A leak around a parapet wall can be one of the most frustrating roofing problems to diagnose.
You can repoint the brickwork, apply storm seal treatments and even install new lead flashing, only to find the leak returns after the next spell of driving rain.
In this Skillbuilder video, Roger looks at a persistent leak where the obvious repairs haven’t solved the real problem. At first glance, the lead flashing appears sound, yet water is still finding its way inside.
The likely culprit isn’t the lead itself, but what lies beneath it.
When wind-driven rain hits a parapet wall, water can be forced underneath the lead flashing where it meets the plain roof tiles.
If there are no lead soakers or a properly formed secret gutter beneath the flashing, the water has nowhere safe to drain. Instead, it can travel behind the lead and eventually cause a leak inside the property.
This is why investigating a roof leak often requires more than a quick visual inspection. Just because the lead looks neat from the outside doesn’t mean it’s been detailed correctly underneath.
Roger points out that many people are tempted to solve the problem by sealing or sticking the lead down.
While that might appear to stop the leak temporarily, it’s rarely the correct solution.
Lead is designed to move.
As temperatures rise and fall throughout the year, lead naturally expands and contracts.
If it’s fixed too rigidly with adhesives or sealants, that movement is restricted. Over time, this can lead to splitting, distortion and fresh water ingress.
Instead, the focus should be on directing water safely away from the vulnerable junction.
A correctly installed system often relies on hidden lead soakers beneath each tile or a secret parapet gutter.
These details channel rainwater away before it has the opportunity to reach the inside of the building.
You may never see them once the roof is complete, but they’re often the difference between a roof that stays dry and one that develops an ongoing leak.
Fix the Cause, Not Just the Leak
Roofing problems like this are a reminder that treating the symptoms rarely fixes the cause.
Repointing, replacing flashing or applying waterproof coatings can all have their place. But if water is entering because the original detailing is wrong, the leak is likely to return.
Good roofing is about managing water, not simply trying to block it.
Before assuming the lead has failed, it’s worth asking whether the roof was detailed correctly in the first place.
A missing soaker or poorly designed drainage detail can undo even the highest-quality leadwork.
As Roger explains, understanding how water behaves is often more important than replacing materials unnecessarily.
Sometimes the best repair isn’t adding more sealant—it’s installing the detail that should have been there from day one.
_______________________
🔑 Key Insights
• A parapet party wall was originally used to help slow the spread of fire between neighbouring houses.
• Persistent leaks at the edge of a parapet wall can be caused by wind-blown rain, even when the wall has been repointed and the flashing looks neat.
• Plain tiles and slate-style roofs often need lead soakers or a secret gutter beneath the visible flashing.
• Lead expands and contracts, so sticking it down with mastic is usually the wrong approach.
• Long runs of lead need joints to avoid buckling and cracking.
• A properly detailed hidden channel can carry water safely down to the gutter before it reaches the roof structure.
_______________________
Got a question of your own? Send it in — Ask Skill Builder is a free service!
📪 ASK SKILL BUILDER
https://skill-builder.uk/send
Other related websites – https://www.fasciaandsoffitscolchester.co.uk/?gad_source=1&gad_campaignid=142200154&gbraid=0AAAAADq88nbdXu55jQE4M61L_ZN3yJqwQ&gclid=CjwKCAjw6rfSBhAqEiwA_yocpmk-rvGUI-zCHsx7omCVyX5dIrnfOzT1pCs0OlEAlzovUvOfFLf4sBoCF8MQAvD_BwE
We have over 1,300 episodes. Join 740,000 subscribers and help us hit that 1 million milestone!
_______________________
#Roofing #LeadFlashing #SkillBuilder
