Understanding what a proper lead work job involves, from the first look at your roof to the final tidy-up, helps you know whether the work has been done right.
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Lead flashings, valleys and soakers are among the most skill-intensive parts of roofing, and they are also among the most frequently done badly. We cover Sudbury and the surrounding area for lead work on chimneys, dormers, abutments and valleys. This page walks through every stage of a lead work job so you know exactly what to expect.
Every lead work job starts with a proper close-up look at the existing installation. Ground-level inspection from the street tells you very little - a flashing that looks intact from below can be lifted, cracked or completely detached at the back where it meets the masonry. Safe access to the roof is the first requirement.
The inspection covers the condition of the existing lead, the width and depth of any chase cut into the brickwork, the state of the mortar pointing in the chase, and whether the lead is properly clipped or simply wedged in place. On a chimney job, the condition of the brickwork and the chimney's pointing is checked at the same time, because fitting new lead to a stack that needs repointing separately would mean disturbing the new flashings when the repointing is done later.
The condition of the tile or slate courses immediately around the lead is also checked. Broken, slipped or missing tiles at the base of a flashing allow water to get in from a different route and can be mistaken for a lead failure. Identifying every source of water ingress in one inspection prevents the situation where a lead repair is completed but damp continues because a second problem was not spotted.
When replacement rather than repair is needed, the old lead is stripped back carefully. On a step flashing at an abutment, each piece of lead is removed from the chase in sequence, working from the top of the slope down. On a chimney, the cover flashing, the stepped or soaker flashings, and any back gutter lead behind the stack are each taken off in turn.
Old lead from a removal is worth something as scrap and should be removed from site properly. If a roofer proposes to simply fold the old lead back and dress new lead over the top of it, that is not best practice. You cannot guarantee a proper fit or bond when working over an irregular existing surface.
Once the old lead is off, the chase in the masonry is raked out and cleaned. Any loose mortar, old sealant or debris is removed from the joint so the new lead has a clean, square channel to be turned into.
A chase that is too shallow will not grip the lead properly. The correct depth for a chase is typically 25 mm, enough for the lead to be turned in securely and still have mortar behind it. If the original chase is too shallow or has been damaged, it is cut deeper before new lead is fitted.
For step flashings at a side abutment or dormer, the individual soakers are fitted first, one beneath each tile or slate course, before any of the cover flashings go on. Soakers are cut and dressed individually, each one overlapping the one below by the correct amount. This is time-consuming work but it is what makes the junction watertight at every course, not just at the surface.
Lead clips are prepared and fixed at this stage too. Clips are cut from the same grade of lead and fixed to the underlying structure using copper or stainless steel nails. Each strip of cover flashing will be clipped at intervals of no more than 450 mm. Relying on mortar alone to hold lead in place is a common shortcut that leads to lifting and failure within a few years.
Dressing is the process of shaping the lead to fit precisely against the surfaces it needs to seal. A flat piece of lead sheet does not naturally fit against a corner, a change in angle, or the stepped profile of a brick course. It has to be worked with specialist tools: bossing mallets, lead dressers and chasing tools.
At an internal corner, such as where a back gutter meets the side of a chimney stack, the lead is bossed into a three-dimensional shape without cutting. Cutting a corner and lapping two pieces of lead creates a potential water path at the seam. A properly bossed corner has no seam at the vulnerable point and is significantly more watertight as a result.
Each strip of flashing is turned up against the wall surface and simultaneously turned back into the chase, ensuring it seals at both faces. The bottom edge of a cover flashing is usually dressed outward slightly to direct water away from the wall rather than letting it run behind the lead.
Strip lengths are kept within the limits set by good practice, typically no more than 1.5 metres per piece, to allow for thermal movement. Longer strips buckle as the lead expands in summer heat and can crack as it contracts in cold weather.
Once the lead is dressed and clipped in place, the chase is pointed. A lead-compatible mortar or an appropriate flexible sealant is packed firmly behind and over the turned-in edge of the lead, filling the chase and preventing wind and rain from getting behind the flashing. The pointing is finished neatly so it does not overhang the lead face where it could trap water.
On older brickwork, mortar pointing in the chase can break down again within several years due to movement and weathering. This does not mean the lead itself has failed - re-pointing the chase is a maintenance task that a homeowner can watch for and address early rather than waiting for a full lead failure.
Once the lead is in place and the pointing has been done, the work is checked over before the roofer comes off the roof. Every joint and overlap is inspected, every clip location is confirmed, and the chase is checked for any gaps in the pointing. The surrounding tiles or slates are also checked and any that were disturbed during the work are re-bedded or re-fixed.
On a chimney job, the flaunching at the top of the stack is also checked at this stage. Flaunching is the mortar bed that holds the chimney pots and sheds water outward from the pot bases. Cracked or loose flaunching is a separate but related water entry point that is often worth addressing at the same time as the lead work.
A complete job includes removing all off-cuts, old lead scrap, broken mortar, tile fragments and any other debris from the roof surface, gutters and ground. Old lead is taken away for recycling. The area around the property should be left as it was found.
If you are in Sudbury and want to know more about what a lead work job on your property involves, or if you have noticed signs of a leak around a chimney, dormer or valley, call Bury St Edmunds Roofers and ask for a roof inspection.
Access time - setting up and taking down scaffolding or a tower - can add to the overall programme but is not something that should be rushed.
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