Q&A about how to clean & prevent building stains & algae, fungus, lichens & moss from exterior surfaces:

This article series describes cleaning, and preventing future algae, moss, lichens, or fungal growth that occurs on stone, brick, and other surfaces such as buildings, gravestones, sidewalks, stone walls, walks, roadways and in nature.

FAQs on Methods for Cleaning Organic Growth (Algae, Fungus, Lichens, Moss) from Stone, Brick, or Concrete

These questions & answers were posted originally at STAINS on STONE, STUCCO DIAGNOSE & CURE - be sure to see the advice given in that article.

On 2018-07-31 by (mod) - OK to use Simple Green Housecleaner - some caveats

Yes though not without some risks of

- uneven siding color results if the spraying and rinsing are not properly formulated and applied

- leaks into the building walls causing costly mold contamination, wet insulation, and perhaps risking insect attack too, if the spray is not properly done and water is blown into the wall structure.

- Damage to plants and grass around the building

There are siding cleaners specifically formulated for vinyl that may be preferred.

Above is a general purpose siding cleaner example from Simple Green.

In a second post I'll show the ingredients from the SDS for this product.

Ingredients in Simple Green Siding Cleaner -

[Click to enlarge any image]

Source: Home Depot: https://images.homedepot-static.com/catalog/pdfImages/1f/1f1725ec-5d48-4eef-93ac-25aae7c9ab98.pdf

Watch out: Yes you can use this cleaner to clean vinyl siding along with a pressure washer, though using any siding or exterior spray cleaner is not without some risks of

- uneven siding color results if the spraying and rinsing are not properly formulated and applied

- leaks into the building walls causing costly mold contamination, wet insulation, and perhaps risking insect attack too, if the spray is not properly done and water is blown into the wall structure.

On 2018-07-31 by Roberta Altman

Can this product be used with a pressure sprayer for vinyl siding on home?

On 2018-04-29 by (mod) - warning about protection gear when using any cleaner including original forms of TSP

Thank you for the warning and comment, Pam.

Our statement

Watch out: Be sure to wear rubber gloves when cleaning with this solution. [Note that trisodium phosphate is no longer used as a cleaning agent because it is an environmental contaminant.

intended to make clear that dangerous forms of TSP are no longer on the market.

The image you're seeing is a TSP substitute.

I suspect that the manufacturer kept the "TSP" in label because of its long-familiarity as an effective cleaner. notwithstanding that TSP stands for Tri Sodium Phosphate

and the box label states plainly that this "TSP" is "PHOSPHATE FREE" .

Still I'll find a way to edit to clarify the article as your concern is proper. THank you.

On 2018-04-29 by Pam

"Watch out: Be sure to wear rubber gloves when cleaning with this solution. [Note that trisodium phosphate is no longer used as a cleaning agent because it is an environmental contaminant.]"

am I missing something or should this statement (particularly the part in brackets) be posted in bold red letters next to the articles lead in and another photo of the TSP product box 1/2 way down the article? Not everyone will find this 'needle in a haystack' fine print warning in the article. Very possibly misleading. The article is good otherwise.

On 2017-05-02 by (mod) - scrubbing with vinegar - Bio/environmentally friendly, non chlorine based product to remove fungus

Try scrubbing with vinegar.

On 2017-05-02 by Larry

I'm searching for a Bio/environmentally friendly, non chlorine based product to remove fungus growth on external walls?

Can someone email me with ideas and product names, please...?

trucker69uk2001@yahoo.co.uk

On 2015-11-04 by (mod) -

Also see

Camps, J. P., and A. Laplanche. "Corrosion of concrete by sequestrating agents of detergents." In Protection of Concrete: Proceedings of the International Conference, University of Dundee, September 1990, p. 55. CRC Press, 2003.

I wouldn't try it.

On 2015-11-04 by (mod) - added TSP_PF to a wet concrete mix would it affect the concrete?

Ivan there's not much research on your question - at least not that I could find, but see

Khayat, Kamal Henri. "Effects of antiwashout admixtures on fresh concrete properties." ACI Materials Journal 92, no. 2 (1995).

Most antiwashout admixtures are water-soluble polymers that modify the rheological properties of fresh concrete. Such admixtures have been incor-porated into concrete intended for underwater placements and repairs, and implemented in production of extremely workable and flowing concrete.

They have also been used to enhance resistance to sagging of shotcrete and produce bleed-free cement grouts for filling post-tensioning ducts.

This paper presents results from a study aimed at better understanding of the effects of antiwashout admixtures on concrete properties.

It will highlight benefits and limitations of employing such admixtures in concrete.

Fresh properties of low-, medium-, and high-strength concretes made using two types of antiwashout admixtures, a microbial polysaccharide and cellulose derivative, were evaluated.

Fresh properties are compared with those of similar concretes made without antiwashout admixtures.

Among the parameters evaluated are fluidity, bleeding, water dilution, segregation, setting time, and air content.

Test results show that incorporation of an antiwashout admixture can greatly reduce external bleeding and significantly enhance resistance of concrete to water dilution and segregation.

However; there is a signijcant increase in water demand, and a high-range water-reducing admixture (HRWRA) is needed to maintain a desired level of fluidity without excess addition of water.

The combined additions of an antiwashout admixture and HRWRA delay setting time, especially at high concentrations of HRWRA. Viscous concretes containing antiwashout admixtures show a greater demand for air-entraining admixture. However; once enough air is entrained, proper air-void parameters needed to insure good freeze-thaw resistance can be obtained.

On 2015-11-04 by Ivan Freeman

If I added TSP_PF to a wet concrete mix would it affect the concrete and would it prevent the formation of black algae.

On 2015-05-25 by Nancy

oops.... typo

"It isn't safe FOR the kitty cats."

Moss is growning on some sections of the brick on my house, as well as some areas of my concrete sidewalk and drive way. (1960's Texas ranch style house) I have several stray cats that have adopted me and taken up residence in my backyard where the moss is growing on the brick and sidewalk under my arbor.

The bleach mixture works, but isn't safe if the kitty cats.

Does anyone have a suggestion on how to clean off the moss and prevent it's regrowth?

thank y'all
Nancy

On 2015-05-22 by (mod) - remove lichens from an iron sculpture located outdoors;

Wire brush, clean, re-paint with a paint containing an algecide. Increasing sun exposure.

Watch out: Always take care to start any cleaning project with the least-aggressive approach first to minimize the chances of causing damage.

On 2015-05-22 1 by WHWISNERMD@AOL.COM

HOW CAN I REMOVE LICHEN FROM AN OUTDOOR IRON SCULPTURE?

Question: how to clean awnings

(Sept 16, 2011) Marge said:

How can we clean cloth awnings of algae, lichens, fungi, muld. It is snall, yellowish, circular tufts, similar to daisy or aster centers. Thanks for your help.

Reply:

Typically we clean awnings using a combination of a soft scrub brush and a sprayer, or a power washer.

Stay away from bleach lest you discolour the awning fabric.

You may increase the resistance of the cloth awnings to further algae and mold growth by treating the dry fabric with a water repellant.

Question: so TSP is OK?

Judy Frisch said:

So are you saying the TSP PF mixture is OK for using on granite stones to clean off the mold and fungus?

Reply: orignal TSP is no longer sold nor used

Judy, yes TSP-PF, a TSP substitute, is used on some stone surfaces.

The orignal TSP is no longer used because it's an environmental contaminant. Depending on what the stone is and what sort of staining is discolouring it, you might want to review the advice

at MARBLE CLEANING METHODS

Question: clean up mold on used brick entry

(Oct 17, 2012) Shawn said:

What should I use to remove mold that has developed due to a leak and the mold has formed on my used brick wall in my entry way in my home.

Reply:

Shawn we give extensive mold cleaning procedures and advice

at MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD

Watch out: often on masonry people mistake leak or moisture related white mineral salts for mold.

See EFFLORESCENCE SALTS & WHITE DEPOSITS

Question: lichens problems on on concrete roof tiles, patio furniture, other surfaces

(Nov 13, 2012) Ewan said:

My concrete roof tiles were repainted 4 years ago and due to trees in the area the tiles have developed lichen on some surfaces. How can I remove the lichen without damaging the repainted surface?
Thanks.

(June 23, 2014) corker2012 said:

I have a heavy lichen buildup on outdoor patio furniture (not wood or metal). Some type of fabric. It's getting out of control and I don't want to replace.

Reply:

Ewan,

Chances are you cannot mechanically remove lichens growth without damaging the surface on which it is adhered. But use of metallic strips whose wash-down will over time kill off lichens or moss on a roof can be helpful.

See the advice at ALGAE, FUNGUS, LICHENS, MOSS on ROOFS.

Corker,

Lichens on fabrics is a bit unusual, are you sure it's not an algae? Try a non-sudsing detergent cleaner and scrub brush.

Metal salts and some fungicidal sprays will deter lichens growh, as you can see on many roofs where the area of wash-down below metal flashing is often lichens and moss free.

Bill,

the bleach method you describe may be perfect for patio furniture is not suitable for some building surfaces such as roofs or siding as it can can cause run-down stains and discoloration; also aggressive removal of lichens from some surfaces, particularly asphalt shingles or roll roofing, causes additional mechanical damage. Better solutions for lichens in particular are
at LICHENS on STONE SURFACES
and
at ALGAE, FUNGUS, LICHENS, MOSS on ROOFS

Question: algae in water tank

(July 16, 2014) Anonymous said:

algae and fungai in water tank suggest how to clean

Reply:

Anon,

You will need to drain and disinfect the water storage tank. See these two procedures that will help you out

WELL CHLORINATION SHOCKING PROCEDURE - shocking the well or sanitizing the well

and

WATER SOFTENER CLEANING & SANITIZING

- sanitizing a water softener - a similar problem to yours

Question: chemical cleaners for white marble

(Nov 21, 2014) Anonymous said:
hello
I am new here, can you please tell me how to clean a white marble?
and plese tell me which chemical is best for use...

Reply:

sure anon, see MARBLE CLEANING METHODS

Question: black stains on outside of block house wall

(Nov 30, 2014) Charlie Chisppe said:

Black stains have developed on the facade of my house which is made from breeze block
How can I clean?
Thanks

Reply:

Charlie

In the article STAINS on STONE, STUCCO DIAGNOSE & CURE see the section titled

Do-it-yourself Cleanup for Algae or Fungal Stains on Stone, Brick, Concrete Surfaces

...

Continue reading at STAINS on STONE, STUCCO DIAGNOSE & CURE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• STAIN DIAGNOSIS on BUILDING EXTERIORS - home
• STAINS on STONE, STUCCO DIAGNOSE & CURE
  • BIODETERIORATION CATALOG for STONE GLASS STEEL
  • GRAFFITI REMOVAL FROM BRICK CONCRETE STONE SURFACES
  • LICHENS on STONE SURFACES
  • MARBLE CLEANING METHODS
  • STONE, STUCCO & BRICK CLEANING METHODS

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