1. Failed lead flashings
The single most common cause of roof leaks we see. Lead around chimneys and abutments hardens and cracks over 30–40 years. Water tracks down the chimney breast and appears as a stain on the bedroom ceiling.
The permanent fix is to strip out the old lead (or worse, cement fillet) and re-dress in Code 4 or Code 5 milled lead.
2. Slipped or missing tiles
Nail sickness — corrosion of the fixing nails — causes tiles to slide out of place. One slipped tile is a five-minute repair. A dozen slipped tiles is the sign of a bigger problem.
Replacement with copper or stainless fixings is the permanent solution.
3. Blocked valleys and gutters
Moss, leaves and silt back up water so it overflows sideways under the tiles instead of running away. A £150 annual gutter clear prevents thousands in ceiling damage.
4. Cracked mortar bedding
Ridge and hip mortar breaks down over 30–50 years. Once cracked, wind lifts tiles and water tracks in. Modern dry-fix systems solve the problem for good.
5. Perished underlay
Older bitumen underlay perishes and no longer sheds water that gets past the tiles. Often the only signal is a stain that appears in one place regardless of the weather — because it's tracking down a rafter from further up.
6. Poorly detailed rooflights and dormers
Rooflights installed without proper flashings, or dormers with cement fillets instead of dressed lead, leak persistently. Rebuilding the detail in lead is the permanent fix.
Diagnosing your leak
Water rarely appears directly below its entry point — it tracks along rafters and down internal walls before showing itself. A proper inspection from the outside, ideally in the rain, is worth more than an hour spent in the loft with a torch.