a white powder deposit efflorescence efflorescence indicating moisture in the wall
The white staining is called efflorescence indicating moisture in the wall.

Efflorescence is an eyesore! This is the presence of the white powder that forms on the face or surface of concrete, plasterwork and brickwork indicating moisture in the wall. Blooming or flowering are other names for efflorescence.

It is a cause for concern!

Efflorescence is a build-up of minerals and salts staining the surface of the concrete, brick and plasterwork due to repeated bouts of excess water in the material. The minerals and salts that naturally occur in the material are dissolved when the brickwork, plasterwork or concrete is waterlogged indicating moisture in the wall.

Concrete, pavers, brickwork and plasterwork are porous and can absorb or wick water and draw salts to it like a tree transports water from its roots to its leaves. This is capillary action. When efflorescence or blooming happens, it can indicate a moisture issue that could potentially damage the structure.

When water reaches a building material’s surface, evaporation will occur. Water absorption and wicking will continue after the water evaporates and the salt is left behind looking like flowering or blooming. This eventually creates a high salt concentration, leading to osmosis.

What is Osmosis

Simply put, osmosis in building materials is the movement of water from a region of low salt concentration to a region of high salt concentration in the material.

During osmosis, water moves toward salts and minerals to reduce its concentration. It can cause large hydrostatic pressures within the porous building material. As a result, these pressures can damage or destroy the material.

Osmosis can cause pressure that ranges up to 200 bar, exceeding the structural strength of concrete or brickwork. As a result, osmosis may result in porous building material staining, cracking, flaking or falling apart.

While the efflorescence or blooming is only a cosmetic problem in itself, its appearance on the wall indicates an ongoing water intrusion problem.

That means if you notice efflorescence on any concrete, plasterwork, brickwork or other structures, it’s important to take action by finding and eliminating the source of the moisture intrusion.

Most Common Causes of Efflorescence

Garden irrigation systems

One common cause of minor efflorescence is a sprinkler head that sprays on the walls of the building.

Frequently wetted areas:

Repeatedly washed and wetted concrete can form blooming or flowering, such as a garage floor, stoop or paving.

Leaks in walls

A leaking water pipe or waste pipe in the wall of the building may cause efflorescence both internally and externally.


Water may accumulate within a wall as a result of condensation. Things that take place inside such as cooking, bathing, washing and other actions employing water internally cause condensation. During cold weather, building interiors heated to normal comfort settings may contain enough moisture to cause condensation on cooler walls or on the underside of ceiling and roofing materials.

Contact with the ground

When brickwork, plasterwork and concrete are in contact with the earth, groundwater may be absorbed by the material. Moisture may rise through capillary action several feet above the ground. This may occur in the building’s plinth brickwork and columns if there is water ponding against the plinth. Efflorescence also often occurs on the bottom of retaining walls.

Lack of roof drainage

Lack of roof drainages such as gutters and downpipes will allow rainwater to pour off the roof to splash up against the walls. This can cause moisture intrusion into the walls and efflorescence on the walls. The bubbling of the painted and plastered wall finishes will result.

New buildings

A new building will sometimes have a minor efflorescence bloom. The moisture still in the material from the building process is evaporated away during the first months following construction.

Freestanding structures

a white powder deposit called efflorescence indicating moisture in the wall

Chimneys, freestanding walls and parapet walls on balconies and roofs are the most susceptible. They will most likely show signs of efflorescence in the top section of the wall.

Water Pooling

Water pooling on brick and concrete paving will cause efflorescence blooming.

Defective installations

Roof leaks and leaks around windows and doors may cause efflorescence and staining on the structure of the building.

Some of the best ways to remove efflorescence include:

Pressurised Water

A strong jet of water will dissolve efflorescence quickly. If you use water, dry off the water from the building material after application. If you fail to remove the water, the staining or salts may remain which can cause efflorescence to reappear.

Diluted Vinegar

You can use diluted white vinegar on efflorescence. It’s less harmful than industrial chemicals. You most likely already have vinegar in your kitchen.


With a strong brush, you can remove efflorescence with ease.

Removing efflorescence can be quick and simple. In fact, efflorescing salts are water-soluble, which means efflorescence may disappear on its own due to normal weathering.

What can I do about efflorescence?

The fact that water has penetrated the structure is the root issue. Furthermore, the moisture intrusion will likely be the cause of the eventual repair or replacement work that will be required.

Efflorescence is associated with potentially severe underlying complications. Therefore, it is highly advisable to seek expert advice to determine the source of the moisture intrusion causing the efflorescence.

If you have an efflorescence problem or suspect there may be a leak somewhere in your home, it’s wise to call me before you call a repair company. Repair companies have a vested interest in getting work. As a result, you have to be careful in accepting what they say requires repair or replacement.

I provide an unbiased opinion. I have no gain out of the evaluation of things that need repair (e.g., your roof or foundation).


Inspected Once, Inspected Right!®


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