Most people’s relationship with their roof begins the day it stops working. A brown ring appears on a bedroom ceiling, or a patch of wallpaper starts to lift, and suddenly a part of the house that has been quietly doing its job for eighty years demands attention, money and a scaffold.
That is an expensive way to discover a problem. Almost every serious roofing failure announces itself months or years in advance, usually in ways that are visible from the pavement if you know what you are looking at. The gap between noticing a slipped tile and dealing with a rotten roof deck is often the difference between a morning’s work and a five-figure invoice.
What is actually up there
Understanding the warning signs is easier once you know what a typical roof is made of. Across much of London the housing stock is late Victorian or Edwardian, which usually means a pitched roof clad in slate or clay tile, fixed to timber battens, laid over rafters, with lead used to seal the awkward junctions — around chimneys, in valleys where two roof planes meet, and at abutments where a roof runs into a neighbouring wall.
None of those materials fails at the same rate. Welsh slate can comfortably outlive the person who paid for it. The nails holding it on cannot. This is a phenomenon roofers call nail sickness, and it is the single most common reason a perfectly sound-looking Victorian roof starts shedding slates for no obvious reason: the slate is fine, the fixing has corroded away beneath it. Likewise, the mortar bedding the ridge tiles and the flaunching around a chimney pot has a working life measured in decades, not centuries, and it tends to go long before anything around it.
So the useful mental model is not “how old is my roof” but “which component is nearest the end of its life.”
The five things worth looking for
Slipped, cracked or missing units. Stand across the road, ideally with binoculars, and look along the roof plane. It should read as a regular grid. Anything that has dropped out of line, cracked, or gone missing entirely is a breach, and the tile below it is now taking water it was never designed to take. One slipped slate is a small job. One slipped slate ignored for two winters is often several.
A ridge line that is no longer straight. Sight along the top of the roof. A gentle sag in an old property can be historic settlement and nothing to worry about; a new dip, or one that has visibly worsened, suggests something structural underneath. While you are looking, check whether the mortar between the ridge tiles is intact or whether you can see gaps and crumbling.
The chimney. Chimneys cause a wildly disproportionate share of roof leaks, because they involve three separate things that all degrade: the flaunching on top, the pointing in the brickwork, and the lead flashing where the stack meets the roof. Lead that has lifted, split at a fold, or pulled out of its mortar joint will let water straight in, and because the water then tracks along a rafter before it drops, the damp patch on your ceiling can appear metres from the actual fault.
The gutters. Water spilling over the front edge of a gutter during rain is telling you something is blocked or the fall is wrong. It matters more than it looks: water running down a wall for years will saturate the brickwork, and on a rendered or painted elevation you will usually see a vertical stain or a patch of green growth marking the spot. Sagging sections, split joints and daylight between the gutter and the fascia board are all worth acting on before the fascia itself starts to rot.
Flat roofs on extensions and dormers. These have their own vocabulary of failure. Ponding water that is still sitting there two days after rain means the falls are inadequate. Blistering, splitting at the upstands, and any lifting at the edge trim are all end-of-life signals. Felt roofs laid in the eighties and nineties are, as a category, now well past their intended service life.
The signs from inside
The loft is the most honest room in the house. Go up on a bright day with the light off and look for daylight coming through the roof covering — pinpricks are normal on an old slate roof, larger patches are not. Then look at the timber: dark staining on rafters or battens shows where water has been getting in, and if the stain is damp to the touch, it is still getting in. A musty smell, white salt deposits on chimney brickwork, or insulation that is matted and darkened in one area all point to the same conclusion.
Repair or replace
This is where most homeowners get stuck, and where the advice varies wildly depending on who is giving it. The honest answer depends on three things: the proportion of the covering that is failing, the condition of the battens and underlay beneath it, and how long you intend to stay.
If a handful of slates have slipped on an otherwise sound roof, repair is straightforward and sensible. If a roofer lifts a section and finds the battens are soft, the felt has perished, and the nails are corroding across the whole plane, then patching becomes a rolling annual cost that eventually exceeds the price of doing it properly once. A reputable contractor will show you what they have found rather than asking you to take their word for it, and will explain why they are recommending what they are recommending.
The other factor is access. A large share of the cost of any roof work is getting a person safely up there, which means that combining jobs — repointing the chimney at the same time as replacing the flashing, for example — is materially cheaper than doing them in separate years.
Getting it looked at properly
An inspection is not the same as a quote. A proper survey means someone physically getting up to the roof, checking the loft from inside, and reporting what they find with photographs, rather than glancing at it from the ground and naming a figure. Any established firm offering roofing services in East London should be willing to do that without obligation, and to give you a written scope explaining exactly what is being replaced and what is being left.
Two practical points on timing. First, book non-urgent work outside the autumn rush, when every roofer in the city is fielding storm calls and prices harden accordingly. Second, if you have an active leak, the immediate priority is containing the water inside — move what you can, put a container under the drip, and if a ceiling is bulging, pierce it deliberately in one spot to let the water out rather than letting it collapse. Then call someone.
A roof is the one part of a house where deferred maintenance compounds fastest, because every month of water ingress damages something that was previously fine. Looking up occasionally is free.
