Ely Roofers installs and repairs lead flashing for homeowners in Downham Market, helping you decide whether a repair or a full replacement is the right call for your roof.
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Lead flashing is the weatherproofing metal fitted at the junctions between a roof and any vertical surface - chimneys, dormer walls, parapet walls, and the valleys where two roof slopes meet. When it fails, water gets in at the joint and travels inside the structure, often appearing some distance from the actual entry point. Persistent damp patches near a chimney breast, ceiling staining in an upstairs room or a wet loft space are all signs that lead work may be the culprit.
Good lead work uses code 4 or code 5 lead sheet, dressed and fixed to British Standard. Code 4 is 1.8 mm thick and used for most step and cover flashings. Code 5 at 2.24 mm suits valleys and wider applications where the lead is exposed across a greater surface area. Using the correct code matters - undersized lead moves more with temperature change and is more likely to crack over time.
This is the question most homeowners in Downham Market face when lead work starts to fail, and the answer depends on the condition of the existing lead, how it was originally fitted, and how long you want the fix to last.
A repair is appropriate when the lead itself is structurally sound and the problem is isolated - a section of mortar has dropped from a raking joint, a single piece of step flashing has lifted at one end, or a fixing tack has corroded and the lead has shifted slightly. In these cases, the existing lead can be re-dressed, re-fixed and re-pointed, and the repair will hold for many years if the lead is in otherwise good condition.
Replacement is the right answer when the lead has reached the end of its serviceable life. Signs that point to replacement rather than repair include:
A common situation is a chimney stack where the cover flashing (the horizontal piece across the top of the step flashings) has lifted and is clearly visible from the ground. Many homeowners assume this means the whole stack needs stripping. Often it does not - if the step flashings are sound and the lead is a good code, re-dressing and re-pointing the cover flashing is sufficient. But if you look more closely and find the step flashings are also cracking or were originally bedded without clips, doing the cover flashing alone is a short-term answer.
It is worth understanding why sealant on lead almost always signals a future replacement rather than another repair. When sealant is applied over a crack or a lifted edge, it bonds to the surface and appears to stop the leak. But lead continues to move with temperature - expanding in summer warmth and contracting in winter cold. That movement works against the sealant bond, reopening the gap beneath. Meanwhile, moisture trapped between the sealant and the lead surface accelerates corrosion. By the time a second repair is needed, the lead underneath is often in worse condition than it would have been if it had been replaced the first time.
If you have had "repairs" carried out in the past that involved sealant being applied, tell the contractor before they assess the job. It affects how they strip back the old material and what they find underneath.
For a typical chimney step flashing repair, the process involves removing the affected section, raking out the mortar from the masonry joints, cleaning back any debris, and dressing new or re-shaped lead back into the joints. Fixing clips or tacks are used to hold the lead before pointing. The mortar used for pointing needs to be matched carefully to the existing masonry - a cement-heavy mix used on older lime mortar stonework can cause the masonry itself to deteriorate.
For a valley repair or replacement, the tiles or slates either side of the valley need to be lifted to access the lead beneath. The number of courses that need lifting depends on the width of the valley board. This makes valley work more involved than a chimney flashing job of equivalent length.
Replacing lead work on a chimney stack - step flashings, cover flashing, back gutter and front apron - typically takes the better part of a day on a standard domestic stack. The old lead is stripped back, the masonry raking joints are raked out cleanly, and new lead sheet is cut, dressed and fitted from scratch. The back gutter, the tray that sits behind the chimney to divert water around it, is often the piece most likely to have been skimped on in original construction and is worth inspecting carefully during any replacement job.
As a general guide for the UK, a repair to chimney step flashings (re-dressing and re-pointing, lead retained) might cost in the region of £150-£400 depending on how many sections are involved and what access is required. A full replacement of all flashing on a standard domestic chimney using code 4 or 5 lead is more typically £500-£900. Valley lead replacement depends heavily on length and what tiles need lifting but is rarely below £400 for even a short valley run. These are rough UK ranges - get a proper inspection and a specific quote for your own roof before committing to any figure.
If you are unsure whether a repair or replacement is the right move on your Downham Market property, call us to arrange a roof survey. We will inspect the lead properly, explain what we find, and give you an honest assessment of whether repair will hold or whether replacement makes better long-term sense.
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Call any time. Calls are answered day and night and passed straight to our roofers.
