Mold and mildew are a black/gray, green, red or purple growth that can form at certain locations on the building exterior. The growth of mold is more common in southern climates but can occur anywhere.


Mildew is a fungus that spreads as microscopic spores are carried by the wind. When the spores land on a surface, they feed either on the surface itself or on organic airborne dirt that has accumulated on the surface.The growth of mildew/mold is encouraged by moisture, warmth, organic nutrients, and darkness. (North elevations of buildings are susceptible in particular.)Since the spores travel through the air, their behavior tends to be erratic. During rainy periods, the mildew can appear on previously unaffected areas. To the unaided eye, mildew frequently resembles dirt.

Mildew and mold like warm, moist, shady locations, such as under eaves, near or behind bushes, shrubbery and trees and on soffits and walls that are frequently shaded from the sun. However, during humid and/or rainy periods, mil-dew/mold can obtain a foothold on virtually any exterior area.

Cleaning Recommendations

Option No.1 –   Pre-wet the area with clean water and wash with a solution of three (3) parts water to one (1) part household bleach. Apply solution and let set of 15-20 minutes. Do not let solution dry on the surface. (A mild liquid detergent or soap may be added to this solution to improve cleaning ability.)

Use a soft bristle brush (non-metal) and gently scrub the affected areas. Rinse thoroughly (use low pressure lawn and garden type hose) and repeat as needed. Note: Water down all shrubbery, trees, and flowers near areas where the solution is being used. Wear protective eyewear and protect your hands and arms with gloves and a long sleeve shirt as necessary. Before adding a liquid detergent to any household bleach solution read the labels to see If they contain ammonia or ammonium compounds. Bleaches should never be mixed with any detergents or cleaners containing ammonia. These-mixtures can cause harmful vapors. Follow all instructions on the label.

Option No. 2  –  Use available commercial cleaners specifically formulated to clean mold and mildew from Exterior Insulation and Finish Systems.

Recommendations to Avoid Mildew

1. Mildew/mold is an organic growth supported by warm, moist, shady conditions with the following contributing factors:

        A. Climatic conditions: mold/mildew is more significant in a warm humid environment.

        B. Texture of finish: coarse textures will collect more airborne dirt with potential organic nutrients than finer textures.

        C. The proximity of shrubbery and trees: creates shade and reduces air circulation. This reduces natural evaporation.

         D. Poor drainage from roofs: will maintain a high level of moisture in designated areas.

         E. Internal moisture within Exterior Wall Systems: will maintain a high level of moisture in designated areas. This may be from internal condensation or physical leakage.

As indicated, each of these conditions are contributing factors to mold/mildew. The climatic condition is an environmental issue, however, the locations for trees and shrubbery in southern climates may be positioned away from the building, particularly the north elevation to promote natural air circulation for natural evaporation.




The accumulation of dust and dirt in many locations can be a constant maintenance problem. Some contributing factors are as follows:

A. Site conditions – sources of dirt

B. Soil splashing against the system

C. Climatic conditions (sun, rain, wind, or temperature extremes)

D. Building location

        1. City (high density- significant vehicular traffic and manufacturing with resultant airborne pollution)

        2. Suburbs (low density- minor airborne pollution)

        3. Near industrial manufacturing facilities

E. Amount of precipitation or rain (insufficient rainfall to be effective for normal self-cleaning action).

F. Exhaust venting onto finish areas.


In general wind born dust and dirt is an inert accumulation that can possibly contribute to the discoloration of EIFS.

Typically, this is an aesthetic issue and will not affect the overall performance of the EIFS.

If it is suspected that a “chemical contamination” is a contributing factor to the discoloration then a sample should be forwarded to an independent test lab to determine the contaminate. This information should then be reviewed with the EIFS manufacturer.

Cleaning and Prevention Recommendations

Option No. 1 For dirt accumulation at the first floor/ foundation from splash-back due to uncontrolled drainage from the roof.

*The cleaning procedure should consist of a household liquid detergent mixed with water.

        1. Pre-wet the affected areas

        2. Apply soapy water with soft bristle brush, scrub gently, let set for15-20 minutes. (Do not let solution dry on surface.)

        3. Rinse off thoroughly with low pressure garden type hose.

*Try the cleaning procedure in a small inconspicuous area to make sure it does not adversely affect the EIFS.

For more stubborn stains, it may be necessary to use a stronger cleaner formulated for EIFS.

Prevention of splash-back: Remove a layer of soil next to the foundation and replace with a layer of crushed stone or other mulch material to prevent splash-back of water onto the building.

Option No. 2  –  This is for general airborne dirt accumulation. An evaluation should be made when it is aesthetically desirable to clean the entire building.




Reddish colored staining typically originates as a metallic stain from excessive chemicals or iron oxides, contained in the local water supply. This discoloration is a result of a stain from sprinkler overspray on the exterior wall system.


These areas of discoloration generally are an aesthetic issue only. They can be removed with a commercial cleaner formulated for EIFS.

The longer these types of stains remain, the more difficult they will be to remove. In two-three years, these stains may become permanent. If the stains are permanent, it is necessary to neutralize the stains to prevent bleed-through and re-coat the affected area.

Recommendations to Avoid Lawn Sprinkler Overspray

I . Readjust or relocate the sprinklers that are the cause of the overspray.




EIFS is a monolithic, barrier wall-type system, sometimes also referred to as a face sealed system.

The integrity of this barrier must be maintained with a correctly performing sealant joint at all dissimilar materials (i.e., windows, doors, louvers, etc.), to prevent moisture intrusion.

If the sealant is not maintained through some type of minimum Preventative Maintenance Program, water infiltration problems may occur over time.

The life expectancy of a quality, correctly installed sealant material is 3-5 years under severe ultra-violet (sunlight) and weather extremes. In less than severe conditions, 8-10 years is likely before replacement should be considered. (Consult the sealant manufacturer for the additional information.)

Recommendations for Observation of Sealant Joint Performance

EIFS when correctly detailed and properly installed does not allow water migration through the wall.

The water migration (leaks) will typically occur at one of the following:

I. Failure of sealant at building expansion joints.

2. Failure of sealant at transition to dissimilar material

        A. Flashing component

        B. Window/head, jamb or sill

        C. Louver/Head, jamb or sill

        D. Penetration through EIF System

        1. Handrail connection details

        2. Electrical conduit

        3. Utility Piping

                  4. Etc.

All leaks should be documented as to their location and whether they appear in gentle rains, or wind driven rains and from what direction. Also, determine how long the leak continues after the rain stops.

This information, in conjunction with a thorough observation of the exterior wall system, will assist in quickly locating the source of the leak for remedial repairs.

Field “Trouble Shooting” Guide

1. Observe the joint. There should be a uniform bead of sealant (uniform in width and appearance.)

2. Observe any separation within the sealant joint.

        A. Adhesive failure – separation of sealant from dissimilar material.

        B. Cohesive failure – separation of the sealant internally.

3. Observe aging. This is a progressive, natural change in the chemical and physical properties of the sealant material.Two-part Two-part olyurethane type sealants are self-sacrificing. The surface is constantly wearing  away and appears as a chalking or oxidation type film that is constantly washed away by rainstorms. This is normal for this material and does not indicate failure. Two-part polyurethane type sealants are self-sacrificing. The surface is constantly wearing away and appears as a chalking or oxidation  type film that is constantly washed away by rainstorms. This is normal for this material and does not indicate failure.                                                                                      

4. Observe any discoloration and/or bleeding.

This may represent a defective product defective product deteriorating.

5. Observe deformation.

This is any change of form or shape produced in a body by a stress or force.

6. Observe cracking, crazing or “alligatoring”.

These conditions represent a deterioration within the sealant joint induced by either excessive movement or aging.

Please contact the EIFS manufacturer for any additional information.

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