Ridge flashing is one of the finishing details that completes a metal roof. Positioned at the highest point, it joins the two roof slopes at the peak and helps create a weather-tight seal. When it is correctly sized, positioned, and fixed, it also gives the roof a clean, professional finish.
The process is fairly straightforward, but accuracy matters. Choosing the right roof flashing, using the recommended stitching screws, and lapping separate lengths correctly all help the ridge perform as intended.
What Is Ridge Flashing and Why Does It Matter
Ridge flashing is a folded metal trim, typically bent to a 130° internal angle, designed to sit over the highest point of a roof and cover the joint where two roof planes meet.
This kind of roof flashing is small but carries an outsized job. As one of the most exposed parts of any roof, the ridge takes the brunt of wind and rain, and a poorly sealed apex is a common cause of hidden leaks. Good corrugated roof flashing at this point also helps ventilate the roof space when fitted correctly, reducing the risk of condensation building up inside.
Step-by-Step Installation Process
Measure the Ridge Line
Start by checking that the ridge flashing has the correct size, angle, and finish for the roof. Standard sections are 3,000 mm long, while ridge lengths can also be available up to 6 metres.
Keep the protective film in place during handling where practical, as it helps prevent scratches during installation.
Position the Flashing Over the Roof Apex
Place the ridge flashing over the highest point of the roof where the two slopes meet. The folded centre should follow the apex, with each side extending over the roofing sheets.
Before fixing, check that both sides sit consistently so the run looks straight and provides even coverage. This is particularly useful when fitting corrugated roof flashing over profiled sheets.
Secure the Ridge Flashing With the Recommended Fixings
Once the flashing is positioned correctly, secure it using the recommended MS202/G16 stitching screws. These fixings are designed to provide a self-tightening action for a snug fit.
Keep the flashing aligned while it is being fixed and follow the recommended screw type.
Lap Additional Sections for Longer Runs
If the ridge is longer than one flashing section, more than one piece will be needed. Each flashing should overlap the next to create a secure fit. Keep the sections aligned so the lap maintains continuous coverage along the roof.
Check the Finished Ridge
After fitting, inspect the complete run. Check the alignment, fixings, and lapped joints, and make sure each section sits evenly over the apex. The finished corrugated metal flashing should form a neat, continuous line across the ridge.
Why the Right Fixings and Overlaps Matter
Performance depends heavily on the fixings and overlaps used, not just the trim itself. Self-tightening stitching screws draw the flashing down snugly without constant adjustment, reducing the chance of movement over time.
Overlaps matter just as much. A shallow or inconsistent overlap creates a natural entry point for water. Overlaps should be generous enough to shed water cleanly and fixed at both ends so wind cannot work the joint loose.
Common Ridge Flashing Installation Mistakes to Avoid
Checking the product and roof before fixing can prevent several common mistakes.
- Choosing the Wrong Size: Select the ridge width that suits the required coverage rather than choosing a section without checking its dimensions.
- Poor Alignment: Position the flashing centrally over the apex so the finished ridge does not wander or sit unevenly.
- Using Unsuitable Fixings: Use the recommended MS202/G16 stitching screws to achieve the intended snug, self-tightening fit.
- Forgetting the Overlap: When several sections are needed, lap each flashing with the next instead of placing the ends together.
- Damaging the Finish: Leave the protective film in place during handling where practical, and treat the surface carefully to reduce scratches.
- Skipping the Final Check: Review the whole ridge after installation for secure fixings, neat joins, and consistent positioning.
Taking a little extra time during positioning can prevent problems later in the installation.
Maintenance Tips for Long-Term Performance
Ridge flashings are designed for a durable, weather-tight finish, but occasional visual checks can help you spot anything that has changed since installation.
- Check the Fixings: Look for stitching screws that appear loose or no longer hold the ridge securely.
- Inspect the Laps: Make sure adjoining flashing lengths remain aligned, and the lapped sections still form a secure connection.
- Look for Visible Damage: Check the finish for obvious scratches, dents, or marks that may have occurred after fitting.
- Review the Alignment: The ridge should continue to sit evenly along the roof apex without sections appearing displaced.
- Check the Overall Finish: Look across the full ridge to confirm the metal flashing remains neat and consistently positioned.
Paying attention to these checks helps preserve the secure fit and tidy finish established during installation.
Final Thoughts
Ridge flashing sits at the very top of the roof, but its role is central to keeping the whole structure watertight. With accurate measuring, the right fixings, generous overlaps, and a finish suited to the building, a professional, long-lasting result is well within reach.
For anyone sourcing materials for the job, Colour Clad Profiles supplies precision-folded ridge flashings in galvanised, polyester, and plastisol finishes, ready to meet the demands of any roofing project. Backed by clear specifications and dependable stock, Colour Clad Profiles makes it straightforward to find the right trim for a secure finish.
Frequently Asked Questions
What angle do most ridge flashings use?
Most ridge flashings are folded to a standard 130° internal angle, suiting the majority of common roof pitches. This allows the flashing to sit closely against both slopes, forming a tight seal at the apex.
Can ridge flashing be used on corrugated roofing sheets?
Yes, ridge flashing works with corrugated metal flashing profiles as well as box profile sheets. It sits over the crown of the corrugations and fixes through the raised sections.
Why is ventilation important at the ridge?
Leaving some airflow at the ridge helps prevent condensation from building up inside the roof space. A fully sealed apex without ventilation can trap moisture and lead to damp issues.
Does ridge flashing need sealant as well as fixings?
In many cases, filler strips or sealant close small gaps beneath the flashing. Some areas are deliberately left open for ventilation, so sealant should only be used where the roof design calls for it.
How many fixings are needed per length of ridge flashing?
The exact number depends on length and roof profile, but fixings should be spaced evenly and secured at both ends of each overlap. Even spacing helps distribute wind load and prevents lifting.
