip Capping – Used along the top ridge where two roof planes meet, providing both weatherproofing and a seamless appearance.
- Apron Flashing – Positioned at the junction between a roof and a vertical surface, such as a wall or chimney, to direct water away.
- Valley Gutters – Installed where two opposing roof slopes converge, ensuring rainwater is effectively channelled towards the main drainage system.
- Barge Capping – Provides a weatherproof and aesthetically pleasing finish to the gable ends of a roof.
- Box Gutters – Typically concealed within a roof structure, designed to handle large volumes of water, often placed behind parapet walls.
- Parapet Capping – Prevents water from penetrating the tops of parapet walls.
- Corner Flashings – Used at wall intersections to enhance weather resistance.
Tapered and Curved Flashings – Customised for unique architectural applications such as bullnose roofing.
Best Practices for Flashing Design and Installation
To ensure the effectiveness and longevity of flashings, several key principles must be followed:
- Accurate Measurement and Ordering
- Determine precise dimensions, including angles and bends, for a proper fit.
- Specify the correct material and finish to match the project’s requirements.
- Reference the LYSAGHT® price book or standard flashing drawings.
- Proper Overlaps and Sealing
- Ensure overlaps are positioned in the direction of water flow.
- Maintain a minimum overlap of 150mm for longitudinal flashings.
- Notch or scribe transverse flashings to fit over the ribs of the roofing material.
- Apply appropriate (neutral-cure) sealants to prevent capillary action from drawing water into joints.
- Fixing and Support
- Secure flashings at intervals of no more than 500mm.
- Use screws instead of rivets for greater shear capacity and stronger hold.
- Comply with AS/NZS 1562.1 to ensure proper support spacing.
- Thermal Expansion Considerations
- Install expansion joints for flashings exceeding 12 metres in length.
- Maintain a gap of 2-5mm at horizontal surfaces to prevent moisture retention.
- Wind and Weather Resistance
- Securely fasten flashings to withstand wind pressures.
- Use additional fastening and bracing in cyclone-prone areas.
Ordering Flashings
Ordering the correct flashings requires precise attention to detail. To ensure a smooth ordering process, you’ll need to provide the following key information:
- Profile Type – Identify the flashing profile needed, referencing standard drawings and codes from the LYSAGHT® price book. Alternatively, you can provide a diagram of the flashing shape you need.
- Material Finish – Specify whether the flashing should be manufactured from COLORBOND® steel, ZINCALUME® steel, or another material.
- Colour Side – Indicate which side of the sheet should display the colour, ensuring it aligns with the building’s aesthetics.
- Dimensions – Provide accurate measurements, including the width (girth) of the flashing, along with all relevant angles and bends.
- Quantity and Lengths – Specify the number of flashings required and their respective lengths.
For custom flashings, additional details such as special bends or crush folds should be clearly communicated. If there are any uncertainties regarding the order, it is advisable to consult with a Lysaght representative to avoid errors and ensure a precise fit.
Additional Accessories and Enhancements
In addition to flashings, Lysaght offers a range of accessories to improve performance and facilitate installation:
- Dektites – Flexible rubber flashings for sealing around pipe penetrations.
- Spear Points – Fixing accessories that enhance the security of installed flashings.
- Edge or Gable Rolls – Additional support for barge capping, ensuring a cleaner and more durable finish.
- Adjustable Box Gutter Brackets – Helps maintain proper drainage and structural integrity in box gutter systems.
Conclusion
Flashings are a vital element in roofing and walling systems, contributing to durability, weatherproofing, and overall aesthetic appeal. With a wide variety of standard and custom flashings available, Lysaght provides solutions tailored to meet the diverse needs of builders and architects. By adhering to best practices in design and installation, professionals can ensure their projects achieve both long-lasting performance and visual excellence.
For further information on LYSAGHT® flashings, visit lysaght.com or talk to a Lysaght representative.