Why we investigate before repairing
Water can enter at one point and track along framing, through cavities and across floors before it shows indoors. Sealing the place where the damp patch appears usually misses the source, and sealing drainage paths by mistake can make the leak worse. The investigation compares what is seen inside with the construction outside so the repair goes on the right detail.
The six stages
Understand the history
Where the water shows, when it started, how it relates to the weather, and what has been tried. We review drawings, O&M manuals and previous reports where they exist.
Plan the access
The test zone outside and the observer inside have to be coordinated. Rope access, cradle, BMU, MEWP or the roof, set out in the RAMS.
Test defined zones
A controlled hose or spray bar at a set distance, pressure and duration, generally working from the bottom up, one zone at a time, following CWCT methods. An observer inside records exactly when and where water appears.
Trace the water path
Each internal observation is matched to the external test zone. Moisture meters and, where needed, opening up behind finishes help confirm the route. Joints, gaskets, drainage and interfaces are checked, not just sealant.
Carry out the agreed repair
Matched to the defect and the system: gaskets or seals, glazing re-beds, frame adjustment, flashings, cladding interfaces, masonry joints or membranes.
Re-test and report
After curing, the repaired zone is tested again by the same method. The report records the history, zones, results, repair and re-test, with photographs.
Details that are often involved
- Perimeter and movement joints
- Glazing gaskets, beads and pressure plates
- Cladding interfaces and cavity trays
- Drainage slots and weep holes, often blocked or sealed over
- Copings, flashings and membrane laps
- Balcony thresholds and soffits
What helps before the visit
- Photographs showing the affected area and its position on the building
- A history of the leak, the weather and previous repairs
- Previous reports and the O&M manual
- Plans and sections of the facade and waterproofing, if available
- Arrangements for the observer inside and safe access outside
Some investigations need access behind internal finishes to see the water path. We discuss this before the work is arranged. See the leak investigation service for how a job runs.
Common questions
Is this the same as a laboratory weather performance test?
No. This is a diagnostic site investigation. A formal performance test to a named standard has its own agreed method, equipment and acceptance criteria. If your project requires one, tell us before the visit.
Can there be more than one source?
Yes. Different defects can produce the same symptom. Finding and repairing one source does not prove every other part of the facade is watertight.
What if the leak does not appear during testing?
Weather dependent or intermittent leaks may not reproduce in a controlled test. Further monitoring, different conditions or a return visit may be needed. The report records what was observed rather than claiming an unobserved leak is resolved.