▽ +09.00Problem · Basements & below ground
Damp on the inside face of a buried wall
Persistent damp or stains on the inside face of a wall against soil or a tank, with no running water.
What you see
- Damp patches that never fully dry
- Paint blistering and peeling
- Efflorescence and crumbling plaster
- A musty smell and mould on finishes
Possible causes
No external waterproofing
Moisture moves through the concrete by capillary action and as vapour.
A damaged external membrane
Damage during backfilling, or a gap at the base.
Wet soil against the wall
Irrigation, poor drainage or a nearby tank.
Vapour-tight finishes inside
Moisture gets trapped behind paint or cladding.
How it is diagnosed
The diagnosis confirms the cause before any repair is chosen.
Moisture mapping
Readings at different heights and over time.
Check the outside
Irrigation, drainage, ground levels and tank positions.
Rule out condensation
Cold surfaces in humid air give similar signs.
Check the concrete
Before choosing a negative-side system.
- Crystalline coat
- Pores and capillaries
- Crystals formed
Possible solutions
The fix follows the diagnosis; these are the common options and their systems.
Crystalline treatment from inside
Works inside the concrete pores and cannot be pushed off.
Systems
A rigid cementitious system for negative pressure
On sound concrete, after the cracks are treated.
Systems
Injection where water enters
At cracks or joints.
Systems
External membrane and drainage where accessible
The most complete fix where excavation is possible.
What not to do
- Sealing the inside with vapour-tight paint
- Flexible membranes on the negative side: water pressure pushes them off
- Ignoring irrigation or drainage outside
General educational content; final values and requirements follow the manufacturer’s TDS and the approved project specification.
Common questions
What does “negative side” mean?
The face opposite the water source: the inside of a basement or the outside of a full tank. Systems applied there must resist water pushing them off the surface.
Will paint or plaster stop a damp basement wall?
No. Ordinary paint and plaster blister and peel under water pressure and moisture. What works is a system designed for the negative side — cementitious or crystalline — after the cracks and joints are injected.
Technical inspection
Need a diagnosis for your case?
Send photos, a description and the location; our engineers identify the cause and the fix after an inspection.