From counter-flashing to valley flashing, aluminium to galvanised steel; no matter the material or type, flashing is one of the essential elements in creating a weather-resistant barrier system for the roof of your property.
But what is flashing, and how do you install it on your roof? Follow on to learn more about roof flashings, what jobs each type does and how to install flashing materials on your roof.
What is Roof Flashing?
Roof flashing is a thin material used for waterproofing rooftops. Every roof has ‘penetrations’ – openings or holes in the surface that house features like chimneys, skylights and vents. These necessary holes can become water entry points if not sealed correctly – enter, roof flashing.
Roofing professionals install flashings wherever the roof plane meets a vertical surface, e.g. a chimney wall or dormer. The materials must overlap to allow water to flow away in the right direction without seeping through the roof surface. Redirected water then runs down the flashing material toward the shingles to prevent leaks and protect the home’s interior below.
What is Roof Flashing Made Of?
The type of roof flashing material depends on budget, whether the flashings are concealed or exposed, and if they are compatible with existing roof materials. You want your roof flashing to look good! So it’s crucial to think about how your flashings will integrate into the design of your house. Another vital consideration is the flexibility of the materials – roof flashing needs to bend to fit the shape of your roof.
Metal and rubber are the most common materials used for roof flashing. There are three primary materials, each with its properties and benefits:
- Aluminium is the lightest and easiest material to manipulate; however, aluminium flashing does need coating so that it doesn’t degrade. It is vital to coat aluminium roof flashings in coastal areas to prevent corrosion.
- Copper is malleable and easy to solder, making it ideal for use around chimneys. Copper is highly durable, and while some people like its discolouration over time, it’s a deal-breaker for others!
- Steel is the most popular and commonly used flashing material. It looks good, is malleable and durable, and is protected from corrosion when galvanised.
Types of Roof Flashing
Let’s look at some of the different kinds of roof flashing.
Sometimes called ‘apron flashing’, continuous flashing is one long piece of material used to protect a joint or divert water from a vertical surface into a gutter.
This kind of flashing acts as the first of two materials used to protect certain roof features, like chimneys, by making sure rain always hits a surface that will direct it downwards.
This type of flashing sits over the edges of your roof to protect against rainwater blown in by the wind. It’s vital to get the correct barge flashing materials for the roof you have – faulty materials or installation can mean a wet house.
Wall flashing can be embedded in a wall to stop water from getting in or redirect water that has already gotten through.
Valley flashing fixes into the roof valleys formed where two roof sections meet, so water runs down and away from the roof surface.
Box gutters are a type of flashing, but they also drain water away from a roof. They fit in where roof sections meet or between an exterior wall and the roof.
Ridge flashings fix on to the top ‘ridge’ of apex roofs, where the two sloping sides meet in the middle. Ridge flashings prevent water from getting in through the exposed seam.
Installing Roof Flashing
Having professionals who understand safety standards and adhere to the building code carry out roof flashing installation is always best. Installing roof flashing can be a long and tricky process, so unless you have experience, we advise getting a roofer in.
The installation process varies depending upon the type of flashing materials you’re working with, but the basics remain the same for the most part. Three flashing techniques are suitable for different areas on the roof; some techniques work better with specific types of flashing. Let’s take a look at flashing techniques:
- Step flashing: Step flashing is where your sheet metal is layered from the bottom up, overlapping to form ‘steps’ that rainwater will run down. Use this method where the roof meets a vertical surface, like a dormer or a skylight. Water can leak through the shingles into the property; step flashing redirects any water into a gutter to drain correctly.
- Counter-flashing: Counter-flashing consists of two pieces of flashing material – base flashing and counter-flashing – and is most commonly used for chimneys. The base flashing is installed first and sits around the bottom of the chimney. The counter-flashing sits over the base flashing to ensure water doesn’t run through.
- Vent boot flashing: Sometimes just called a ‘boot’, vent flashing matches the cylindrical shape of the vent it fits around. Shingles installed over the base force rainwater to flow around the vent and away from the roof surface.
Importance of Sealant
Sheet metal alone isn’t enough to waterproof those roof penetrations, so you need to use an adhesive sealant when installing roof flashing. Roofing professionals sometimes use nails to secure flashing, deciding whether to attach flashing to the roof surface or the vertical wall; nailing to both risks warping the flashing under the pressure of shifting materials. When fixed only to the roof or the wall, the flashing remains in place even while the other building materials expand and contract.
Roof Flashing In A Nutshell
An incredibly versatile flashing material option is Polyisobutylene, which our Wakaflex comprises. It requires no specialist tools and is compatible with most roof materials, making it quick and easy to install using the techniques above.
Though flashing isn’t the most exciting part of roofing, it is undoubtedly one of the most vital elements in making your roof safe, secure and watertight. Check out the range of roof flashings we offer, using the most durable and flexible materials.