If you need lead flashing repaired or replaced in Lakenheath, understanding what the work involves and what it is likely to cost will help you make the right decision.
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Lead flashing is the strip of dressed lead that seals the joints where your roof meets a vertical surface. The most common locations are around chimney stacks, along the sides of dormer windows, where a lean-to roof meets a house wall, and in the valleys formed where two roof slopes meet. Without a properly fitted lead seal at these points, water tracks down behind the tiles or felt and into the roof structure.
A correctly fitted lead flashing is cut, dressed, and fixed to traditional standards. The lead is stepped or soaked into the mortar joints of the masonry, secured with lead clips or wedges, and pointed over with a flexible sealant or fresh mortar. Done properly, lead flashing will outlast the tiles around it.
Lead is not the only material used for flashing, but it is the most reliable and the most widely used on traditional-pitched roofs. Alternatives such as aluminium strip or self-adhesive rubberised tape are sometimes used on budget repairs, but they do not dress as neatly into masonry joints and they tend to fail sooner, especially on chimney stacks where thermal movement is significant.
The most common point of failure is at the top edge, where the lead is tucked into a mortar joint. Over years of heating and cooling, the mortar holding the lead in place cracks and falls out. Once that top edge lifts, rainwater runs straight behind the flashing and into the wall or roof space below. You often do not notice this until a damp patch appears on a ceiling or chimney breast inside the house.
A second common failure is cracking or splitting of the lead itself. This usually affects older flashings that were fitted in thinner gauges, or repairs that used lead that was too thin for the job. Lead should be fitted in a gauge appropriate to its location: code 4 (1.8mm) is the minimum for most chimney flashings, and code 5 (2.24mm) is used where extra durability is needed.
On valleys, lead can also lift at the edges where it has not been properly secured under the tile course, or where the valley board underneath has rotted. A valley replacement is a more involved job than replacing a simple step flashing, because the surrounding tiles have to be lifted, the board inspected or replaced, and the tiles relaid correctly afterwards.
Pointing over a failed flashing with ordinary sand and cement mortar without re-dressing the lead properly is a short-term fix that usually fails within a year or two. The thermal movement of a chimney stack means rigid mortar will crack again. Using a lead-finishing compound or appropriate flexible sealant makes for a longer-lasting repair.
Lead work pricing depends on several factors: the type of joint being sealed, the amount of lead required, access, and the condition of the surrounding masonry or tiles. The figures below reflect typical UK market rates and are intended as a realistic starting point when you are budgeting or comparing quotes.
A chimney stack requires several separate pieces of lead: apron flashing at the front, step flashings up each side, and a back gutter or soaker at the rear. Replacing all the lead on a standard single chimney stack typically costs in the range of £400 to £900, depending on the size of the stack, the pitch of the roof, and how much of the surrounding pointing and mortar needs attention. A small stack on a low-pitched roof will come in at the lower end; a large Victorian-style stack on a steep roof will cost more.
A partial repair - replacing just the apron flashing or re-dressing a single side where the mortar has failed - is cheaper, typically £150 to £350, but only makes sense if the rest of the lead is in genuinely good condition. If the lead is more than 30 or 40 years old, a full replacement is usually better value than patching.
Dormers have lead at the cheeks (the sides), along the sill, and sometimes a small apron at the base. A straightforward dormer flashing repair on a single window typically runs from £200 to £500. If the timber substrate behind the lead has taken in water and started to rot, that has to be dealt with before the new lead goes on, which adds to the cost.
A lead valley replacement - lifting the surrounding tiles, inspecting or replacing the valley board, fitting new lead and relaying the tiles - typically costs £350 to £700 per valley for a standard run of three to four metres. Longer valleys, steeper pitches, or awkward access (for example, behind a chimney or between two roof sections at different heights) push the price higher.
Where a flat roof meets a wall, a lead upstand seals the joint. Replacing a lead upstand on a standard bay window or small flat roof section typically costs £150 to £400 depending on the length of the run and the height of the upstand needed.
Several factors push a lead work job toward the higher end of any range, or beyond it.
Not every lead work job is expensive. Several factors keep costs reasonable.
An accurate quote for lead work requires a proper inspection of the flashing from the roof level, not from the ground. A quote given from the pavement is an estimate at best. A roofer should get eyes on the existing lead, the mortar joints, the condition of the surrounding masonry, and the tiles or slates around the flashing before giving you a firm price.
When you receive a quote, check that it specifies the lead code being used, what is being replaced versus what is being re-used, and whether the mortar repointing of the joints is included. These details matter, because a quote that uses thinner lead or skips the repointing will look cheaper but is unlikely to last as long.
If you are getting more than one quote, make sure they are like for like. A quote to replace just the apron flashing is not comparable to a quote to replace all the lead on the stack.
A lead flashing replacement follows a straightforward sequence. The old lead is stripped back, the mortar joints in the masonry are raked out cleanly, and the surrounding area is inspected for damage. New lead is cut to length on the ground, dressed to shape, and then fitted section by section into the masonry joints. On a chimney stack this means fitting the front apron first, then the stepped side flashings, then the back gutter in sequence.
The lead is fixed into the raked joints with lead wedges or clips and the joints are then pointed up. Where a flexible sealant is used over the top of the mortar at exposed points, this helps accommodate the small movements that come with temperature change without cracking the seal.
Soakers - small individual lead pieces that fit under each tile course alongside the step flashing - are often omitted on older repairs but are important on a properly executed job. They prevent water from tracking sideways under the tiles toward the junction.
A neat lead job leaves all overlaps pointing downhill, with no exposed cut edges that could catch water. The surface should sit tight against the masonry with no gaps visible and no lifting at the corners.
We carry out lead work across Lakenheath and the surrounding area. Whether the job is a chimney stack on a detached house or a dormer on a bungalow extension, the same standards apply: correct lead gauge, properly raked joints, soakers where the roof design needs them, and mortar pointing that will move without cracking.
If you have a damp patch near a chimney, a dormer, or a valley, or if you can see that the mortar around your flashing has cracked or fallen away, call us for a roof survey. Getting the lead looked at before the next period of wet weather is the most cost-effective step you can take.
Before you agree to lead work, it is worth asking the following:
A roofer who answers these questions clearly and specifically is worth trusting with the job. Vague answers about lead work usually mean vague workmanship.
Lead flashing failures do not fix themselves. A hairline crack in the mortar becomes a gap; a gap lets water in repeatedly over months; repeated wetting of timber leads to rot; rot means a bigger repair bill. The earlier you deal with a failed flashing, the smaller and cheaper the job is likely to be.
If you have noticed a damp patch inside the house near a chimney breast or the corner of a dormer, or if you can see from the ground that mortar has fallen out from around the flashing, get it looked at now rather than waiting for the next season of heavy rain to make the problem worse.
Call us to arrange a roof survey in Lakenheath and we will tell you exactly what is needed, what lead code is appropriate, and what the job will cost before any work starts.
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