Lead Work in Grantchester - What to Do While You Wait

Expert Lead Work
in Grantchester

What Lead Flashings Do and Why Failure Matters

Lead flashings seal every junction where your roof meets a vertical surface - the base of a chimney stack, the sides and front of a dormer, parapet walls, and anywhere a flat roof abuts a wall. When a flashing fails, water does not necessarily come straight through the ceiling below it. It often tracks sideways along a rafter, runs along the top of a ceiling joist, and appears some distance from the actual entry point. By the time you see a stain, water may have been finding its way in for weeks.

That is why acting promptly matters and why protecting the interior while you wait for proper repairs is not an overreaction. At the same time, the temptation to fix it yourself - or to let someone apply a quick patch that delays a proper repair - is worth resisting.

The Basics of Lead Work on a Roof

A correctly installed lead flashing involves cutting sheet lead to the correct Code for the application. Code 4 (1.80mm) is standard for step and cover flashings on a chimney or dormer. Code 5 (2.24mm) or Code 6 (2.65mm) is used for wider back gutters, flat roof upstands and more exposed applications. The lead is dressed to the profile of the surface it seals, fixed with lead clips, and tucked into raked mortar joints in the brickwork before the joints are re-pointed.

Each length of lead needs to be short enough to allow thermal movement. Lead expands in warm weather and contracts in cold. A length of more than about 1.5 metres needs a separate piece with a proper lap or drip between them. When this is not done, the lead splits - not because it has failed through age but because the installation did not allow for the way lead behaves.

Immediate Steps to Protect Your Home

If you have an active leak, the first priority is limiting damage to the interior while you wait for the roofer.

• Catch the water. Place buckets, bowls or trays under any active drip. Lay down towels or plastic sheeting to protect floors and furniture.
• Leave a bowed ceiling alone. If a section of ceiling plasterboard is visibly bulging with trapped water, keep everyone out of the room and do not poke, prod or pierce it - it can come down without warning.
• Move valuables, electrics and soft furnishings. Water and electricity are the main risk. If there is any possibility of water reaching a light fitting or a socket, switch off the circuit at the consumer unit and do not restore power until the area is dry and has been checked.
• Note where the leak appears and when it is worst. Tell the roofer whether the drip is continuous or appears only during or after rain, and whether it is worse in certain wind conditions. This information helps narrow down the entry point, which is especially useful when the leak appears some distance from the flashing.

What Not to Do Yourself

The desire to do something while you wait is understandable, but some common DIY responses to a failing flashing cause problems that make the roofer's job harder and cost you more in the long run.

Do not apply sealant, mastic or bitumen paint to the lead. It is almost impossible to get these products to form a reliable bond directly to lead, and they cannot accommodate the thermal movement of the metal. They will crack within a season. The greater problem is that once sealant has been applied, a roofer needs to clean it all off before they can assess the condition of the lead and dress it properly. That adds time and cost to a job that was otherwise straightforward.

Do not attempt to re-press or re-dress the lead yourself. Lead that has lifted or pulled free from a mortar joint can look as though it simply needs pushing back. But lead that is forced back without being properly re-dressed will not lie flat and will not seal the joint. Bending and rebending the same section of lead also weakens it at the fold, making a split more likely at that point.

Do not seal the flashing from inside the loft. Some homeowners apply sealant or tape to the underside of the felt or to the rafters in the loft space to try to divert or stop water. This conceals the entry point, makes it harder to trace the source, and allows water to continue saturating the roof structure out of sight.

Do not get on the roof without the right equipment and experience. Falls from roofs are a serious cause of injury. Loose, wet or frost-covered surfaces are particularly dangerous. If you want to look at the lead from closer, use binoculars from a window or from the ground rather than climbing onto the roof.

What to Tell the Roofer When They Arrive

The more information you can give, the more efficiently the roofer can identify the problem. It helps to know:

• When the leak first appeared and whether it followed a specific weather event.
• Where the damp shows internally and the direction it seems to track.
• Whether the flashings have had any previous work done to them - repairs, sealant applied, or re-pointing.
• Whether the chimney is in use. An active flue expands and contracts more frequently due to heat, and that affects the rate at which mortar pointing around flashings deteriorates.

What the Repair or Replacement Will Involve

A roofer attending a failed lead flashing will need to establish whether the lead itself has failed or whether the mortar pointing has given way and the lead is still sound. Those two findings lead to different remedies. Re-pointing a sound flashing is a shorter job. If the lead needs replacing, the roofer will remove the old material, prepare the substrate, cut and dress new lead to the correct Code, bed it into the mortar joints, and point up on completion.

On a chimney stack, soakers between each slate or tile course are part of a proper installation. If the original soakers were omitted or were undersized, that needs to be rectified at the same time as the flashings. Replacing only the visible lead without checking the soakers is a partial repair that will not hold.

Re-flashing a standard chimney stack typically costs in the region of £400 to £900, depending on the size of the stack and the amount of access work involved. A dormer cheek or flat roof abutment is often less, depending on the length of the run and the condition of the surrounding materials. Always ask for the scope to be explained clearly before work begins, including what Code of lead will be used and how the expansion issue will be handled.

Arranging a Survey for a Failed Flashing

If you have a leak that you believe is coming from a failed flashing, call a roofer to arrange a survey. A good roofer will trace the entry point, explain what needs doing, and carry out the work properly so the problem does not return next winter.