Ely Roofers carries out lead flashing installation and repair for homeowners in Littleport, and this page covers how to look after your lead work once it has been fitted so it lasts as long as possible.
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Lead flashing is used to weatherproof the junctions between roof surfaces and vertical structures - chimneys, dormer cheeks, parapet walls, and the valleys where two pitched roof slopes meet. It is also used for upstands on flat roof sections where the roof deck meets a wall. When fitted correctly using code 4 or code 5 lead sheet dressed to British Standard, a lead flashing detail can last for many decades. The work we carry out in and around Littleport uses the correct code for each application and is fixed and pointed properly, not just laid in mastic.
Code 4 lead (1.8 mm thick) is the appropriate choice for most chimney step and cover flashings. Code 5 (2.24 mm) is used in valleys and wider horizontal applications where the lead spans more surface area and needs to be more resistant to thermal movement over time. Using the right code from the outset is one of the most important factors in how long the flashing will last.
Lead is a durable material but it is not completely maintenance-free. It expands and contracts with temperature - in direct summer sun the surface temperature of lead can rise significantly above air temperature, and it contracts again in winter cold. Over many years, this repeated movement works the mortar pointing out of the raking joints and can loosen fixing clips. A flashing that was perfectly sound ten years ago may have small gaps opening up today simply because the pointing has weathered out.
The masonry around flashings - chimney stacks, parapet copings, dormer frames - also moves slightly over time due to settlement, frost action and general weathering. This affects the joints the lead is pointed into. Keeping an eye on both the lead itself and the surrounding masonry is the key to catching small problems before they become leaks.
You do not need to get on the roof to carry out basic checks. From the ground, using binoculars if needed, look for the following:
Inside the house, check the loft space after sustained rain. Damp on the rafters or purlins near a chimney stack or at the eaves is a useful early indicator that a flashing detail is allowing water in before the problem is visible on the ceiling below.
Blocked gutters cause water to back up behind the fascia and can saturate the roof edge timbers. Where a flat roof lead edge or parapet flashing sits at gutter level, a persistently overflowing gutter can push water behind the lead upstand. Keeping gutters clear - at least twice a year in areas with overhanging trees - reduces the water load that lead edge details have to cope with.
Where a downpipe runs close to a chimney stack, check that it is not discharging against the brickwork or saturating the mortar joints around the flashing. A cracked or displaced downpipe is sometimes misread as a lead work failure because the damp pattern inside the house looks similar.
Moss on roof tiles near lead flashings is worth controlling. Heavy moss growth holds moisture against the surface it sits on and can grow into mortar joints, including the joints that hold lead pointing in place. Where moss is spreading from tiles onto the face of a chimney stack, it can dislodge the mortar bedding of step flashings over time. Roof cleaning treatments applied to the tiles can limit this, but avoid applying any biocide product directly to lead - some formulations can stain or react with the surface.
Lichen on lead itself is generally harmless and does not indicate the lead is failing, but it can make surface cracks harder to spot during a visual inspection.
Some situations should not be left until your next routine check:
A maintenance inspection of lead work on a chimney stack involves getting onto the roof and checking each section of flashing in turn - the step flashings up both sides of the stack, the cover flashing, the back gutter behind the stack, and the front apron. A good lead worker will check the condition of the lead itself, the state of the mortar pointing, the clips and fixings, and the surrounding masonry. Any section that is loose is re-dressed and re-pointed. Missing mortar is raked out and replaced. This kind of visit, carried out periodically, is what extends the working life of a correctly installed lead detail well beyond what an unmaintained one would last.
Typical costs for a maintenance visit and re-pointing of chimney flashings are modest compared to a full replacement - re-pointing and re-dressing without replacing the lead commonly falls in the £150-£350 range, depending on the size of the stack and what is found. Full lead replacement on a standard domestic chimney, when it does become necessary, is typically in the range of £500-£900. Keeping on top of maintenance avoids reaching the point of full replacement prematurely.
If you have not had your lead flashings checked in several years, or if you have noticed any of the signs described above, call Ely Roofers to arrange a roof survey. We cover Littleport and the surrounding area from our base in nearby Ely. Catching a small problem early is nearly always cheaper than dealing with water damage after a failure.
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