8 Signs You May Have a Roof Leak (UK Guide)

A roof leak can start as a small damp patch and quickly turn into serious damage if ignored. Knowing what warning signs to look for can help you catch issues early and avoid costly repairs.

Here are the eight most common signs of a roof leak and what each one usually means.

1. Water Stains on Ceilings or Walls

Brown or yellow stains on ceilings and high-level walls are classic indicators of a leak. Even if the stain seems small or old, it often points to water entering during heavy rain and slowly spreading through insulation or plasterboard.

2. Mould or Mildew on Exterior Walls

Black spotting or green algae on exterior walls can suggest moisture behind the brickwork. This sometimes happens when water enters through a failed flashing, gutter leak or cracked roof tile and travels down the wall cavity.

3. Damaged or Loose Flashings

Flashings around chimneys, skylights and parapet walls are common failure points. Cracked mortar, loose leadwork or gaps around these edges almost always lead to water ingress during storms and high winds.

4. Light Visible in the Loft (Shiners)

If you can see sunlight coming through the roof when standing in the loft, there’s a direct gap in the covering. Even tiny openings can allow rain-driven water inside, especially during winter storms.

5. Missing, Cracked or Curled Tiles

Tiles that have slipped, cracked or lifted create exposed pathways for water. If you can see bare underlay from the ground, or if tiles look uneven, a leak is likely to follow during prolonged rainfall.

6. Damp Patches or Water Trails in the Loft

Moisture on rafters, insulation or loft boards usually indicates slow water penetration. Check during or immediately after rain - fresh leaks are often easy to spot because timber will appear darker or feel damp to the touch.

7. Peeling Paint or Blistering Plaster

Inside the home, bubbling plaster or flaking paint around ceilings, corners, or window junctions can show that moisture is travelling internally. This often accompanies a recurring leak that has been active for some time.

8. Blocked Gutters or Overflowing Outlets

A blocked downpipe or valley gutter causes water to back up and overflow into the roof structure. Overflowing gutters during rain are one of the simplest yet most overlooked causes of internal leaks.

Worried You May Have a Leak?

If you’ve noticed any of the signs above, it’s best to get the issue checked early - leaks rarely stay small.

For fast help, see our Leaking Roof Repairs page here:

Want a Full Breakdown of Causes & Repair Costs?

For a deeper guide covering emergency fixes, cost ranges and when to call a professional, read: Leaking Roof in the UK? Causes, Emergency Fixes & Repair Costs