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Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
MOLD: A COMPLETE GUIDE to TEST CLEAN PREVENT
ACTIVITY of MOLD in BUILDINGS
AGE of MOLD - Old is the Mold?
AIR CLEANER PURIFIER TYPES
AIR FILTERS for HVAC SYSTEMS
AIR TEST SAMPLING CASSETTE STUDY
AIRBORNE MOLD COUNT NUMBER GUIDE
AIRBORNE PARTICLE ANALYSIS METHODS
ALLERGEN TESTS for BUILDINGS
BROWN HAIRY BATHROOM MOLD
BIBLIOGAPHY for ENVIRONMENTAL HEALTH, MOLD, IAQ
BLACK MOLD, HARMLESS COSMETIC
BLACK MOLD, TOXIC & ALLERGENIC
BLEACHING MOLD, Advice about
BOOK MOLD, Moldy Book Cleaning
BOOKSTORE - ENVIRONMENTAL
CACTUS FUNGI / MOLD
CAR MOLD CONTAMINATION
CARPET DUST IDENTIFICATION
CARPET PADDING ASBESTOS, MOLD, ODORS
CARPET FUNGICIDAL SPRAY
CARPET STAIN DIAGNOSIS
CARPET & other STAIN TESTS
CARPET TEST PROCEDURE
CARPETING & INDOOR AIR QUALITY
CHAIN OF CUSTODY - TEST SAMPLE
CLEARANCE INSPECTIONS - MOLD CLEANUP
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
DIRT FLOOR MOLD CONTAMINATION
Disinfecting Buildings with Bleach
DO-IT-YOURSELF MOLD CLEANUP WARNINGS
DUST ANALYSIS for FIBERGLASS
DUST, HVAC CONTAMINATION STUDY
EFFLORESCENCE, Salts & White / Brown Deposits
FEAR of MOLD - MYCOPHOBIA
Fiberboard Insulation Sheathing Mold
FIBERGLASS INSULATION MOLD
FIND MOLD, ESSENTIAL STEPS
MOLD in BUILDINGS
FIRE DAMAGE vs MOLD DAMAGE
FLOODS IN BUILDINGS-mold
FOXING STAINS on books & papers
FUNGICIDAL SPRAY & SEALANT USE GUIDE
GAS DETECTION INSTRUMENTS
GAS EXPOSURE EFFECTS, TOXIC
GAS EXPOSURE LIMITS & STANDARDS
GAS TEST PROCEDURES
HOUSE DUST ANALYSIS
HOUSE DUST COMPONENTS
HUMIDITY CONTROL & TARGETS INDOORS
LAB PROCEDURES MICROSCOPE TECHNIQUES
LIGHT, GUIDE to FORENSIC USE
MEDIA BLASTING for MOLD REMOVAL
METHANE GAS SOURCES
MICROSCOPE DIGITAL PHOTOGRAPHY
MEDIA BLASTING for MOLD REMOVAL
METHANE GAS SOURCES
MICROSCOPE DIGITAL PHOTOGRAPHY
MILDEW ERRORS, IT's MOLD
MILDEW REMOVAL & PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD: A COMPLETE GUIDE TO MOLD
MOLD EXPERT, WHEN TO HIRE
MVOCs & MOLDY MUSTY ODORS
MYCOPHOBIA, STAINS MISTAKEN for MOLD
MYCOTOXIN EFFECTS of MOLD EXPOSURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
RENTERS GUIDE TO MOLD & IAQ
ROBIGUS & Wheat Rust Fungus
SMELL PATCH TEST to Track Down Odors
STAINS on & in BUILDINGS, CAUSES & CURES
THERMAL IMAGING MOLD SCANS
TRAPPED MOLD BETWEEN WOOD SURFACES
UV LIGHT BLACK LIGHT USES
VAPOR BARRIERS & CONDENSATION
VENTILATION in BUILDINGS
Volatile Organic Compounds VOCs
WATER ENTRY in buildings
Red or Brown Building Stains & Deposits that are not mold: Here we illustrate and explain the cause & cure of reddish brown or pale yellow bubbly surfaces on walls, especially masonry walls or on masonry chimneys, caused by leaks & moisture - efflorescence and sometimes creosote leaks.
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When investigating a building for a mold problem, you can save mold test costs by learning how to recognize Stuff that is Not Mold or is only Harmless Mold but may be mistaken for more serious contamination - save your money.
Our photo at page top shows white fluffy crystals of mineral efflorescence near the bottom of a poured concrete foundation wall.
White and other colors of effloresence deposits are shown at Efflorescence & white deposits. To clean off effloresence, see our advice at What steps should I do to remove efflorescence from my building?.
Because some clients have on occasion sent samples to our lab that really should not have been collected, much less looked-at, I provide this library of photographs of things that are "not mold" and don't need to be tested. These are substances that you can easily learn to recognize in buildings.
Save your mold test money, and increase the accuracy of your mold contamination inspection or test for toxic or allergenic mold in buildings: review these items to learn recognize non-fungal materials or even possibly harmless cosmetic "black mold" often mistaken for "toxic fungal growth."
These two photos of ugly reddish brown and white bubbly "growth" on a wall were sent to us by a reader. This stuff looks like terrible mold but it's probably not mold at all.
We won't know for sure without testing the material or inspecting the building.
But it sure looks like reddish-brown salts left behind by water and moisture passing through a masonry wall or a plaster wall, evaporating from the wall surface and leaving behind all of the crud that the moisture picked up from the wall itself as it passed through.
We often find this darker colored wall deposit on older buildings built of brick and stone whose interior wall surface is plaster applied directly to the masonry wall. We also often find this wall "growth" when water has been leaking in a plaster wall cavity.
Plaster is so alkaline that it is not as friendly to mold growth - it's not "mold proof" as mold may grow on or in paint or even on or in organic material in or on the plaster.
What is Causing the Bubbling and Peeling of Paint on Foundation Walls?
Take a look at this closeup (above left) of peeling paint on a foundation wall in a basement. The lumpiness of the surface tells us that this wall has been painted a number of times, painting over a rough concrete or concrete block surface.
In the center of the photograph (above left) you can see where paint is falling away and the gray concrete or concrete block is exposed. At the upper left corner especially you can see rounded bubbles of material that looks as if it is "growing" on this foundation wall.
The author's hand (photo above right) shows a combination of peeling paint, deteriorated masonry surface, and mineral salts all left behind as water and moisture have been passing through the building foundation. There is a water problem in this building and a moisture problem, but the stuff on the wall and in hand is not mold.
These pictures shows combination of peeling paint and yellowish-white mineral salts left behind as water is passing through this wall as moisture or as actual liquid water.
The moisture is both pushing paint off of the surface and also leaving behind salts of various minerals that were dissolved out of the wall as the moisture passed through it. When water evaporates from a surface it leaves behind minerals that were dissolved in it.
In our photo at above left we see bubbling paint and plaster on an interior wall surface - an indication of the "lift" power of the mineral crystalline salts formed as effloresence under a paint layer.
White powdery stuff appearing on a brick chimney may show up indoors or outside (photo above left). Brown stains leaking out of any chimney (photo above right), whether masonry or metal, may indicate a dangerous condition - prompt inspection is needed.
We find these stains on concrete block or "cinder block" chimneys as well, and occasionally on stone chimneys.
Brown stains on a chimney wall may also show up indoors or outside (photo above right). The brown stains are probably from creosote or soot washing out of the chimney interior flue and leaking into the attic through the chimney wall. This chimney needs immediate inspection and repair.
In either case we recommend that you promptly hire a professional chimney sweep to inspect the condition of the chimney including at the rooftop and inside the chimney flue. Water leaks into a masonry chimney can damage it and make it unsafe both structurally and with respect to leaking dangerous flue gases or even sparks that could cause a fire.
See CHIMNEY INSPECTION DIAGNOSIS REPAIR for details.
MOLD & HEALTH WARNING: although efflorescence is not mold, it often indicates wet conditions that cause problem mold growth elsewhere in the same building. You'll need to identify the sources of moisture or leaks and correct them, and depending on other building air quality complaints or health concerns it may be appropriate to inspect and screen the building for problem mold or other moisture or water-related problems.
Where you find efflorescence in a building indoors, you should look for problem mold, allergens, bacteria. Look on organic surfaces - wood, paper, painted surfaces, insulation, fabrics, carpets, carpet padding, or in settled dust and debris.
In our photograph (above left) the client is pointing out that water has been entering this basement from the very top of the foundation wall (due to outside roof spillage and bad drainage) - we did not agree with the contractor who told her this was "rising damp" due to wet soils.
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Frequently Asked Questions (FAQs)
Question: What steps should I take to remove efflorescence from my building?
What steps should I do to remove the efflorescence in my building? - Valerie Mercer
Reply: Ordinary Cleaning of surfaces followed by finding and fixing the moisture source are needed
Effloresence deposits on indoor surfaces
You can remove indoor mineral salt effloresence from a surface by ordinary cleaning methods. If the surface is dry enough not to harm the equipment, I'd start by vacuuming the surface to get rid of most of the loose material.
Dehumidification for effloresence control? You might think that indoors you could just run a dehumidifier but in my opinion that won't fix an effloresence problem since almost always effloresence on masonry surfaces indoors is caused by outside moisture that is penetrating the building.
Masonry sealer paints for effloresence control? Painting the interior side of an exposed masonry foundation wall with a masonry sealer paint will not fix an actual basement wall leak and in such cases the paint job will not be long lasting protection against effloresence either. However, painting the interior surface of the foundation wall with an appropriate sealer paint will slow down the passage of moisture through the wall and thus slow the formation of mineral salts in the future.
Incidentally, in our white effloresence photo (above left), the concrete wall had been painted, but not with a masonry sealer paint. We can make that guess because masonry sealer paints typically appear thicker and more granular on the wall due to their content of portland cement and sometimes sand for added body and waterproofing.
How does the sealer paint work to help against basement moisture? A significant factor in the movement of moisture (as opposed to an outright water leak) through a foundation wall is the combination of capillary action that moves water molecules through a substance and evaporation from the indoor wall surface that acts as a molecular pump to send that moisture into the building air. By sealing the inteior surface of the foundation wall we are significantly slowing the capillary movement of water thorough the wall by interfering with its ability to reach and evaporate into room air.
Effloresence deposits on outdoor surfaces
On an outdoor masonry surface you can use soap and water or just plain water and a spray hose or if the surface can tolerate it, a power washer to remove effloresence.
Watch out: take care not to blow water into the building nor damage exterior surfaces when using a power washer / sprayer. For example, many antique brick walls use bricks whose exterior skin is hard from the firing procedure. But if your power washer (or for painters, your sand blaster) removes that hard coating from the exterior brick, the exposed soft brick will weather, leak, and deteriorate rapidly. You'll have ruined the wall.
Find and fix the outside moisture source of leaks into a building interior or into a building exterior masonry component
Watch out: when the surface is dry and looks better or even perfect, you will nevertheless see a return of the efflorescence unless you find and fix the exterior leak source.
Outside, for example when you see efflorescence on portions of a brick chimney, I'd look at the chimney crown and roof flashings to be sure we're not allowing water to penetrate the chimney interior. After cleaning an exterior masonry surface we sometimes will treat the surface with a silicone or similar waterproofing compound such as products sold by Thompson's Water Seal™. (To remain effective, such coatings need to be renewed frequently.)
Details about tracking down and fixing sources of leaks into buildings and thus about preventing effloresence deposits (as well as mold and "mildew" in buildings) are found at STAIN DIAGNOSIS on BUILDING INTERIORS, and MOISTURE CONTROL in buildings as well as HUMIDITY LEVEL TARGET also VENTILATION in BUILDINGS and WATER ENTRY in buildings.
Question: effloresence on our walls - seems to be drying out, should I be concerned
Hi, will 9 years of no eaves troughs cause Efflorescence? When we bought our home it had no eaves and we installled them immediately. Now 6 years later there are white marks suddenly appearing 6 inches above the floor on the garage concrete. I am fairly positive this area has been drying out visibly, should we be concerned? - Laura 5/13/2012
Small amounts of effloresence that dry out and are not signs of pumping significant moisture into a building, if they are on a solid masonry wall, are more of a cosmetic than a functional worry.
But large areas, constantly growing mineral crystals, or stains that suggest that significant amounts of moisture are being pumped into a building can be signs of or contributions to related problems with indoor mold contamination. For example, effloresence on the plaster surface of a wood framed, insulated wall, means there is quite likely problematic moisture inside the wall, inviting mold, moldy insulation, wood rot, or insect damage. In such cases, further investigation of the cause, extent, and measures to cure the moisture source would be in order.
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