Lead Work in Cambridge

Expert Lead Work
in Cambridge

Why Lead Fails - and Why It Matters

Lead is the material that sits between your roof tiles and the vertical surfaces they butt up against - chimney stacks, parapet walls, dormer cheeks and bay roof junctions. When it works, it keeps water out of those joints silently and indefinitely. When it fails, water tracks down inside the wall or into the ceiling below, often weeks before you notice any staining indoors.

The tricky thing about lead failure is that the roof tiles themselves can look perfectly intact. A homeowner sees no broken slates, no obvious gaps, and assumes the roof is fine. The leak is actually at the flashing, not the tiles, and a roofer who does not check the leadwork specifically can easily miss it.

The Warning Signs to Look For

You do not need to get on the roof to spot early signs of lead failure. Start from the ground and look at the chimney or dormer carefully. Common visible indicators include:

• Lead that has slipped downward and is no longer tucked into the mortar joint above it
• Visible gaps between the lead and the brickwork it was bedded against
• Lead that has split or cracked - usually visible as dark lines running across the surface
• White staining or efflorescence on brickwork just below the flashing line
• Mortar pointing that has fallen out of the step flashing chase, leaving the lead loose
• Bubbling or peeling paint on an interior ceiling or wall directly below a chimney breast or dormer
• A persistent damp patch that appears after rain but dries between wet spells

Any one of these signs is worth investigating. More than one together usually means water has already been getting in, and the sooner you have it looked at the less damage there is to put right.

What Actually Causes Lead to Fail

Lead does not fail overnight. There are several causes, and understanding them helps you judge whether a repair will hold or whether replacement is the better call.

Thermal movement. Lead expands and contracts with temperature changes. Over time, if the lead sheets were fitted in lengths that are too long, or without the correct fixing clips to allow movement, the metal works loose or splits. Correct installation accounts for this by using shorter lengths and leaving expansion gaps at overlaps.

Mortar failure. Step and cover flashings are typically held in a chased joint in the brickwork and sealed with mortar pointing. That pointing can crack and fall out after years of freeze-thaw cycles. Once the pointing goes, the lead is no longer held firmly and water can bypass it at the top edge.

Age and fatigue. Even well-installed lead has a finite life. Code 4 lead (the weight most commonly used on chimney flashings) typically lasts several decades when fitted correctly, but flashings on older properties may have had several cycles of bodged repairs using mastic or bitumen tape before the lead itself was ever addressed. Those patches fail faster than the original lead and mask the underlying issue.

Poor original installation. If lead was dressed too flat, or the soakers beneath the step flashings were omitted or fitted incorrectly, no amount of repointing will fix the underlying problem. This is particularly common on properties where previous repair work was carried out cheaply.

Vandalism and theft. Lead theft remains a risk on properties with low-pitched roofs or accessible flat-roof sections. If you notice missing sections rather than degraded ones, the fix is replacement with correctly lapped new lead, ideally secured against future removal.

What Good Lead Work Covers

Leadwork is not a single task - it covers several distinct elements depending on where the roof meets another surface:

• Chimney flashings - the front apron, two side step flashings and the back gutter between the chimney and the slope behind it
• Soakers - small individual pieces of lead that interleave with each course of slate or tile at a chimney or abutment
• Valley linings - continuous lead sheets in the internal angle where two roof slopes meet
• Dormer flashings - covering the cheeks, the sill and the junction at the top where a flat dormer roof meets the main slope
• Parapet and wall flashings - where a roof meets a vertical wall on an extension, bay window or lean-to

A proper survey of any of these elements should look at whether the lead itself is sound, whether the fixing and pointing are intact, and whether the underlying structure - tile battens, roof decking, brickwork - has been affected by any water that has already got in.

When to Repair and When to Replace

A small area of lead that has slipped or lost its pointing does not necessarily need to be stripped and replaced. If the lead sheet itself is in sound condition and the correct thickness for its location, re-dressing it, re-chasing it into the brickwork and pointing with fresh mortar is a reasonable and lasting repair.

Replacement makes more sense when the lead has cracked or split in multiple places, when previous mastic patches have failed repeatedly, or when the original installation was too short on material to do the job properly. Replacing a full chimney flash set on a standard stack typically costs in the range of £300 to £600 depending on access and the number of elements involved. Valley replacements vary more widely with length and pitch.

If you have had the same area repointed or mastic-patched more than once without a lasting result, ask specifically for the lead itself to be assessed, not just the pointing.

Lead Work in Cambridge - Getting It Checked

Haverhill Roofers covers Cambridge and the surrounding area including nearby towns such as Newmarket and Saffron Walden. If you have spotted any of the warning signs above, or if your property has a chimney, dormer or extension roof junction that has not been looked at in several years, call us to arrange a roof survey focused on your leadwork.