If you have a persistent leak around a chimney, dormer or valley in Attleborough, failing leadwork is the most likely cause.
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Lead is the material roofers use to seal every junction where a roof meets a vertical surface - a chimney stack, a dormer wall, a parapet, a skylight kerb, or the valley where two roof slopes meet. Correctly installed, it flexes with the building through summer heat and winter frost without cracking. When it fails, water gets in along the very joints it was supposed to protect, which is why roof leaks caused by failed leadwork can be surprisingly difficult to trace from inside the loft.
Leadwork fails for several reasons. Age is the most obvious: lead laid more than 50 years ago is often past its serviceable life, especially if it was laid in long uninterrupted runs that have cracked from thermal movement over decades. Poorly pointed mortar in the step and cover flashings is another common problem - the lead itself may be sound, but once the mortar fillet behind it opens up, rainwater tracks under the flashing and into the roof structure. On valley gutters, a build-up of moss, debris and standing water accelerates the problem further.
Bodge repairs with roof sealant or mastic are a temporary fix at best. They mask the symptom without addressing the underlying joint, and when they fail - usually within a season or two - you are back to square one, often with more water damage than before.
This section walks through a typical leadwork job in Attleborough from the initial inspection right through to clearing up. Every job is different in its detail, but the broad sequence is consistent, and knowing what to expect helps you judge whether the work is being done properly.
We start at ground level, looking at the visible condition of any lead flashing, valley or apron from the outside. Staining on brickwork below a flashing, open mortar joints in a stepped flashing, or lead that has slipped, buckled or developed a visible split are all signs we can often spot without going on the roof. This gives us a starting point before we go up for a closer look.
On the roof, we check the full extent of any lead detail in the area of concern. We look at how the lead is dressed - whether it sits properly against the masonry and has adequate overlap - and how the mortar pointing behind cover flashings is holding. We check for any signs of lifting at the edges, crazing of the lead surface (a sign of old age), or areas where a previous repair has been applied over the original. We also check the surrounding tiles or slates for any that have shifted, since a slipped tile near a flashing can redirect water in unexpected ways.
We tell you what we find honestly: whether it is a small repair to a section of flashing, a full replacement of a chimney detail, or a valley that needs stripping back and re-lining. We do not recommend more work than the situation genuinely calls for.
For chimney stacks and dormer flashings, we use scaffolding or a tower as the job demands. Working safely on a pitched roof around a chimney is not a job for a ladder alone, and any roofer who tells you otherwise is cutting corners you should not accept. Once access is set up, we protect the surrounding area - gutters, paintwork, any planting below - so that offcuts and old material do not cause damage on the way down.
Depending on what we found in the inspection, this may mean carefully removing individual sections of flashing or taking out an entire valley lining. Old lead can be recycled, which means the scrap value partially offsets the material cost of the new lead. We take care at this stage not to disturb surrounding slates or tiles unnecessarily - every tile we lift and replace is an opportunity for a mistake, so we keep the footprint of the strip-out as small as the job allows.
When stripping lead from around a chimney stack, we also inspect the masonry. Spalled brickwork or open mortar joints in the stack itself need attention before new lead goes on - otherwise water will find a way in through the stack itself regardless of how good the new flashing is. If repointing is needed, we carry that out before we begin fabricating the new lead work.
Lead for roofing is sold in rolls by code number, which indicates the thickness. Code 3 and Code 4 are commonly used for small flashings and soakers. Code 4 and Code 5 are standard for chimney and dormer flashings. Code 5 and Code 6 are used for valley gutters, flat roof edges and parapet gutters where the lead is asked to carry standing water for any period.
Using the correct code for the detail matters. Thin lead on a valley that holds water will fail earlier. Thick lead on a small soaker flashing is unnecessary and adds cost. We cut lead to the correct length for each section - individual sections should not exceed 1.5 metres in a single run for most chimney and dormer flashings, to allow for thermal movement without buckling. Longer runs need proper expansion joints built in.
Dressing means shaping the lead to fit the profile it needs to cover. For a stepped flashing against a chimney or dormer, each step is cut and folded by hand to follow the mortar courses precisely. The lead is worked cold using a bossing mallet and dresser, or a lead dresser tool, to form the exact profile without thinning the material. Good dressing work is visible in the even, close-fitting finish where the lead meets the masonry - there should be no gaps, no puckering and no splits in the material at the folds.
Lead flashings are secured by pressing the top edge into the mortar joint (a raked-out bed joint in the masonry), then securing it with lead wedges driven into the joint at regular intervals. The joint is then pointed with fresh mortar or a proprietary lead sealant. This is the detail that most failed repairs get wrong - the lead is pressed in and pointed, but the wedges are skipped or the pointing is applied over old friable mortar rather than into a properly prepared joint. Within a season, the mortar shrinks away and the flashing lifts at the top edge.
For soakers - the individual lead pieces that tuck under each slate or tile at a junction - no mortar is used. They are lapped correctly under each course and held by the weight and overlap of the tiles themselves. Getting soaker length right (they need to extend far enough up the roof slope) is what separates a properly installed detail from one that will leak in heavy rain.
Once the new lead is in place and any mortar has had time to harden, we carry out a visual check of every section: edge dressing, joint width, lap distances, pointing condition. If accessible, a water test can confirm the detail is watertight before we leave the roof. We also check that no tiles or slates disturbed during the job are loose, cracked or missing.
Old lead, tile offcuts and mortar debris come off the roof and are loaded for disposal or recycling. We clear gutters of any debris that has come down during the job. The surrounding area is left as we found it.
Chimney leadwork is one of the more involved details on a domestic roof because it has several separate elements that all need to work together. A typical chimney has a back gutter (behind the stack where the roof slope meets the chimney), side step flashings that follow the roof slope up both sides of the stack, and a front apron flashing over the lower edge. On older stacks, there is sometimes also a sounder course of lead lining the top of the stack pot.
The back gutter is the section most likely to cause problems. It sits in a position where debris collects and where water from the main roof slope concentrates. A properly formed back gutter has upstands at both sides, a fall to drain water away, and an adequate depth to handle heavy rain without overflowing behind the flashing. If it is undersized or has lost its fall, it holds water, and water sitting against the masonry eventually finds its way through.
Typical costs for a full chimney leadwork replacement on a standard domestic stack in Norfolk run from around £600 to £1,200 depending on the size of the stack, the lead code specified, whether scaffolding is needed and what condition the masonry is in. A repair to a single failed section of flashing costs considerably less.
A lead valley is the channel formed where two roof slopes meet. It carries a significant volume of water in heavy rain and is therefore one of the most important details to get right. Lead valleys can fail at the joints between sections, along the edges where the lead has been dressed up under the tiles, or at the lower end where it discharges into the gutter. Mortar fillets alongside the valley - sometimes used as an alternative to properly dressed lead - crack with age and are a frequent source of leaks.
When re-lining a lead valley, we strip the existing material, check the timber boarding or substrate underneath for rot, and replace any damaged sections before laying the new lead. Valley lead should be Code 5 or 6 as a minimum. Typical costs for re-lining a valley in lead range from around £400 to £900 for a single valley, depending on length and access.
Dormer windows introduce multiple junctions that all need flashings: the cheeks (sides), the head (top), and often a lead apron or gutter at the base of the dormer cheeks. Timber-framed dormers are particularly prone to problems if the lead at the junction between the dormer cheek and the main roof slope has not been correctly dressed or has opened up as the timber has moved over time. We treat dormer leadwork as a whole detail rather than replacing individual sections in isolation, since a repair to one junction while leaving a failing adjacent section will simply move the leak.
Lead is also used at the edges of flat roofs - as a drip edge, as an upstand flashing where a flat roof meets a wall, or as the lining of a parapet gutter. These details are exposed to standing water for longer periods after rain, which is why the code of lead specified matters more here than on pitched roof flashings. Parapet gutters in particular should be lined in Code 6 lead with properly formed drips to control how water moves along the gutter length. A common problem is that the fall in a parapet gutter has been lost over time as the structure settles, leaving water standing against the back wall upstand and eventually tracking through.
For small flat roof areas such as a bay top or a garage, lead is sometimes specified as the main covering rather than just the edge details. It is a durable choice for small areas. However, for larger flat roof areas, modern torch-on felt or EPDM rubber membranes are more practical and more cost-effective per square metre. We can advise on which system suits the area and detail you have.
Before accepting a quote for leadwork, it is worth asking the following:
A roofer who can answer these questions clearly and consistently is one who knows the work. Vague answers about "making it all good" without any specifics on materials or method are a warning sign.
Wymondham Roofers carries out leadwork repairs and replacements in Attleborough and the surrounding area. Call us to arrange a roof survey if you have a suspected leak or can see signs of failing leadwork from the ground.
If you can see a problem or you have had a leak that has not been properly diagnosed, arrange a roof survey before any work begins. We will tell you what we find, what needs doing and what it is likely to cost - before any work begins.
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Call any time. Calls are answered day and night and passed straight to our roofers.
