What Makes Pitched Roof Lead Flashing Different
When customers ask me about lead flashing on a pitched roof, they usually point to the chimney and say, “Is that the bit that’s leaking?” In my 18 years on the roof, I’ve found that pitched roof leadwork fails in very different ways to flat roof leadwork – and the repair approach has to match that.
On a pitched roof, lead isn’t just a strip stuck in a wall joint. It has to cope with wind-driven rain, flowing water from the slope, expansion and contraction, and sometimes decades of movement in the roof structure itself. If you ask me, I’ll tell you straight: most pitched roof leaks I’m called to in Brighton, Hove and Worthing come down to badly detailed or tired leadwork around chimneys, valleys and gable ends.
This page is all about how pitched roof lead flashing actually works in the real world – how it fails, what I look for when I’m up there, and the options you realistically have as a homeowner.
Where Lead Flashing Fails Most Often on a Pitched Roof
On a typical Sussex house, these are the high-risk lead areas I check first:
- Chimney abutments – front apron, back gutter, side step flashings
- Valley gutters – especially where two pitches meet in a V
- Gable verges and upstands – where a pitched roof runs into a wall
- Roof windows and dormers – lead soakers and flashings
- Pitch-to-flat roof junctions – for example, a pitched roof draining onto a flat rear extension
You already know what lead flashing is and why it matters, so I won’t repeat the basics you can read in my roofing lead flashing guide. Here I’ll focus on what usually goes wrong on pitched roofs specifically, and what I actually do to put it right.
Chimney Lead Flashing on Pitched Roofs: The Real Trouble Spots
If your pitched roof has a chimney, that area is almost always the first suspect for damp patches on ceilings or the chimney breast. The weak points tend to be:
- Apron flashing at the front – water hits the chimney and runs sideways; if the apron is too short or poorly lapped, it can drive under the tiles.
- Back gutter at the rear – this has to collect a lot of water; if it’s shallow, undersized, or blocked with debris, water will overflow sideways under the tiles.
- Side step flashing and soakers – on older roofs I see soakers missing altogether, or replaced with a single long strip of lead which splits over time.
In my experience, chimney leaks on pitched roofs usually come from one of three causes:
- Lead cut or fixed in over-length sections that crack
- Mortar joints (the chases) failing and letting water straight behind the lead
- Tiles or slates not correctly lapped over the lead, leaving a capillary path
My honest advice: if you have a recurring leak around a chimney that “keeps coming back” after quick sealant jobs, it normally needs proper re-leadwork with correct detailing, not just another tube of mastic.
Lead Valleys on Pitched Roofs: Why They Leak and How I Approach Them
Valleys are where two roof slopes meet and concentrate all the water into a single channel. When the valley is formed in lead, it can last decades – if it’s been properly detailed and not abused during other works.
Common issues I see with pitched roof lead valleys:
- Valley too narrow for the amount of water it needs to carry, especially on large modern roofs.
- Lengths of lead too long, so they expand and crack down the centre (sometimes hidden under leaves and moss).
- Nail heads exposed where someone has fixed through the lead rather than using clips or correct fixings.
- Tiles cut too tight into the valley so debris builds up and dams the water.
On a survey I always check the laps between valley pieces, the condition of any central crack, and how the tiles have been cut into the valley. A neat looking valley can still leak if the laps are tight or the lead has hairline splits.
What I actually do will depend on the condition. Sometimes I can cut out and replace a single failed section of valley; other times the best option is to strip the tiles either side, renew the valley properly and relay the area so the water can actually flow.
Lead Flashing at Gable Ends, Party Walls and Roof Abutments
Terraced and semi-detached houses in Brighton and Hove often have one pitched roof side running hard into a higher brick wall. This is where you’ll find step flashing, cover flashings and soakers – and quite often a mixture of lead, cement and old repairs.
Typical problems I see on these pitched roof junctions:
- Rendered over lead – someone has tried to hide the flashing behind render, which then cracks and lets water behind.
- Short lead upstands – the lead doesn’t come high enough up the wall, so driven rain can pass over the top edge.
- Mismatched levels after a neighbouring roof or loft conversion, leaving steps where water can sit.
On these jobs, I look at the whole run of the roof, not just the one damp patch you can see inside. Sometimes the actual failure is about a metre uphill from the stain on your ceiling.
Leadwork Around Roof Windows and Dormers
Modern roof windows (Velux and similar) usually come with their own flashings, but many older dormers and hand-built details still rely on traditional lead. I regularly see:
- Soakers omitted on one or both sides of the dormer cheeks
- Flat back gutters behind dormers where water just sits
- Lead dressings nailed in the wrong place, so nail holes slowly pull open
If you’ve had a loft conversion and the new room leaks around a roof window or dormer, the issue is often in the detailing where new work meets your old pitched roof. That’s why I often inspect the whole area, including tiles, underlay and battens. If the supporting structure is rotten, sometimes the job becomes a targeted batten and felt replacement as well as new leadwork.
Why “Just Resealing the Lead” Rarely Works Long-Term
A lot of the pitched roof leaks I’m called to have already had one or two mastic or “black goo” attempts. If you ask me, I’ll tell you straight: sealant on lead is nearly always a temporary patch at best.
Here’s why simple resealing often fails on pitched roof leadwork:
- Movement – pitched roofs move with wind and temperature; sealant can’t stretch enough long term.
- Water flow – on a slope, water is constantly running over the repair, so any small gap is quickly found.
- UV and weathering – products that look fine at first can crack or peel within a year or two.
That doesn’t mean every job needs a full strip and re-lead. But it does mean I’m honest about when a sealant repair is just buying you a bit of time versus actually fixing the underlying issue.
How I Diagnose Pitched Roof Lead Flashing Problems
When I’m called to a pitched roof leak that might be lead-related, I don’t just jump straight into repairs. My on-site routine looks roughly like this:
- Talk to you about the leak – where it shows inside, when it happens (constant, only in heavy rain, only in wind from one side, etc.).
- External visual check from the ground – chimney, valleys, gables, any obvious cracks or bodged repairs.
- Safe roof access – usually scaffold or a safe roof ladder if appropriate.
- Close inspection of leadwork – I check laps, chases, fixings, and carefully look for hairline cracks.
- Check the surrounding roof build-up – tiles/slates, underlay, battens, and any nearby junctions (gutter, flat roof join, neighbouring roof).
Sometimes the lead itself is still sound and the real culprit is a broken tile, rotten batten, or underlay that’s perished behind the flashing. I’m not interested in selling you leadwork you don’t need; I’m interested in finding the exact route the water is taking and stopping it.
Repair Options for Pitched Roof Lead Flashing
Once I’ve found the source of the problem, the repair options generally fall into three categories.
1. Localised Lead Repairs
This is possible when the damage is small and the surrounding detailing is still sound. Examples include:
- Replacing one short section of cracked valley lead
- Re-doing a short run of failed step flashing on the weather side of a chimney
- Re-fixing loose flashing where the chase has opened up
This can be cost-effective on otherwise solid pitched roofs, but I’m careful not to promise miracles where the rest of the lead is at the end of its life.
2. Partial Re-Leading Around One Feature
Sometimes the best middle ground is to completely re-lead one junction properly, for example:
- Full chimney re-lead – new apron, back gutter, side steps and soakers
- Full replacement of a valley from ridge to eaves
- Re-lead of one full abutment where your roof runs into a higher wall
On these jobs I will usually strip back tiles or slates, check the timbers and underlay, and make sure everything under the lead is sound before I sign off.
3. Leadwork as Part of a Bigger Pitched Roof Job
If your whole pitched roof covering is coming to the end of its life – crumbling battens, perished felt and lots of broken tiles – it can be a false economy to do lots of new leadwork onto a failing roof structure.
In those cases I’ll be honest with you: you may be better off looking at a more comprehensive repair or even a full pitched roof refurbishment for that slope, with new leadwork installed at the same time. It costs more up front, but you’re not paying twice for access and piecemeal repairs.
Access and Scaffolding: The Part Everyone Forgets
One thing that often surprises people with pitched roof lead flashing work is how much the access affects the price. Lead is heavy, detailed work, and I need safe, solid footing to do it properly – especially around chimneys and valleys high up on the roof.
In many cases, a proper repair will require at least a small scaffold tower or a short run of scaffold to the relevant elevation. If you’re planning other roof work at the same time, I can help you estimate likely scaffold costs using my rough scaffolding price calculator so there are no surprises.
How I Keep Pitched Roof Leadwork Transparent and Stress-Free
The roofing trade doesn’t have the best reputation for communication, so I do things a bit differently.
- Instant online estimates – for many leadwork jobs you can get a realistic guide price online using my lead flashing cost calculator, without any commitment.
- Fixed-price quotes – after a free on-site survey, I give you a fixed price to carry out the agreed work. No sneaky extras halfway through unless we’ve both agreed to add extra work.
- Client portal – for larger pitched roof or chimney projects I upload daily photos and progress notes so you can see exactly what I’m doing up there without climbing a ladder.
When a Pitched Roof Lead Flashing Inspection Is the Sensible Next Step
If you’re seeing any of these signs, it’s worth getting me out to have a proper look at your pitched roof leadwork:
- Damp or staining around chimney breasts or in bedrooms under the roof
- Leaks that only appear in heavy or wind-driven rain
- Visible cracks or splits in valley lead
- Lead around chimneys or walls that looks loose, lifted or heavily patched with sealant
My honest advice: don’t wait until the plaster is falling off the wall. Lead leaks can be slow and sneaky, and by the time you see water inside, the timber behind can already be suffering.
If you’re in Brighton, Hove, Worthing or the surrounding Sussex area and want me to take a proper look, you can book a free roof inspection and I’ll go through the options with you on-site.
And if water is already coming in and you need me urgently, use my emergency roof leak booking service so I can prioritise your call-out and get the worst of the leak under control before any long-term repairs go ahead.
However we handle it, you’ll get straight answers from me, clear pricing, and pitched roof lead flashing work that’s done properly – not just hidden under another layer of sealant.