Why use solar roof flashing rather than standard metal flashing? It’s a question sometimes still asked at a plumber’s wholesale counter.
Choosing the right roof flashing and fittings at your trade plumbing suppliers is, however, more essential today than ever before.
That’s because solar energy has become the 2nd largest source of renewable electricity generation in Australia (Clean Energy Council, April 2024).
Ensuring a roof is watertight when solar panels are installed is different from fitting DWV (drain, waste, vent) pipes. Here, the weakest point will be where the wiring enters the roofing system.
In this article …
You’ll get the lowdown on :
- Roof flashing compatibility to different types of metal roofing materials, including COLORBOND® steel.
- Appropriate roof flashing for solar installations, as set out by Australian Standards.
- A range of solar roof flashing components for different applications.
Check out our Solar Roof Flashings – for metal and tile roofs.
Solar roof installations rise to 1 in 3 Aussie households
More solar panels are now being seen on the roofs of Australian homes and small businesses.
At the start of October 2024…
- Over a third (36 per cent) of households now use a PV (photovoltaic) system to generate electricity.
The number of solar roof panel installations has steadily increased over the last 2 decades.
- 3.72 million – 2024
- 2.33 million – 2015
- 2.12 million – 2004
(Source: Clean Energy Regulator, Australian Government, 2024)
It means that rooftop solar electricity now generates around 11.2 per cent of Australia’s power supply, according to the Clean Energy Council, April 2024.
The right roof flashing for the task
The key task for roof flashing is always to:
- Secure a water-tight seal around roof penetrations, whether it’s for drainage or waste pipes, vents, chimneys, skylights, attic fans, satellite dishes or electric conduits.
This means… installing the right rooftop flashing has always been important. Particularly, in the harshest extremes of the Australian climate.
Bushfire attack levels in areas such as Victoria and New South Wales regularly cause the most devastating damage to property. In nearly all cases:
- The roof surface is a first point of contact for radiant heat and airborne burning embers.
Roof flashing components, therefore, play a major role in securing a roof’s entire surface integrity. By always matching what each does and how they are installed according to:
- Roof pitch
- Roofing material, structure and surface type
There are, however, specific requirements that roof flashing must also satisfy for solar applications.
Types of metals used in roof flashing
Bulk plumbing supplies may offer several types of metal flashing, including, aluminium, galvanised steel, lead, copper and stainless steel.
- Aluminium Flashing – a commonly used, flexible, lightweight and low-cost option
- Galvanised Flashing – similar to aluminium but more rigid and wind-resistant.
Both aluminium and galvanised flashing are installed by inserting underneath the roof shingles, and secured to the roof by roof nails or the weight of the roofing material itself.
- Rubber Flashing – Rubber/EPDM flashing inserted into the opening of aluminium flashing where a roof penetration is to be located. Its highly effective watertight seal does not rely on redirecting water away from the penetration.
While both standard flashing and solar roof flashing are usually made from thin metals,
solar roof flashing is often made from aluminium, which is lightweight, flexible, resistant to rust and corrosion, and easy to install.
COLORBOND® roofing and compatibility with metal flashing
Almost half (49 per cent) of all roofs in Australia are reported to be commonly made of COLORBOND® steel (Australian Roofing Survey Report, 2022).
The clear, straightforward advice for the installation of solar panels on a COLORBOND® roof is:
- NO contact that could create an electrical connection
This means there should be NO direct contact with flashings made from stainless steel, lead, brass and copper.
In addition …
Avoid using flashings made from copper and lead that can potentially create:
- Water run-off onto roofing made from COLORBOND® steel resulting in bi-metallic / galvanic corrosion*.
*Galvanic corrosion occurs when two different metals touch, creating an electric current to flow between them, and causing one of the metals (known as the “anode”) to corrode faster.
IMPORTANT:
Roof flashing products made with stainless steel are the ONLY materials that can be safely used with a roof made with COLORBOND® stainless steel.
Roof flashing made from zinc-coated steel, COLORBOND® steel is also NOT compatible with COLORBOND® stainless steel.
Technical Bulletin TB-8 Flashing materials for COLORBOND® steel* states:
- “Any penetrations through the roof should be placed in such a manner so as to minimise the risk of water ingress”.
- “Penetrations through the roofing sheet should be properly sealed using appropriate flashings and sleeves, and/or neutral-cure sealants”.
(*Referencing: Australian Standards AS/NZS 5033 Installation and safety requirements for photovoltaic (PV) arrays).
Solar roof flashing versus standard roof flashing
The main difference between and standard roof flashing and solar roof flashing is:
- Protection against ultraviolet (UV) radiation
- Forms a weatherproof seal around solar panel wiring entering the roof system
Another crucial difference will be how flashing is installed.
- Solar flashing should be positioned into place before the mounting system used for solar panels is installed.
In a nutshell …
Solar roof installations have risen to more than a third of all home and business buildings.
This means ensuring compatibility with the right roof flashing materials and components. In the same way as selecting the correct roof flashing to securely seal roof penetrations for DWV pipe systems.
The key protection given by solar roof flashing is against ultraviolet (UV) radiation and specific weatherproof sealing for solar panel wiring entering the roof.
While solar roof flashing is often made from aluminium, there should be NO direct contact with flashings made from stainless steel, lead, brass and copper on a roof made with COLORBOND® steel.
FAQs
Q: Where should holes for solar roof flashings be made?
A: Always in the high, upper area of a roof surface. This will also prevent the risk of leaking to the lower roof area.
Q: How do metal roof flashing components make a leakproof seal to a metal roof?
A: Most are made with synthetic, flexible, rubber surface mounting known as EPDM, which has a low electrical conductivity and is water resistant.
Q: How do UV rays damage a roof?
A: UV rays penetrate roofing materials and alter their chemical structure. The roof surface can quickly degrade as it dries out, becomes brittle, and eventually leads to hairline cracks forming.
Looking for solar flashings – EPDM-sealed and UV ray resistant –
for metal and tiled roofs?
