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EXTERIORS of buildings
ADHESIVES, EXTERIOR CONSTRUCTION
AGE of a BUILDING - how to determine
ALGAE, FUNGUS, LICHENS, MOSS
ANIMAL ENTRY POINTS in buildings
ANIMAL ODORS IN buildings
ARCHITECTURE & BUILDING COMPONENT ID
ART CONSERVATION - Cultural Heritage and Aerobiology
ARTWORK MOLD CONTAMINATION
ASBESTOS IDENTIFICATION IN buildings
ASBESTOS ROOFING / SIDING POWER WASHING
ASBESTOS ROOFING / SIDING DUST
ATTIC CONDENSATION CAUSE & CURE
BARK SIDE UP on DECKS & STEPS
BASEMENT WALKOUTS & COVERS
BEST CONSTRUCTION PRACTICES GUIDE
BRICK VENEER WALL Loose, Bulged
BRICK WALL DRAINAGE WEEP HOLES
BOOKSTORE - EXTERIORS
BUILDING SAFETY HAZARDS GUIDE
CAULK GUN TYPES, CHOICES
CAULKS & SEALANTS, EXTERIOR
CHIMNEY INSPECTION DIAGNOSIS REPAIR
COLUMNS & POSTS, DEFECTS
CONNECTORS, FASTENERS, TIES
DECK & PORCH CONSTRUCTION
DECK CONSTRUCTION BEST PRACTICES
DECK COLLAPSE Case Study
DECK FINISHES COATINGS PRESERVATIVES
DECK FLASHING LEAKS, ROT Case Study
DEFINITIONS of ENGINEERED WOOD OSB LVL etc
DRYWELLS, FRENCH DRAINS for FLAT SITES
EARTHQUAKE DAMAGED FOUNDATIONS
EIFS & STUCCO EXTERIORS
EXTERIOR WALL SIDING TRIM & FINISHES
EXTRACTIVE BLEEDING STAINS
FLASHING MEMBRANES PEEL & STICK
FLASHING for METAL ROOFS
FLASHING ROOF WALL DETAILS
FLASHING ROOF-WALL SNAFU
FLASHING SIDING DETAILS
FLASHING WALL DETAILS
FLASHING WINDOW DETAILS
FLASHING WOOD ROOF DETAILS
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FROST HEAVES, FOUNDATION, SLAB
FOOTING & FOUNDATION DRAINS
GALVANIC SCALE & METAL CORROSION
GLUES ADHESIVES, EXTERIOR CONSTRUCTION
GRADING, DRAINAGE & SITE WORK
GUTTERS & DOWNSPOUTS
HEAT TAPES & CABLES on Roofs for Ice Dams
HOUSE PARTS, DEFINITIONS
HOUSEWRAP / SHEATHING WRAP
HOUSEWRAP INSTALLATION DETAILS
HOUSEWRAP PRODUCT CHOICES
HOUSEWRAP at SILLS, SOLES, TOP PLATES
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INSECT INFESTATION / DAMAGE
KIT HOMES, Aladdin, Sears, Wards, Others
LEAD POISONING HAZARDS GUIDE
LEAD TEST KIT for HOME USE
LEED GREEN BUILDING CERTIFICATION
LOG HOME GUIDE
METAL LATH, PLASTER & STUCCO
MOISTURE CONTROL in BUILDINGS
MOLD DETECTION & INSPECTION GUIDE
MVOCs & MOLDY MUSTY ODORS
ODORS & SMELLS DIAGNOSIS & CURE
PAINT & STAIN GUIDE, EXTERIOR
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PAINT FAILURE DICTIONARY
PAINT LAB SAMPLE PREPARATION
PAINT SURFACE PREPARATION
PORCHES & Sunrooms
PORCH CONSTRUCTION & SCREENING
RAILINGS, DECK & PORCH
RETAINING WALL DESIGNS, TYPES, DAMAGE
RETAINING WALL GUARD RAILINGS
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF DORMER TYPES - PHOTO GUIDE
ROOF VENTILATION SPECIFICATIONS
ROT RESISTANT LUMBER
ROT, TIMBER FRAME
ROT, TIMBER ASSESSMENT
SEARS KIT HOUSES
SHEATHING, Gypsum board
Sheathing Celotex Homasote & Other
SHEATHING, FOIL FACED - VENTS
SIDING TYPES, INSTALLATION, DEFECTS
SINKHOLES, WARNING SIGNS
SOUND CONTROL in buildings
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
STAINS & Thermal Tracking
STAIN DIAGNOSIS on ROOFS
STAIN DIAGNOSIS on STONE
STAIRS, RAILINGS, LANDINGS, RAMPS
STONE CLEANING METHODS
STONE VENEER WALLS
STRAW BALE CONSTRUCTION
STUCCO WAll FAILURES DUE TO WEATHER
STUCCO WALL METHODS & INSTALLATION
STUCCO OVER FOAM INSULATION
STUCCO PAINT FAILURES
SURFACE GRADING, SITE DRAINAGE
TEST KITS for DUST, MOLD, PARTICLE TESTS
Thermal Expansion Cracking of Brick
THERMAL EXPANSION of MATERIALS
THERMAL IMAGING, THERMOGRAPHY
THERMAL IMAGING MOLD SCANS
THERMAL MASS in BUILDINGS
TREES & SHRUBS, TRIM OFF BUILDING
TRIM, EXTERIOR CHOICES, INSTALLATION
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
VINYL CHLORIDE HEALTH INFO
VINYL Siding or PLASTIC Window ODORS
Volatile Organic Compounds VOCs
WALL CONSTRUCTION BARRIER vs CAVITY
WATER BARRIERS, EXTERIOR BUILDING
WATER ENTRY in buildings
WIND ENERGY SYSTEMS
WIND TURBINES & LIGHTNING
WINTERIZE A BUILDING
How to diagnose, remove & prevent stains due to algae, fungal growth, or moss on stones, monuments, & on surfaces of building exteriors or roofs: this article describes and provide photographs and advice on identifying, cleaning, and preventing algae, moss, lichens, or fungal growth that occurs on stone surfaces such as buildings, gravestones, sidewalks, stone walls, and in nature. We include links to references useful in the identification of algae, moss, lichens, and mold. Our page top photograph shows a lichens and possibly moss coated tombstone in Australia provided by reader Patrick Walsh who consulted regarding cleaning and restoration of this family grave marker.
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We discuss the cleaning/restoration of the stone grave marker shown at page top in more detail at STONE CLEANING METHODS.
This website tells readers how to identify, evaluate, remove or prevent stains on building surfaces. Readers should see STAIN DIAGNOSIS on BUILDING EXTERIORS and STAIN DIAGNOSIS on BUILDING INTERIORS. For roof shingle stains, see STAIN DIAGNOSIS on ROOFS. Also see STAIN DIAGNOSIS on STONE and ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES where we describe not only moss and lichens but black fungal stains on asphalt shingles and on other building surfaces.
Our photo (above left) shows black staining on the stone surface of a mausoleum in Buenos Aires. Without closer examination we could not be sure if this was dirt and debris from city and traffic air, a dark fungus, or algae.
Our second photo of black growth on a stone roof (above right) was taken in Molde, Norway. Also see SLATE ROOF INSPECTION & REPAIR.
Algae and sometimes mold often appear on organic and even inorganic surfaces of buildings and in nature such as on asphalt roof shingles shown at ALGAE STAINS ON ASPHALT ROOF SHINGLES. It is possible that on these metal roof shingles (Justin Morrill Smith historic home in Strafford VT) mold or algae is hosted by a painted coating on the roof.
Watch out: on walks and decks algae makes for a dangerously slippery surface when it is wet.
More photos of algae, lichens, and moss, including both on building or stone surfaces and under the microscope are at ALGAE, FUNGUS, LICHENS, MOSS.
Green stains due to moss: unlike the algae staining above, thick green growth on a stone or masonry surface is more likely to be moss such as the mossy concrete entry platform at the New York home shown at below left. The moss on this surface holds water, is a slip, trip, or fall safety hazard, and depending on the hardness of the concrete, it may also lead to spalling or frost damage to the concrete itself.
Reindeer moss: Our second moss and lichens photo (above right, Quetico boundary canoe area, Canada) demonstrates that moss and lichens can coexist happily on the same surface, and even intermixed on a surface where we show two kinds of moss. In our photo, the taller pale growth among the green moss is itself "Reindeer Moss, Caribou Moss" or in other references "Antler Moss".
Our photograph shows Cladonia rangeferina or perhaps Cladonia sp. along with both moss and other lichens on the same stone. Reindeer moss is itself actually a lichen, and is an important food source for reindeer and caribou). Reindeer moss is quite fragile and slow growing, found in both hot and cold climates and in alpine tundra - don't trample it in the wild.
See Lichens on Stone Surfaces for our complete article on this topic. Excerpts follow. Also see Lichens on Roofs for a discussion of lichen damage to shingles and how to prevent lichens growth on roofs.
Lichens on Roofs demonstrate the mechanical damage that can be caused by lichens on surfaces. See Lichens on Roofs for details about the causes, effects, and prevention of lichens growth on roofing surfaces. Lichens is often found growing on roof shingles, especially asphalt and wood shingles as we show here where we demonstrate the damage to the surface when lichens is removed. Our photos (below) illustrate how serious lichens damage can be to a mineral surface.
Does Lichens Always Need to be Cleaned Off of Stone Surfaces?
Red stains on stone or masonry surfaces may be due to lichens, or on occasion bleed-down from rusting iron as we demonstrate just below.
Red stains on the surface of and as much as 1.5mm into Carrara and Condoglia Marble used in Italian monuments (the Certosa of Pavia facade, the Orvieto cathedral, the fountain statues of Villa Litta near Milan) have been reported by E. Zanardini et. als in Art, Biology, and Conservation: Biodeterioration in Works of Art, Robert J. Koestler et als. Eds., Metropolitan Museum of Art, 2003, ISBN 1-58839-107-8.
Apparently there is an association between a lead source, lead found in and on these works and lead-resistant microorganisms. The authors investigated this phenomenon and concluded that although red-pigmented microorganisms were present in the stains, "... their presence does not appear to be related either to the red coloration or to the presence of lead;" The conclusion was that the red stains on the Italian marble studied were due to the presence of lead.
Brown stains on stone, concrete, or brick are often caused by bleed-out from rusting components. In our rust-on-stone photo (below left) the deep brown stains in the bottom center of this photo (79th St. Boat Basin, New York City) are probably caused by the combination of salt from the roadway above, water leaks into and through the structure, and steel reinforcing rod or wire.
Our photo of the concrete tower in Buenos Aires (below right) shows rust stains on concrete at the catwalk brackets (click to enlarge).
Please see Catalog of Substances that Alter Stone, Glass, Steel where we provide an extensive table of biodeterioration agents that damage stone, glass or steel, excerpted from Cultural Heritage and Aerobiology, Methods and Measurement Techniques for Biodeterioration Monitoring, Paolo Mandrioli et als., expanded with three additional table lines for Actinobacteria and Gram-Bacteria listed in Art, Biology, and Conservation: Biodeterioration in Works of Art, Robert J. Koestler et als. Eds., Metropolitan Museum of Art, 2003, ISBN 1-58839-107-8, and finally, with minor additional editing and commentary by Daniel Friedman.
For conservators, the latter text, (Art, Biology ...) includes important studies on treatment and prevention of artifact deterioration, including studies of the use of biocides, anoxic eradication of fungi, and the use of other biocides or preparations for use in defense of cultural artifacts against microbial and environmental agents.
Methods for Cleaning & Preventing Future Organic Growth (Algae, Fungus, Lichens, Moss) from Stone, Brick, or Concrete Surfaces
Please see our complete article on this topic at Methods for Cleaning Stone Surfaces. Excerpts follow. Especially if you are restoring artifacts, art works, tombstones, or graves, avoid any aggressive cleaning methods that might damage the roof surface.
Mechanical Cleaning of Brick, Stone or Concrete Surfaces
The gravestone that was shown at the top of this page and appears below in "before and after" photos was successfully cleaned using simply a soft bristle brush and plain water. Here is what Patrick Walsh said about the cleaning procedure:
Whatever cleaning is done on a stone or masonry surface, make sure the process does not cause more harm than good to the artifact and to the environment around it.
Frequently Asked Questions (FAQs) about Algae, Fungus, Lichens, Mold, or Moss Growth on Exterior Surfaces
Question: How to clean off & prevent moss or green algae/fungal growth in a car wash
Hi, I own a car wash. I've been having a moss/algae problem that's becoming progressively worse. The problem is in the car wash tunnel. It began growing on the cloth used to clean the cars and now has spread to some of the steel components and the concrete floor as well. The Area is very damp, abundant in sunlight, and poorly ventilated overnight when the garage doors are closed.
Originally I had thought my water might be contaminated but I was told that because I have many windows in my tunnel that the sunlight is causing this, while another professional told me it was more likely due to poor ventilation.
I've been in the business for a long time and have had other locations, but never had a problem like this. I'm wondering if you might have any thoughts on what's causing this aside from the dampness factor which I can't help. Any input would be greatly appreciated. I've attached some photos. thank you, E.L. 6/12/2012
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with moss, algae, or fungal growth on building surfaces and materials, though I expect you are far more an expert on car wash operation and maintenance than most outside "consultants" you might find. That said, here are some things to consider:
Some of your photos indeed look to me like moss - I agree, especially along the steel guide track.
But others, on the cloths, may be algae or even a fungus. I couldn't tell for sure from your photo. We could have you take samples and send them to me for analysis to ID for sure what you've got, but because I suspect that the causes and remedies are going to be the same, I'm not sure that step is worth the trouble.
I'll do what I can to assist, pro-bono as long as we can keep the time and writing from becoming too consuming - what we learn will be useful to both of us.
Diagnosis of moss or algae growth in a car wash
Moss, algae, and fungal spores are airborne and are, in a practical sense, everywhere, all the time. So when one or more of these becomes a problem in a car wash it is helpful to ask why here, now and not in other car wash operations? The answer to cause is important in deciding on the cure. Otherwise, you could go to the expense and trouble of a clean-up only to have the problem occur all over again.
Let me pose some questions and perhaps when you see my line of thinking you, knowing the operation well, will think of similar questions to ask or discuss.
Are there significant differences at this car wash from other units you know about in regards to:
1. water chemistry or water recycling and treatment before re-use
2. ventilation design and operation. Are your vent fans working, ducts unobstructed, that is, not simply that they run, but do they work?
3. sun exposure, including near by shade trees, forest, wet areas around your property. It would be lack of sunlight, not presence of sunlight, that would encourage the growth of these substances in the car wash.
4. the age, duty cycle, fabric used, manufacturer or source or even batch number of the cleaning cloths that show a green growth (algae or moss or fungus or even a combination of all of these?)
5. the cleanliness, temperature, chemistry of rinse water
6. car wash facility cleaning & maintenance schedule or procedures
7. How long has the green growth problem been evident? To my eye, moss like shown in two of your photos does not appear over night or even in a month.
Cleanup & prevention of moss & algae in a car wash facility
I'm not satisfied to just clean the problem surfaces without having a guess at the underlying cause, but nevertheless we can discuss some beginning options.
Steel surfaces with thick mossy growth may need to be hand-scraped as a starting cleanup step.
Use a power washer (with a deck cleaner solution or you may have your own detergent solution) to clean the contaminated surfaces. If you want to salvage and continue using the suspended cleaning cloths, that's a synthetic fabric that should tolerate being removed from the spinner drum, placed on a flat concrete surface, and spray-washed with the power sprayer.
That cleaning won't remove 100% of the moss or algae but it should remove most of it and leave the materials looking clean.
I am doubtful that using bleach or other sanitizers is necessary and also doubtful that it would be long term effective on cloths and on unpainted steel surfaces. If there are painted surfaces nearby that also suffer these growths you might want to use a fungicidal sealant paint the next time those areas are cleaned, dried thoroughly, and then re-painted.
There are also algaecide products intended to be added to pools to prevent algae growth (Utikem and other ammonium chloride based products) but again I'm not sure
Questions & answers on the cause, cure, & prevention of algae, fungus, moss or lichens stains & growth on exterior surfaces such as stone monuments, buildings, roofs, & other site features. .
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.