Do these signs look familiar?
- It leaks only, or mainly, when it rains
- A stain on the top floor or beneath a terrace
- Bubbling paint on the facade
- An overflowing gutter or box gutter
- Water run marks in the loft
What could be causing the problem?
- Terrace waterproofing at the end of its life
- Loose flashing around a chimney or roof window
- A cracked facade joint
- A blocked gutter or box gutter
- A hairline crack in the render
Water does not always travel straight down.
It can enter through a waterproofing defect, travel along a beam or floor slab, then emerge several metres away. That is why we look beyond the area directly above the stain. The link with rainfall and exposed areas helps guide the investigation.
Connect the marks to areas exposed to water
We compare when the marks appear with rainfall and inspect accessible areas: flat roofs, facades, windows and rainwater drainage. Targeted water tests or dye tests can then help distinguish between possible paths, with an observation point arranged in advance.
In one damp cellar case, checks pointed towards rainwater drainage and the cast iron vertical pipe without confirming the exact point. This kind of finding calls for a further check, rather than replacing the entire roof based on a stain alone.
Identify the defect before defining the repair work
The report distinguishes the area tested, the water path observed and the entry point where established. It may also identify a likely source and further access needed. Resealing a joint, repairing a rainwater fitting and renewing waterproofing involve different work: the repair scope is defined after the diagnosis.
Your practical questions
Can you investigate water ingress in dry weather?
Depending on access and the surfaces involved, targeted water tests may be possible. They are carried out section by section to observe the water's path.
Does the leak necessarily come from the roof?
No. A terrace, facade joint, window or drain may be responsible. The position of the marks and their appearance after rain help guide the checks.
Do you also repair the waterproofing?
The next steps depend on the defect found. A local repair and a complete roof replacement require different trades and work. The repair scope is clarified after the diagnosis.
How much does a water ingress investigation cost?
Exposed areas, observation points and access from homes or shared areas determine which checks are possible. View the price guide ; the scope is defined before water testing starts.