The removal of stains at times is a hit and miss proposition. Although the nature of stains is known, successful removal is not always possible. Application of an incorrect cleaning agent can set a stain, making it impossible to remove. It can also damage adjacent areas without having a favorable effect on the stain. Before applying a chemical cleaning agent to an entire stain, clean a small area in an inconspicuous spot to test it.

Stains described in this section are more easily removed with chemicals specifically formulated to remove various stains encountered on masonry walls, sidewalks, driveways, and other structures. These chemicals are available at chemical companies that specialize in cleaning chemicals. These companies may not be readily available, but all ship their products, and some may have representatives with limited inventory in your area.

Before applying any cleaning agent, it is important to know and remember how chemical cleaning agents remove stain. They dissolve, emulsify, or bleach the stain. Determine what the stain is and which is the best way to remove it.

One cleaning agent most often removes more than one particular stain, although experimentation may be necessary to determine the effect it has on various stains. Most stains can be removed, but there are some, which cannot be removed entirely.

The manufacturer’s instructions may not include the application procedures for removal of the particular stains in question. If not, test several types of chemical cleaning agents to determine which chemical successfully removes the stains.

The figure forty ($40) to fifty ($50) dollars base price applies to removal of stains in this section also, whether bidding by the hour or per job. It is very unlikely that the stains in this section, other than moss removal from a roof, would be of sufficient size to warrant bidding by the square foot. The price of any chemicals used during cleaning by the hour, is in addition to the hourly charge, unless supplied by other. Cleaning by the square foot, the chemical could be included in the bid or as an add on. Until proficient in estimating the amount and cost of the chemical when cleaning, it is best to have it remain as an add-on to the bed.

Mildew Treatment

Mildew is a fungus and although stubborn to remove, there are several methods that remove it. Improved "mildewcides" products, which contain mercury derivatives, are now on the market. If mildew problems are on exterior walls, roof, etc., spraying with these products kills mildew on contact. It cleans away old stains and the manufacturers claim it keeps mildew away for up to a year.

If spots form on exterior wooden walls, this suggests the wood was not properly seasoned before painting. One option is to dissolve a half-cup of trisodium phosphate (TSP) powder in a gallon of water along with one cup of ammonia. This kills mildew and paint can be applied over existing coat without fear of recurrence. Rinse thoroughly and let dry before applying paint. Household bleach may be used in place of ammonia, though it may bleach paint and cause damage to plants.

Another choice would be mixing 2/3 of a cup of household cleaner, 1/3 cup of powdered all purpose detergent, 1 quart ammonia, and 3 quarts of warm water. Leave on until mildew is gone and then rinse with clear water. The aforementioned remedies also remove mildew from surfaces other then wood.

CAUTION: Do not mix detergents that contain ammonia with beach. The combination of the two can produce a toxic gas.

The removal of mildew with water and pressure washer is a temporary solution only. The solution does not kill mildew. If removal were from wood siding, as on a residence, damage to the siding would offset any benefit derived from removal with this method. Use a scrub brush to scrub the stained area and then flush thoroughly with a garden hose.

Mildew stains do not normally cover a large area, although there may be several stains in different locations of the structure. Use the base price of forty ($40) to fifty ($50) dollars an hour whenever bidding mildew removal. Whether to include the cleaning agent in the base price or to add it is the operators decision.

Moss Treatment

Before committing to the use of pesticides in the treatment and removal of moss, check with the state-licensing department on regulations in the handling and applications of pesticides. Some states require each applicant to pass an examination on the handling and application of pesticides before issuing a license. This license is required in addition to a state contractor’s license. Unless you have this license, DO NOT attempt to apply such treatment. Because of the toxicity level and corrosiveness of such chemicals, you are exposing the general public to health hazards. The use of pesticides in the treatment of fungi and moss is definitely not a do-it-yourself project.

Temporary removal of moss can be accomplished with the use of a pressure washer. This procedure does not kill the moss or fungi and it will return. A garden hose lacks sufficient pressure to remove it.

Here is a checklist to assist in diagnosing a roof’s present state and spotting any possible future problems. Timetable and conditions may vary due to product and environment.

Roof Age and Visible Symptoms:

2 years – Weathered, silver in color.
4 years – Darker gray, fungi appearing.
5 years – Natural preservative in the wood is gone.
7 years – Roof turning black, moss build-up in shaded areas.
10 years – Deterioration visible in butts.
12 years – Deterioration 1" up the shake or wood shingle.
15 years – Deterioration 3" up the shake or wood shingle.
16 years or older years – Roof needs replacing.

The following is a synopsis of situations that enhances the growth of moss and fungi. Moss is any of various; very small, soft, green or brown plants that grow together like a carpet. It grows on mortar joints, moist roofs, moist sidewalks and in other constantly wet or shaded damp areas. Anyone living in an area that has a climate similar to the Pacific Northwest is familiar with the presence of moss on roofs, sidewalks, etc.

It is apparent from the amount of moss build-up on roofs of houses, sidewalks and other structures, that many people are not aware of how destructive it is. Deterioration can be so severe that repairs cannot correct some situations, which makes replacement necessary. If conditions continue to exist which contributed to moss growth initially, control is only temporary.

Moss growth on mortar joints causes deterioration of the mortar. Eventually, the deteriorated mortar requires removal and replacement. Application of waterproofing material on brick masonry and other masonry structures does not eliminate the accumulation of moss. It may, however, prevent damage from accumulation of moss for several years. Once deterioration sets in, repair damaged areas, pressure wash, and reseal. Follow manufacturer’s instructions for proper application of sealer.

Pressure washing to remove debris, leaves, and pine needles from over hanging or nearby trees assures better drainage of rainwater. It is not always desirable or possible to eliminate over hanging or nearby trees. However, it is important to keep the shingles clear. Pine needles trap and contain water that causes leaks and allows moss to grow.

Moss killing chemicals are the most effective method in killing moss and inhibiting its growth. The length of time they are effective depends on type of chemical used, type of roof, rainfall, and depth of chemical’s penetration. Application of these chemicals during the growth cycle is most effective. Achieve maximum control by applying chemicals to a dry surface, when the forecast is for no rain for several days.

The following solution for removal of moss and mildew stains on fiberglass panels, asphalt and fiberglass shingles may be used without a special license. Spray a mixture of three quarts of a bleach containing sodium hydroxide and one quart of water to each fifty (50) square feet. Some brands of bleach do not contain sodium hydroxide or contain insufficient quantity to be effective. This solution kills the growth immediately if applied as stated.

Flush metal gutters during and after the treatment to prevent corrosion. Cover vegetation with plastic and thoroughly flush the vegetation and the surrounding areas with clear water when finished. Do not rinse the roof before or after the treatment. Use extra precaution on roofs, as they are very slippery from the fungi and the solution makes them even more so.

The solution is caustic, so wear goggles and other protective gear when working with or handling the solution. Flush the solution from the skin with clear water as soon as possible to decrease possibility of burns.

If the conditions that contributed to the growth of fungi have not been improved or corrected, the length of time the treatment is effective varies. If further applications are required within the next two to three years, apply the following solution: One quart of bleach to nine quarts water. To keep area free of growth, apply the aforementioned solution yearly there after. To reiterate, DO NOT apply pesticide treatment unless you are a qualified, licensed, bonded and insured contractor.