Efflorescence: deposit location versus water route
White mineral deposits mark where water evaporated; they do not identify the original source without the surrounding moisture pattern.
Diagram coordinates are explanatory, not measurements. Confirm the actual assembly before opening, testing or repairing it.
Dry masonry surface
The assembly remains dry enough that dissolved salts are not repeatedly transported to the surface.
Salt transport and evaporation
Water dissolves salts inside masonry, moves toward the drying surface and leaves crystals as it evaporates.
Watch the conditions
Deposit height, rainfall and whether the crystals return after cleaning reveal the active route.
Do not assume
White powder is not automatically mold, and cleaning it does not stop the water pathway.
Look for
- Low horizontal band
- Defined crack line
- Deposit below a concentrated exterior discharge
Keep competing explanations alive.
Map deposit height, weather exposure, first damp edge and drying direction. Photograph before cleaning so the exit pattern is preserved.
Ground or foundation moisture moving by capillarity
Moisture rises through porous masonry and leaves salts where evaporation occurs.
- Lower-wall concentration
- Persistent ground moisture
- Broad horizontal band
- Deposit starts below a local pipe or penetration
Rain entry through exterior masonry or joints
Wind-driven rain enters higher on the wall and exits at an interior evaporation zone.
- Weather and wind dependence
- Higher or localized pattern
- Exterior joint defects
- No rain relationship and strong lower-wall band
Local service water source
A pipe or condensate route feeds one masonry area and produces a concentrated salt deposit.
- Localized pattern near services
- Dry-weather recurrence
- Water-use or equipment relationship
- Broad seasonal ground pattern
Change one condition at a time.
Each answer changes the investigation order. It does not prove a hidden condition by itself.
Is the deposit a broad lower-wall band or a concentrated higher patch?
If yes: A lower band supports ground moisture; a high patch supports local or rain entry.
If no: Map the first damp edge during an active event.
Does the pattern change after rain or during dry-weather service use?
If yes: Use the trigger to separate exterior and interior sources.
If no: Continue long-term moisture mapping before repair.
