A flashing profile that is suitable for one project is not automatically the right choice for another.
Consider three buildings. One is a coastal home exposed to salt-laden air. Another is an industrial facility where airborne contaminants may be present. The third sits on an elevated, open site where strong winds regularly drive rain against the roof and wall junctions.
The folds may look similar on a drawing, but the surrounding environment can influence the appropriate material, finish, detailing and maintenance requirements.
Start with the building environment
Colour is important to the finished appearance, but it should not be the first or only consideration when selecting custom flashings.
The project team should first consider what the flashing is likely to encounter throughout its service life.
Questions worth answering include:
- How close is the building to the coastline?
- Is it exposed to breaking surf or calm marine water?
- Are industrial emissions or airborne contaminants present?
- Does wind regularly drive rain against the junction?
- Can salt, moisture, dirt or debris collect on the flashing?
- What materials will sit above or beside it?
- Will the area be naturally washed by rain?
- Can the flashing be safely accessed for future inspection?
The answers provide useful context for the architect, builder, roof plumber, product manufacturer and fabricator.
Coastal exposure is not the same everywhere
A protected building near calm water does not experience the same conditions as a roof close to breaking surf.
BlueScope’s official steel grade guide divides marine environments into different exposure categories. It identifies COLORBOND® Ultra steel as its recommended roofing product for severe marine environments, described as approximately 100 to 200 metres from breaking surf or up to 100 metres from calm marine water.
These distances are guidance rather than a complete project specification. BlueScope notes that local conditions, prevailing winds and unwashed areas can influence performance.
The application also matters. A roof surface regularly washed by rain experiences different conditions from the underside of a flashing, a sheltered wall junction or an area where salt and debris can accumulate.
Industrial sites require project-specific consideration
The term industrial covers many different environments.
A storage warehouse may present relatively mild conditions. A manufacturing or processing site could expose building materials to heavy fallout, acids, alkaline substances or other corrosive chemicals.
BlueScope’s grade guidance states that COLORBOND® steel is suitable for light industrial environments but recommends seeking specific advice where heavy industrial fallout or corrosive chemicals are present.
The project team should understand what occurs inside and around the building, including what substances may enter the air or settle on roof and wall components.
The right solution cannot be determined by the building’s industrial zoning alone.
Check adjoining materials
A flashing can be accurately folded and correctly positioned but still face a problem if incompatible materials have been combined within the detail.
BlueScope’s guidance on compatible metals warns that copper and lead can contribute to accelerated corrosion when placed in direct contact with COLORBOND® steel. Water should not be directed from copper components onto COLORBOND® steel either.
Run-off can be just as important as direct contact. The project team should consider what sits upstream from the flashing and where water will travel after leaving it.
Fixings, sealants and support materials should also be checked against the relevant specifications.
High exposure changes more than the profile width
Elevated and open sites may experience stronger winds and more persistent wind-driven rain than sheltered locations.
Building height, roof shape, orientation and surrounding terrain can all affect the conditions at a particular junction.
The solution is not necessarily to make every flashing larger. Coverage, support, fixings, laps, joints and the adjoining roofing or cladding system need to be considered together.
Long exposed runs may also require more planning around joint positions and movement. Complex corners and changes of direction are better resolved through drawings before fabrication than improvised after delivery.
Consider future maintenance
Areas naturally washed by rain may require less cleaning than sheltered surfaces. BlueScope’s maintenance guidance recommends regular washing of unwashed areas and more frequent attention in locations affected by marine salt spray or high industrial fallout.
Designing out places where water and debris can sit may make future maintenance easier, particularly where safe access will be difficult.
Give the fabricator the full picture
The order should identify the application, location, material, finish and any relevant specification prepared by the architect, engineer or product manufacturer.
Site photographs can also provide useful context where the flashing meets roofing, masonry, cladding or another metal component.
PPC Flashings manufactures custom flashings and roofing accessories for projects across Melbourne and Victoria. Where a site presents unusual coastal, industrial or weather exposure, sharing the project specifications and environmental context before fabrication can help identify questions while there is still time to resolve them.
The information contained in this news post is provided by way of general information only and has not been prepared with your specific needs in mind. Before application in a particular situation, we recommend that you obtain expert advice confirming the suitability of the services and/or products and information in question for the application proposed.