If you've spotted damp patches near a chimney or a valley on your Attleborough property, failing lead is the most likely cause and it needs attention before the damage spreads inside.
Lead is the most durable material available for flashings, valleys, parapet copings and chimney soakers, but it doesn't last forever, and when it starts to fail it does so in ways that aren't always obvious from the ground. Understanding the warning signs - and what drives the deterioration in the first place - can save you a significant repair bill further down the line.
A common problem in older properties is lead that was dressed correctly when it was installed but has since been left unattended. Lead moves with temperature. It expands in warm weather and contracts in cold, and over many years that repeated movement causes joints to open, fixings to work loose and, eventually, sections to lift or crack. Once water finds a gap, it tracks along timber and masonry before it shows itself as a stain on a ceiling - by which point the damage behind the plasterwork may already be considerable.
You don't need to get onto the roof yourself to spot early trouble. A pair of binoculars and a clear day will show most of what you need to see. Look for these indicators:
Thermal movement is the primary cause. Lead has a high coefficient of thermal expansion, which means a long run of lead fixed rigidly at both ends will buckle or split under the stress of repeated expansion and contraction. The traditional answer is to work in short bays, typically no longer than 1.5 metres for most applications, with proper expansion joints between them. Lead fixed in one continuous sheet beyond that length will fail prematurely regardless of how well it was dressed initially.
Corrosion is another factor, though it affects lead less than most metals. The real vulnerability is contact with certain materials - wet lime mortar, oak timber and some moss and lichen treatments can accelerate surface breakdown. Lead laid over treated timber or in contact with aggressive pointing compounds will show surface pitting and erosion faster than lead in straightforward contact with brick or tile.
Poor original installation causes a large proportion of failures. Lead that hasn't been properly dressed into the detail - where the sheet doesn't follow the profile of the tile or slate beneath it, or where the upstand behind a chimney is too shallow - will allow wind-driven rain to get behind it from the start. An upstand of less than 75mm against vertical masonry is below the accepted minimum for most pitched roof details, and properties with low-pitch sections or flat abutments need even more height to cope with driven rain.
Age alone eventually brings any lead to the end of its serviceable life. Well-installed lead in a typical domestic application might last 50 to 80 years. Lead on north-facing slopes that stay damp and encourage moss growth, or lead on very shallow pitches where water sits rather than runs, typically deteriorates faster.
Cutting a quick patch and pointing over it isn't a repair - it's a delay. A proper job starts with stripping out the failed lead completely so the detail underneath can be inspected. Timber laths or sarking boards beneath a valley or behind a chimney are often damp or damaged, and those need to be dealt with before new lead goes in. Fixing new lead onto rotten or waterlogged timber is a false economy.
New lead should be cut to the correct width for the application, dressed carefully to the profile of the surrounding materials and fixed with the right clips or tacks - not nailed through the face, which splits the lead under thermal movement. Step flashings should be cut individually and lapped correctly, with each step tucked into the mortar joint above it. Cover flashings should overlap by a minimum of 75mm and be properly chased and pointed, not just surface-bedded.
For valleys, the lead should be formed with proper drips at each bay change, with adequate side laps onto the tile or slate on both sides. A valley that drains slowly or pools water needs a steeper fall, and sometimes this means adjusting the boarding beneath the lead rather than just laying a new sheet over the existing profile.
Costs vary considerably depending on what needs doing and how accessible the area is. As a rough guide, re-leading a chimney stack on a standard two-storey property - including back gutter, soakers and cover flashings - typically costs between £500 and £1,200, depending on the size of the stack and what's found underneath. Valley replacement on a typical semi-detached or detached property usually runs from £400 to £900 for the lead work itself, more if boarding needs to come up.
Small flashing repairs - re-pointing a cover flashing that's still sound, or replacing a single lifted section - can be done for considerably less, but only where the underlying lead is genuinely in good condition. If the lead is crazed or cracked, pointing it back in prolongs the problem by a year or two at best.
Parapet copings in lead, common on older attached properties, typically cost £80 to £150 per linear metre to replace, depending on the width of the parapet and access conditions.
We work across the surrounding area. The same range of details - chimney flashings, valley linings, parapet work and abutment flashings - comes up regularly across the mix of property types in this part of Norfolk.
We cut and dress lead on site rather than using pre-formed sections wherever the detail requires it. Traditional hand-dressed lead follows the exact profile of the roof it's fitted to, which matters on older properties where nothing is quite uniform. Getting the detail right at the time of installation is what determines how long it lasts.
Before agreeing to any lead work on your property, it's worth being clear on a few points:
These aren't difficult questions, and a contractor who knows their trade will answer them without hesitation. If the answer to any of them is vague, that's useful information before the job starts rather than after it goes wrong.
If you've seen any of the warning signs described above - damp patches, lifting flashings, staining inside near the chimney breast - call Thetford Roofers for a roof survey. We'll tell you honestly what the lead is doing, whether it needs full replacement or targeted repair, and what the work will involve. We cover Attleborough, Watton and the surrounding villages from our base in Thetford.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
