A roof may seem like a simple structure – but in reality, a modern roof is actually a complex system of materials and construction processes designed to protect your home from all kinds of weather under all sorts of conditions.
Understanding how your roof system works is not only helpful in maintaining its appearance, it can also have the added benefits of increased durability and extended longevity. One of the most important yet often under-estimated parts of the roofing structure is roof flashing – without proper flashing, your roof would leak all the time, and you’d end up with a lot of costly damage to your home and contents.
To help you get a better idea about roof flashing, let’s discuss some of the terms and techniques used by professional roofers. We will cover the most important aspects of roof flashing, the different types of flashing and the different kinds of materials they can be made from.
What Is Roof Flashing?
Flashing is the trim that provides protection for roof joints, preventing water from leaking through. For that reason it is one of the most important parts of the roofing system. Roof flashing is typically installed over ridges, around edges, along the tops of walls, in roof valleys, as well as around chimneys and vents or other protrusions in the roof or where the roofing materials meet at a junction. Getting your flashings right is a necessity for ensuring a water-tight result.
Roof flashings in New Zealand are usually made of metal in the same material and finish as the roof cladding (more on this below). The purpose of flashing is to form a protective barrier on an otherwise exposed connection between the roofing materials, wall materials and other protrusions. Providing this weather-tight surface is designed to prevent water from entering the building and also to deflect water away from the building where possible.
Where To Find Your Flashings
Flashings are required in all situations where the cladding has ended or meets other forms of cladding, this includes:
- Ridges and valleys
- Around the roof edges and barges
- At changes in roof pitch such as hips and gables
- Around penetration holes through the roof (vents/pipes etc.)
- Around doors and windows
- At intersections between different building elements, both vertically and horizontally
- Under guttering
- At soffits, parapets and balustrades
How To Select Flashing Materials
When choosing flashing materials, there are six main points under the NZ Building Code requirements to consider:
- The Durability Requirements Of The Building Code. Found under clause B2 of the code.
- The Build Environment. Exposure conditions for the specific location are also a factor. For example, is it located by the ocean, where salt air is a factor to consider?
- Compatibility With Surrounding Materials. Whether or not the material will work in with the other materials the building is made from. Each type of flashing material has its own manufacturer and Building Code compatibility recommendations.
- Possible Effect Of Thermal Movement. Significant changes in temperature can affect the resilience of some building products due to the associated expansion and contraction.
- Limitations On Flashing Lengths. Some roofing materials can only be manufactured/supplied in certain lengths which could affect your options depending on the scope of the project.
- Water Collection Suitability. Roofs where water is intended to be collected for consumption/usage will need careful consideration when it comes to roofing materials. This is because the choices made could have an effect on the quantity and quality of the water collected.
Materials Most Commonly Used For Flashing In NZ
The most commonly used flashing materials in NZ are:
- Galvanised steel
- Zinc alloy-coated steel
- Pre-painted steel
- Copper
- EPDM flashing (such as Dektite)
- Bituminous flashings
- uPVC
- Aluminium
- Stainless steel
Less commonly, materials like zinc, and lead are also permitted.
6 Types Of Roof Flashing
There are a number of different types of flashing suited to different parts of your roof. The type of flashing will also be determined by the materials being used. Understanding the different types and how they are installed will help you make sure your roof is well protected.
1. Apron Flashing
L-shaped flashing that runs parallel to the roof cladding and usually fits behind or against wall cladding. It is commonly used for joins between the roof and walls where two different types of cladding meet.
2. Barge Flashing
Inverted L-shaped flashing with a kink at both ends that also runs parallel to the cladding and is used on gable ends to secure the edges of the cladding.
3. Ridge Flashing
Flashing formed into a peak type shape with either square or rolled top configurations. Used in ridge, apex or hip-end joints.
4. Valley Flashing
V-shaped flashing used at the gutter or internal intersection of two downward sloping roof pieces. When installed correctly, valley flashing should direct water into your gutters.
5. Cap Flashing
Open-edged square shaped flashing used to “cap” the top of a parapet or wall. Sometimes referred to as ‘Parapet Top Flashing’. Must be installed over parapets or enclosed balustrades.
6. Boot Flashing
EPDM (Ethylene Propylene Diene Monomer Rubber) flashings such as Dektite (made from a silicone polymer) are used to form a more flexible seal around pipes, vents, chimney flues and ducts that penetrate roofs or walls.
Top 5 Roof Flashing Maintenance Tips
Now that we’ve discussed all the ins and outs of flashing, it would be good to know a few installation and maintenance tips so you can keep your roof in tip-top shape. Here are a few tips to help you maintain your flashing or at least keep an eye on it and know when to call the roofing professionals.
1. Carry Out An Annual Inspection
Any issues with your flashing will be picked up in your annual roof inspection, but if you haven’t had one in a while or prefer the DIY approach, then here are a few things to keep an eye out for when inspecting your roof.
- Holes
- Leaks inside your home
- Rusty bits, or rust stains down your walls
- Cracks or buckled metal
- Deteriorated roofing materials near flashing areas
2. Keep It Secure
Leaks can often originate from flashing materials that are damaged, loosened, or missing. If you notice any movement in the flashing, secure it promptly with the appropriate accessories. It also pays to note; it may be necessary to replace the sealant around flexible flashings more often, especially if you notice deterioration or cracking.
3. Never Reuse Old Flashings
Reusing old flashing when having work done on your roof or replacing it is never a good idea. The smallest defect, scuff, crack or even scratch can quickly develop into a problem, jeopardising the integrity of your new roof or roof repair.
4. Regular Cleaning Is Essential
Regularly cleaning off any debris, dirt and moss/lichen growth from your flashing will keep it functioning at its best for many years to come and even extend the lifespan of your roof. However, avoid using abrasive materials and harsh chemicals as these can damage the surface compromising the integrity of the flashing over the longer term.
5. Ensure Flashing Is Installed Correctly
The easiest way to make sure flashings are installed correctly is to hire a professional roofing contractor, see here for more information on how to find a roofing contractor near you. Flashing installation requires speciality skills and knowledge this is definitely not a DIY job.
Understanding the different parts of your roofing system will help you make informed decisions when it comes to roof replacement or repairs. Protect your home for years to come with trusted roofing contractors Action Reroofing for all your roofing needs – give us a call today!
