Poringland Roofers handle lead flashing work across Sprowston and the surrounding Norwich area, and this page walks you through exactly what a proper job looks like from start to finish.
Call any time. Calls are answered day and night and passed straight to our roofers.
Lead flashing seals the junction between a roof covering and a vertical surface - a chimney stack, a dormer wall, a parapet, or an abutment where an extension roof meets the main house. When the flashing fails, water gets in at the most vulnerable part of the roof. A proper repair means removing what's failed, preparing the surfaces correctly, and fitting new lead at the right code for the application.
The process below covers a typical chimney flashing replacement, which is the most involved type of domestic lead work. Valley and abutment repairs follow a similar logic, with differences at particular stages.
The job starts before anyone goes up on the roof. From the ground, we look at the chimney stack or dormer from every angle that gives a view. We're checking whether lead has lifted, whether there are gaps between the flashing and the brickwork, and whether any previous repairs with sealant or tape are visible.
We also look inside: any damp patches on ceilings, staining on chimney breasts, or salt deposits on internal brickwork tell us where water has been getting in and for roughly how long. A fresh stain that dries out quickly after rain is different in character from a long-standing damp problem that has started to affect plaster or timber.
For many properties, a scaffold tower or section of scaffolding is needed to reach a chimney stack safely. Working from a ladder alone is not adequate for lead work - you need two hands free to cut, dress, and fix lead properly, and a stable platform matters for quality as much as for safety.
The access method is agreed before work starts and factored into the overall cost. On single-storey extensions or porches, a good set of roof ladders is often sufficient. On three-storey or awkward properties, a full scaffold lift may be needed.
The existing flashing - or the remains of it - is stripped back completely. Any mastic sealant, flashband tape, or crumbling mortar is removed. The mortar joint (called the chase) in the brickwork is raked out to a clean, consistent depth, typically 25mm, so the new lead has a solid slot to tuck into. If the old lead is in sections, each piece is lifted out and checked: occasionally a section can be reused, but more often the full set is replaced to give an even, matched finish.
If there are soakers under the tiles - small individual pieces of lead that sit under each tile course at the side of the stack - they are checked too. Soakers that are in reasonable condition can sometimes be left in place; failed or missing soakers are replaced as part of the job.
Once the old flashing is out, the brickwork is brushed clean and any loose mortar is removed from the raked joint. If the brickwork itself is spalling or the bed joints are failing, those should be made good before the new flashing goes in. Fitting new lead against crumbling brick is a waste of a good material.
The tile surface is swept clear of debris and moss. Any cracked or slipped tiles at the junction are re-fixed or replaced at this stage - it's far easier to sort them now than after the lead is in.
Lead is cut from the roll in sections. The maximum recommended length for a single piece of flashing is around 1.5 metres - longer sections don't allow for thermal movement and will crack or pull away over time. For a chimney stack, this typically means three or four separate pieces: the back gutter, two runs of step flashing (one on each side of the stack), and a front cover flashing or apron.
Each section is cut to the correct width and length, then dressed - shaped by hand with a dresser tool - to follow the profile of the tiles or the angle of the brickwork. A good dressing fits tightly, with no gaps along the bottom edge where water could track behind. On a square chimney stack, the corners require additional care: lead is folded or lead-welded at internal and external corners to maintain a watertight seal.
The correct code of lead is used for each part of the job. Code 4 for soakers and cover flashings, Code 5 for step flashings and back gutters on most domestic stacks. Valleys and parapet gutters use Code 5 or Code 6.
The top edge of each section of flashing is tucked into the raked mortar joint to a depth of around 25mm. Lead wedges are tapped into the joint at regular intervals - typically every 450-600mm - to hold the flashing firmly and prevent it from sliding down. This fixing method allows the lead to move slightly with temperature changes without pulling free.
Nails or clips are used at the lower edge where the lead is fixed to the tile or batten. Lead-headed nails or copper clips are the correct materials - they don't rust and they don't react with the lead.
With the lead fixed and wedged, the mortar joint is filled in over the top of the flashing. The mortar mix needs to be compatible with the existing brickwork - a mix that's too hard will crack as the lead moves. A sand and cement mix with a small amount of plasticiser is generally appropriate. The pointing is finished flush or slightly weathered so that water sheds away from the joint rather than sitting in it.
This step is sometimes skipped or done badly on rushed jobs. Pointing that's been pushed in loosely without proper tooling fails within a season or two, and the flashing lifts again.
Fresh lead has a bright, silvery surface that weathers to a dull grey over time. New lead can also produce white lead carbonate runoff (called patination) in the first months after installation, which can stain tiles and render below. Applying a patination oil to the lead surface before the job is complete greatly reduces this. It's a small step that makes a visible difference to the finished appearance.
Once the lead is in and pointed, we go over the work systematically: checking that each section overlaps correctly in the direction that sheds water, that the bottom edge of every piece is bedded down, and that there are no gaps at corners or junctions. Any tile debris or mortar dropped during the work is cleared from the roof and gutters.
Before we leave the site, we check internally too - if the damp patch that prompted the call is accessible, we revisit it to confirm the likely entry point has been sealed. Drying out of plaster takes time after the leak is stopped, and we'll tell you what to expect.
A full chimney flashing replacement on a standard two-storey property in the Sprowston and Norwich area typically costs £450-£850, depending on the stack size, the code of lead, and the access arrangement. Valley relining runs from around £80-£160 per metre. Abutment flashings from £60-£120 per metre. These figures cover properly specified lead, mortar preparation, wedging, and pointing - not a sealant overlay.
If you've seen damp signs or spotted lifted flashing near a chimney or dormer in Sprowston, call Poringland Roofers and we'll arrange a roof survey to assess what's needed before any work is quoted or started.
No obligation · We'll call you to arrange a free visit
Call any time. Calls are answered day and night and passed straight to our roofers.
