A damp patch on the ceiling is enough to ruin a week. The good news is that most roof leaks come from a short list of causes, and you can check several of them yourself before you ring anyone. Here are the nine I see week in, week out across Chesterfield and north Derbyshire — and the one that isn't a leak at all.
1. A slipped, cracked or missing tile
The obvious one, and often the easiest to spot. A tile that's slid down, cracked across, or gone entirely leaves the felt beneath exposed. You can often see a missing tile from the ground with binoculars — a gap in the line where there shouldn't be. This is a straightforward repair, usually £150 to £450.
2. Failed mortar bedding on the ridge or verge
The ridge tiles along the top and the verge tiles at the gable edge are held in place with mortar. On older roofs that mortar crumbles — freeze-thaw through a Derbyshire winter does for it — and the tiles shift, letting wind-driven rain in. Mortar debris collecting in the gutters below the ridge is the tell. Ridge tiles that rock when pushed mean the bedding underneath has failed.
3. A perished flashing at a chimney or abutment
Where a roof meets a chimney or a wall, the join is sealed with lead flashing. Over decades the lead perishes, pulls away, or was never done properly in the first place. A damp patch on the chimney breast inside, or a brown stain where the stack meets the roof, points here. A mortar fillet cracked along the join is a sign someone did it on the cheap — it should have been lead.
4. A failed valley
The valley is where two roof slopes meet, and it carries a lot of water. If the valley lining perishes or the edges let water behind, it leaks — and it leaks seriously, because valleys concentrate rainfall. A dark stain running down the valley line on the underside, or in the loft, is the warning.
5. Nail fatigue on a slate roof
On the Victorian and Edwardian slate roofs across Chesterfield centre and Whittington Moor, the nails holding the slates rust through after a century. The slates themselves are sound, but they start sliding out of line and lifting in the wind. Once that's happening in more than one place, it's a re-roof, not a repair — you can't re-nail sound slate onto rotten fixings for long.
6. Cracked or perished flaunching on a chimney
The flaunching is the mortar cap around the chimney pots that sheds water. When it cracks — and it always does eventually — water runs straight down inside the stack. It's one of the most common sources of a "roof" leak that's actually a chimney leak. Cracks visible around the pots, or a damp chimney breast, are the signs.
7. A blocked or split valley gutter or box gutter
Flat-roofed sections, dormers and parapets often have box gutters that carry water away. If they split, or block with leaves and moss, water backs up and over the edge. A stain on the wall below a parapet or dormer is the clue.
8. Condensation — the one that isn't a leak
This catches people out. A patch on the ceiling, damp to the touch, that gets worse in cold weather — it's often condensation, not a leak. Warm moist air from the house hits a cold surface and condenses, mimicking a roof leak perfectly. Before you pay anyone to "find a leak", check: does the damp appear mostly in cold weather and clear in summer? Is the loft ventilation blocked? Is there an unlagged cold water tank or pipe nearby? If it's condensation, no amount of roof repair will fix it — you need ventilation, not a roofer. I'd rather tell you that on the phone than take your money finding nothing.
9. Perished felt under the tiles
On older roofs the bitumen felt under the tiles perishes and tears. Wind-driven rain that the felt would once have shed now reaches the loft. You'll see it in the loft as torn, hanging felt before you see it indoors.
What to do first
If water's actively coming in, move what's beneath it, put a bucket down, and if the water's near any electricals turn that circuit off at the consumer unit. Don't go up on the roof yourself — that's how people get hurt. Take a photo of the damp from inside and one of the roof from the ground, and ring. For an active leak we aim to get out same-day across Chesterfield and the villages.
The key thing, whatever the cause, is finding the source rather than patching the stain. Water tracks along battens and rafters before it shows on a ceiling, so the damp patch is rarely directly under the hole. We get up, trace it properly, and fix the cause — because a repair that doesn't is a repair you pay for twice.