Lead Work in Cottenham

Expert Lead Work
in Cottenham

What lead work involves

Lead is used to seal the points on a roof that are most vulnerable to water entry: the junction of a chimney with the main slope, the cheeks and head of a dormer, the sides and back of a bay window roof, the upstand where a flat roof meets a house wall, and the valleys between two pitches. When lead is correctly fitted and hand-dressed to BS EN 12588 standard, it forms a durable, watertight seal at each of these positions. When it fails, leaks follow quickly and damage to timbers and ceilings can build up before you even notice.

All the lead work we carry out is dressed on site by hand. We cut and shape each section to suit the profile of the specific roof and fix it using the correct method for the position, so it can expand and contract freely with temperature changes without splitting or lifting.

Why aftercare matters with lead work

Good lead work, installed correctly, is a long-lasting material. But even well-fitted lead can develop problems over time if simple maintenance is neglected. The mortar that holds the flashing into the wall joint can shrink and crack. Debris can build up in valleys and cause water to back up behind a flashing. Nearby vegetation can grow against lead and hold moisture against it. None of these problems are difficult to deal with if caught early, but left alone they will shorten the life of perfectly good lead work and eventually cause leaks.

The good news for homeowners in Cottenham is that the maintenance involved is mostly visual: knowing what to look for, looking for it at the right times, and acting quickly when something needs attention.

How often should you check your lead work?

A visual inspection of the roof twice a year is a sensible routine for most properties. The two best times are late autumn, after the leaves have fallen and before the worst of the winter weather, and late spring, when you can see whether frost or winter winds have caused any movement. You do not need to go onto the roof to do this: a good pair of binoculars and a look from ground level, combined with a check of the loft space for any signs of damp, will show up most developing problems before they become serious.

You should also check after any notable storm, particularly if there has been significant wind. Wind can lift the edge of a flashing that has already started to part from the wall, turning a minor problem into a major one overnight.

What to look for

When inspecting lead work visually, these are the signs that something needs attention:

• Lifted or open edges. The top edge of a flashing should sit tightly into the mortar joint. If it has lifted away from the wall even by a few millimetres, rain can run behind it. This is often visible from below on a chimney stack.
• Cracked or crumbling mortar at the top of the flashing. The repointing that holds the flashing into the chase is not permanent. Expect to repoint every ten to fifteen years on most properties, though harder mortar mixes fail sooner and softer lime mortars tend to last longer.
• White staining or streaking on the lead surface. A degree of white patination is normal and actually helps protect the lead. But heavy white deposits at joints or overlaps can indicate water is finding a path it should not.
• Splits or cracks in the body of the lead. These are most common in older lead that has been re-dressed several times and has become work-hardened. A crack that has opened enough to let daylight through will let water through too.
• Debris build-up in valleys or behind chimney back gutters. Leaves, moss and grit collect in the low points of a lead valley and around chimney back gutters. This debris holds moisture and, over time, can cause water to back up behind the flashing rather than running clear.
• Moss or vegetation growing against the lead. Moss and overhanging branches that press against lead hold moisture against the surface and accelerate corrosion in the long run. They also tend to lift the edge of flashings as they grow.

Simple maintenance that makes a real difference

Most of the maintenance that extends the life of lead work requires no tools and no time on the roof. Keeping gutters clear means water does not back up and overflow onto flashings below. Cutting back any overhanging branches removes the source of leaf debris that collects in valleys and gutters. If you have a flat roof with a lead upstand, keeping the surface of the flat roof clear of standing water and debris reduces the load on the lead joint.

For mortar repointing, this does need a roofer. The process involves raking out the old mortar from the chase to a depth of about 25mm, pressing the lead edge back firmly into the joint, and repointing with a mortar of the right mix for the brickwork. On period properties this typically means a lime mortar; on modern brickwork a sand and cement mix is usually appropriate, though not too strong a mix or it will crack again quickly.

If you notice moss growing extensively across the roof above lead flashings, treating it before it reaches the lead itself is worth doing. Moss can be treated with a proprietary biocide that kills it without the need to physically scrub the tiles, which can disturb the tile bedding and the flashings themselves.

When to call a roofer rather than wait

There are some situations where you should not wait for the next scheduled inspection. If you see water staining on a ceiling below a chimney, dormer or flat roof abutment, that is a sign the lead has already failed and water is entering. Call a roofer promptly; the longer water is in contact with roof timbers, the greater the risk of rot. The repair will also be simpler and cheaper if the timbers are still sound.

If after a storm you can see from ground level that a section of flashing has pulled away from the wall or been displaced, that is also worth dealing with quickly. An open flashing in winter, with frost and rain, will cause more damage than the same problem dealt with in autumn.

Aftercare and the lifespan of lead work

Correctly specified and installed lead, kept clear of debris and repointed as the mortar requires, can remain in service for many decades. The lifespan depends significantly on the code of lead used, the quality of the original installation, and whether routine maintenance is carried out. Code 4 step flashings around a chimney, properly maintained, can realistically last forty years or more. Lead valleys with heavier code 5 or 6 material can last longer still.

What cuts that lifespan short is almost always one of three things: the wrong code of lead used originally, sections fitted too long so they crack under thermal movement, or mortar joints left to open up until rain has been entering behind the flashing for years. Regular checks stop the third problem from happening.

Book a lead work inspection in Cottenham

If you have not had your lead work inspected for several years, or if you have noticed any of the signs described above, call Newmarket Roofers to arrange a roof survey. We will inspect all the lead work on your property, tell you what condition it is in, identify any areas that need attention now, and advise on what to watch for going forward.