Guide to diagnosing, removing, preventing stains on building exteriors or interiors:

This article describes the types of stains found on building surfaces and on cultural artifacts. We provide photographs and advice on identifying, cleaning, and preventing algae, moss, lichens, or fungal growth that occurs on roofs, walls, siding, trim, interiors, and 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.

The Guide to Types of Stains on Building Surfaces:

This website tells readers how to identify, evaluate, remove or prevent stains on building surfaces.

In the following guide to building and cultural artifact stains and growths on surfaces, we list types of stains by stain color & appearance, by building location or material, and by stain cause.

We distinguish among the following stuff that may stain or be found growing building roofs, walls, or other surfaces, with extra focus on asphalt shingle roofs as well as other roofing materials such as wood shingles, wood shakes, roll roofing, and even slate or tile roofs.

Some of these types of roof, wall, siding, stone, or interior stains or discoloration are only cosmetic in nature, while others may indicate growths that are likely to reduce the roof covering life. A more detailed, illustrated version of the exterior building stain list below is

at STAIN DIAGNOSIS on BUILDING EXTERIORS.

• Algae-caused black or green stains on roof or other building surfaces - Some photos of black algae stains are at Black ALGAE STAINS On Asphalt Shingles.
  For details on roof algae
  
  see ALGAE STAINS on ROOFS,
  
  and ALGAE STAIN TEST METHODS.
  
  Algae can produce black stains on asphalt roofing products. Also
  
  see ALGAE, FUNGUS, LICHENS, MOSS COMPARED.
  And
  
  " see STAIN DIAGNOSIS on STONE for examples of algae staining on other building surfaces.
• Black stains on asphalt roofing products such as asphalt shingles or roll roofing, caused by extractive bleeding (product defects) -
  
  see EXTRACTIVE BLEEDING on SHINGLES
  and
  
  see ROOFING MATERIAL DEFECT / environmentally-caused roof shingle stains.
• Black, brown, or gray stains on roofing products due to debris left on the roof surface, such as piles of leaves and organic waste from nearby trees.
  
  See DEBRIS STAINING
  and
  
  see ROOF SHINGLE STAINS, PROXIMATE CAUSE
• Black or other colored stains on roof surfaces may be caused by soot from chimneys, both wood-fired and oil-fired devices. Black or other colored stains may also appear on roof surfaces from nearby industrial activities.
  
  See SOOT STAINING
• Black stains on building interiors: such as on carpets, drywall, or trim:
  
  see STAIN DIAGNOSIS on BUILDING INTERIORS
  and
  
  then STAIN DIAGNOSIS on BUILDING INTERIORS
  and also
  
  see STAINS on INDOOR SURFACES, PHOTO GUIDE
• Brown or red stains on roof surfaces are often caused by rust from wearing steel flashing or other on-roof metal products.
  
  See RUST STAINS ON ROOFS
• CATALOG of BIOLOGICAL SUBSTANCES THAT ALTER STONE or Other Inorganic Materials lists the causes and types of damage that raise aesthetic and conservation issues on cultural artifacts, buildings, and art works.
• Chimney stains on roofs -
  
  see SOOT STAINING - Black Soot Stains on Roof Shingles Around Chimneys
• Debris stains on roof shingles -
  
  see DEBRIS STAINING - Black Debris Stains on Asphalt Shingle Roofs
• Extractive bleeding stains on asphalt roofs -
  
  see EXTRACTIVE BLEEDING on SHINGLES and
  
  see ROOFING MATERIAL DEFECTSt
  and
  
  see ROOF SHINGLE STAINS, PROXIMATE CAUSE (types of roof stain by color, location, probable cause).
  
  Extractive bleeding on wood siding -
  
  see STAIN DIAGNOSIS on BUILDING EXTERIORS for a discussion of siding stains traced to extractive bleeding for clapboards, wood shingles, or other products.
  
  Also
  see PAINT & STAIN GUIDE, EXTERIOR for a discussion of how to prevent the problem of extractive bleeding on siding.
  
  Extractive bleeding from hardboard and similar wood-product boards can be a cosmetic problem in or on buildings or in art works if it is not properly prepared and sealed before painting, as we investigated for an art conservator -
  
  see ARTWORK MOLD CONTAMINATION for details.
• Graffiti on building surfaces
  
  See GRAFFITI REMOVAL FROM BRICK CONCRETE STONE SURFACES
• Green roof stains on roof shingles, clay tiles, cement tiles, and asbestos cement roof shingles or newer fiber cement roof shingles are often caused by algae. For details
  
  see ALGAE STAINS ON ASPHALT ROOF SHINGLES.
  
  Moss on roofs is also often green and should be unmistakable in appearance.
  
  See ALGAE, FUNGUS, LICHENS, MOSS on ROOFS.
• Lichens growing on building surfaces - Lichens are not the same growths as moss or algae, and are difficult to remove without damaging the roof surface
  
  See LICHENS on STONE SURFACES, and
  
  also see LICHENS on ROOFS for details about how lichens can cause roof damage.
  
  See STONE, STUCCO & BRICK CLEANING METHODS
  
  and ALGAE, FUNGUS, LICHENS, MOSS on ROOFS for a guide to preventing lichen growth and stains.
  
  Also see ALGAE, FUNGUS, LICHENS, MOSS COMPARED for an explanation of the difference among these.
• Mold or fungus growing on roof surfaces or on other building surfaces -
  
  see ALGAE STAINS ON ASPHALT ROOF SHINGLES.
  
  See MOLD in BUILDINGS for a guide to looking for mold contamination in or on buildings,
  and
  
  see WHAT MOLD LOOKS LIKE for a guide to just what mold looks like on building surfaces.
  
  Be sure also to
  see STUFF THAT IS MISTAKEN FOR MOLD to avoid becoming excited about harmless substances that people think are toxic mold.
  
  If you know your building has a mold problem,
  
  see ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD.
• Moss on roofs and other building surfaces:
  
  see ALGAE, FUNGUS, LICHENS, MOSS on ROOFS,
  and
  
  see GREEN STAINS ON STONE. Green or other colored mosses are a bit easier to remove than lichens on roofing surfaces, but both can carry away mineral granules and damage the roof surface. Moss tends to hold more water and moisture on the roof surface. So in our opinion moss is more likely to damage a roof surface than lichens or algae. Also
  
  see ALGAE, FUNGUS, LICHENS, MOSS COMPARED.
• Rust Stains on buildings -
  
  see RUST STAINS on ROOFS - Red or Brown Rust Stains (on shingles)
• Soot or Creosote black or brown stains on roof surfaces near or below chimneys -
  
  see SOOT STAINING - Black Soot Stains on Roof Shingles Around Chimneys
  and
  
  see ROOF SHINGLE STAINS, PROXIMATE CAUSE
• Stains on stone or masonry surfaces -
  
  see STONE, STUCCO & BRICK CLEANING METHODS for cause, cure, and prevention
• Tree-caused stains on roofs -
  
  see ROOF SHINGLE STAINS, PROXIMATE CAUSE
• White stains on roof surfaces may be from wash-down of pigments in paint on surfaces above the roof such as a gable end or dormer wall; white or less-black roof surfaces may also be found below copper or aluminum flashing whose salts run down the roof surface in wet weather, preventing algae or moss growth and leaving a white area on an otherwise stained roof surface. Our article
  
  at ALGAE, FUNGUS, LICHENS, MOSS on ROOFS includes a photograph of this condition on a wood shingle roof.

 

Building Stain Cause, Prevention, Removal Research

• Also seeReferences or Citations at the end of this page
• Analysis of Modern Paints, Thomas J.S. Learner, Research in Conservation, 2004 ISBN 0-89236-779-2 [Chemistry of modern paints, overview of analytical methods, pyrolysis-gas chromatography signatures of basic modern paints and their constituents, Fourier transform infrared spectroscopy for paint analysis, direct temperature-resolved mass spectrometry, and analysis in practice - technical reference useful for forensic paint science, focused on art works -DF]
• 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
• Soiling and Cleaning of Building Facades (RILEM Report), L.G.W. Verhoef (Editor), Routledge; 1 edition (November 3, 1988), ISBN-10: 0412306700, USBN-13: 978-0412306709
  The report of a comprehensive investigation by RILEM which examines all aspects of the cleaning of facades, subject to soiling by both biological and non-biological agencies. The contributors are international authorities working in this field giving essential advice to all those who need to know how to approach the problems connected with the soiling and cleaning of building facades.
• Staining, Prevention of Premature Staining in New buildings, Phil Parnham, Taylor & Francis; 1996, ISBN-10: 0419171304, ISBN-13: 978-0419171300
  The appearance of ugly staining early in a buildings life, ruins an otherwise pleasing appearance, tarnishes the image of the owners and gives rise to costly refurbishment works. In this book Phil Parnham raises a number of questions that should be considered whenever a new building is being designed or built. These are: * why has staining become so prominent; * what causes premature staining; which parts of new buildings are likely to be affected; * how can it be avoided? By using a number of highly illustrated case studies, the author answers these questions and ends by suggesting measures that should be taken by all design and construction professionals to prevent premature staining.
• Paint Handbook: testing, selection, application, troubleshooting, surface preparation, etc., Guy E. Weismantel, Ed., McGraw Hill Book Company, 1981, ISBN-10: 0070690618, ISBN-13: 978-0070690615, [Excellent but a bit obsolete paint theory and practice, also a bit light on field investigation methods, out of print, available used-DF]
  How to select and apply the right paint or coating for any surface. The first major reference to help you choose the correct paint or other finish to do the job best on a particular surface exposed to a particular environment. Experts in the field give full advice on testing surface preparation, application, corrosion prevention, and troubleshooting. The handbook covers wood, metal, composites, and masonry, as well as marine applications and roof coatings. A ``must'' working tool for contractors, architects, engineers, specification writers, and paint dealers.
• O'Donnell, Dorothy C. THE CARE AND CLEANING OF FURNITURE AND FURNISHINGS (1984). Ohio State University Cooperative Extension Service 1985
  
  Excerpts are just below

Here is the basis of cleaning hard surfaces of furnishings.

Chemicals, either alone or in combination, are used to dissolve or break down the unwanted dirt, rust, grease, etc., without damaging the surface itself. These include bleaches, acids and solvents, the most widely used solvent being water!

Absorbent substances take up grease, moisture and liquids. Some of them are french chalk, talcum powder, fullers earth, soft cloths, blotters, and facial tissues. Abrasives are used to rub off or wear away the offending build-up. You move the abrasive on the surface by rubbing, shaking, etc.

Abrasives include whiting, pumice, rottenstone, cigar ash, and for some needs, small pebbles or gunshot.

Many times combinations of cleaning materials and ways of cleaning are needed. This is because soil, grease and corrosion are combinations of many reactions and substances.

Only the laboratory chemist should experiment with chemical reactions. The rest of us should understand that we are working with chemicals; that some of them can be dangerous; that we should follow directions as given.

The basis of care of a hard surface in furnishings is preserving the finish by protecting it, removal of surface dust, and, when needed, feeding and conditioning the material from which it is made. Care supplies and methods vary from dusting with a dry, soft, lintless cloth to the use of a cloth that is treated to pick up and hold dust, to washing with clear water; to feeding wood by rubbing with suitable oil. Care supplies are based on their compatibility with the material of the furnishing. Wood, marble, leather, brass and other metals -each requires its own care plan. Follow the advice given.

Commercially-made cleaners and polishes are on the market. You may prefer to purchase them instead of making your own. However, you will be a better consumer by knowing the types of ingredients that should be used for cleaning and polishing.

Unless you can ask a furniture store dealer, hardware or paint store dealer or a manufacturer an informed question, he cannot give you an informed answer. When the dealer or manufacturer understands what you want to know and why, almost always you will get accurate information as requested.

• Paint and Surface Coatings, Theory and Practice, R. Lambourne & T.A. Strivens, Ed., Woodhead Publishing Ltd., William Andrew Publishing, 1999 ISBN 1-85573-348 X & 1-884207-73-1 [This is perhaps the leading reference on modern paints and coatings, but is a difficult text to obtain, and is a bit short on field investigation methods - DF]
  Provides a comprehensive reference source for all those in the paint industry, paint manufacturers and raw materials suppliers, undergraduate and postgraduate students, and industrial paint users. R. Lambourne was in the Research Department at ICI Paints Division and the Industrial Colloid Advisory Group, Birstol University, UK.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: bleach damaged building siding by making it uneven in colour

(May 12, 2014) Robert Walters said:
my house is clear stained. it hasn't been recoated in quite awhile. i washed it with a bleach water solution but the clapboards are colored unevenly. is there anything i can do to have the surface be uniform in color before i clear coat it again.

Reply:

Robert,

I suspect that the bleach remained on some surface areas more than others, thus bleaching those areas to a lighter color. That may happen because of uneven wash absorption into the siding or because of inconsistencies in wash-down of the bleach solution.

At this point, telling you to apply a close-match stain to the whole wall may still not give good results, because if some old clear coat remains the new stain won't absorb evenly either.

I'd like to see some sharp photos of the situation (use the CONTACT US link at page top or bottom);

You may decide to test a pigmented stain to see if it will bond to the surface and even out the colors.

...

Continue reading at STAIN DIAGNOSIS on BUILDING EXTERIORS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ALGAE & MOLD STAINS on EXTERIORS
• ANIMAL STAINS & MARKS in BUILDINGS
• CHIMNEY STAINS & LEAKS
• CARPET STAIN DIAGNOSIS
• CONCRETE STAINS: ID & REMOVAL
• INSULATION STAINS - AIR BYPASS LEAKS
• PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
• STAIN DIAGNOSIS on BUILDING EXTERIORS
• STAIN DIAGNOSIS on BUILDING INTERIORS
  
• THERMAL TRACKING BRIDGING GHOSTING - home
• WALL STAIN DIAGNOSIS

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STAINS on & in BUILDINGS, CAUSES & CURES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING STAINS

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Citations & References

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