In short
Water damage usually appears far from where the water enters. Before repairing, trace the source: roofs and their drains, bathrooms and kitchens, tanks and pipes, window and facade joints, and moisture rising from the ground. Repair the entry point and the damage it caused, then check the result, or the stain returns.
Key points
- The stain shows where water ends up, not where it enters.
- Roofs, wet areas, tanks and pipes, facade joints and the ground are the usual sources.
- Trace with observation, timing (after rain, after showers, constant) and, where needed, testing.
- Fix the entry point first, then repair the concrete, plaster and finishes it damaged.
A damp patch on a ceiling is where water has ended up, not necessarily where it got in. Water travels along slabs, inside walls and through service ducts before it shows. Repairing the stain without finding the source is the most common reason water damage comes back.
The usual sources
- Roofs: failed or ageing waterproofing, blocked drains, damaged upstands at parapets, and penetrations for pipes and equipment.
- Wet areas: bathrooms and kitchens with failed waterproofing under tiles, leaking traps and joints, and cracked grout.
- Tanks and pipes: roof and ground tanks, supply and drainage pipes inside walls and slabs.
- Facades: joints around windows and doors, cracks in render, and the junctions of different materials.
- The ground: moisture rising into walls where the damp-proofing is missing or damaged.
Tracing the source
When does the damp appear? Only after rain points to the envelope; after showers, to a wet area; all the time, to a pipe or the ground. Engineers combine observation and timing with targeted checks, such as flood tests of wet areas or isolating supply lines, to confirm the source before anything is broken out.
Repairing in the right order
- Stop the water at its entry point.
- Let the structure dry where possible.
- Repair the damage: corroded reinforcement and spalled concrete, as in our guide to spalling, then plaster and finishes.
- Check the result over time, for example after the next rain or a repeated flood test.
Water ingress control is part of Nation’s maintenance and rehabilitation service, together with the repair of the damage water has caused.
Questions
Why does a leak come back after painting?
Paint covers the symptom. If water still enters, it keeps wetting the wall and the paint fails again.
Can water damage the structure?
Yes. Persistent moisture is one of the main drivers of reinforcement corrosion and spalling concrete.