Efflorescence for Inspectors
by Nick Gromicko, Rob London and Kenton
Efflorescence is an accumulation of minerals and salts on
masonry surfaces, such as brick, cement, and sometimes stone.
Inspectors should know how to prevent against and remove this
unsightly residue. They must also be aware that, while
efflorescence itself is not dangerous, it indicates the presence
of excess water, which can lead to more serious structural and
How Efflorescence Forms
The earth contains natural salts that are present in the raw
materials that make up masonry products, such as concrete,
asphalt and stucco. These salts remain trapped within masonry in
solid form until they are dissolved into water, which usually
makes its way into the material through small pores. Water can
originate from rain, sprinklers, household leaks, or any number
of other places. Cold, dry air will draw this liquid back out of
the material where it evaporates, depositing the salt as a white
crystalline growth on the surface. Efflorescence typically forms
during cold, dry weather shortly after it has rained and moisture
has entered the masonry. It can occur year-round, but it is most
likely to form during the winter due to low temperatures.
As with mold, the appearance of efflorescence varies
greatly. It can be powdery, it can have sharp edges and be
easy to spot, or it can have indistinct edges. It can cover
a large area as a fine dust, or form large individual crystals.
Its appearance depends partly on the type of salt from which it
is composed, but humidity also plays a role in this
determination. In exceptionally dry climates, water can evaporate
before it even reaches the surface, in which case the salt will
accumulate unseen beneath the surface. In humid conditions,
moisture may take a long time to evaporate, allowing the slow
growth of “whispers” projecting from the
InterNACHI inspectors should already know how to distinguish
mold (pictured at right) from efflorescence, but it is possible
for homeowners to confuse the two. The expense of a mold test can
be avoided if the substance in question can be identified as
efflorescence. Here are a few tips that inspectors can offer
their clients so that they understand the differences:
- Pinched between the fingers, efflorescence will turn into a
powder, while mold will not.
- Efflorescence forms on inorganic building materials, while
mold forms on organic substances. However, it is possible for
mold to consume dirt on brick or cement.
- Efflorescence will dissolve in water, while mold will
- Efflorescence is almost always white, yellow or brown, while
mold can be any color imaginable. If the substance in question is
purple, pink or black, it is not efflorescence.
Aside from mold, the following conditions can result from
excess moisture in a residence:
- fungi that rot wood;
- water damage to sheetrock;
- reduced effectiveness of insulation.
Inspectors should note the presence of efflorescence in their
inspection reports because it generally occurs where there
is excess moisture, a condition that also encourages the growth
of mold. An exception can be made during the first few years of a
building’s construction when efflorescence will appear as a
result of moisture locked within the masonry in a process called
“new building bloom.” This moisture comes from water
added during the manufacturing or mixing process that will
undoubtedly contribute to efflorescence. This type of
efflorescence will appear all over the masonry material and will
continue to accumulate until the initial water supply is
exhausted, which can take up to a year. Efflorescence that
appears locally and after the “new building bloom” is
over is a symptom of excess moisture that can be problematic. The
source of this moisture should be determined and
Prevention and Removal of Efflorescence
- An impregnating hydrophobic sealant can be applied to a
surface to prevent the intrusion of water. It will also prevent
water from traveling to the surface from within. In cold
climates, this sealant can cause material to break during
- During home construction, bricks left out overnight should be
kept on pallets and be covered. Moisture from damp soil and rain
can be absorbed into the brick.
- Pressurized water can sometimes be used to remove or dissolve
- An acid, such as diluted muriatic acid, can be used to
dissolve efflorescence. Water should be applied first so that the
acid does not discolor the brick itself. Following application,
baking soda can be used to neutralize the acid and prevent any
additional damage to the masonry. Muriatic acid is toxic, and
contact with skin or eyes should be avoided.
- A strong brush can be used.
Note: The use of water to remove efflorescence may
result in the re-absorption of crystals into the host material,
from which they may later reappear as more efflorescence. It is
advisable that if water is used in the removal process that it is
dried off very quickly.
In summary, efflorescence is a harmless yet unsightly
accumulation of salts on masonry surfaces. Its presence indicates
excess water, a condition that can damage interiors and encourage
the growth of mold. Inspectors should know how to remove
efflorescence from surfaces, and educate their clients about its
identification and significance.