Caring for Stucco, Manufactured Stone and Brick Veneer

Periodic Cleaning

Applied wall surfaces are generally self-cleaning when in contact with rain water. However, since most architectural designs include overhangs and soffits, parts of the stucco surface may be protected from this natural cleaning. To insure consistent cleaning, a simple water rinsing one to two times a year will keep the surface clean and the color bright. This can be done in three steps: (click here)

Pre-wet the wall, saturating it. Start at the bottom and work to the top.
Use a garden hose to direct a high pressure stream of water against the wall to loosen the dirt. Start at the top and wash the dirt down the wall to the bottom.
Flush remaining dirt off the wall to the bottom.

Cleaning Stains

Occasionally, mud stains (typically occurring at the foundation level) and stains resulting from extractive bleeding of wood trim may require more than a water cleansing. If these stains are treated at first notice, they can, in most cases, be removed successfully. To remove these stains, a solution of Trisodium Phosphate (TSP) and water, or a very light solution of Muratic Acid and water may be utilized. Both these items are available at hardware stores or building supply outlets. Some laundry detergents, such as Tide, contain TSP. With both of these solutions, a small inconspicuous area should be cleaned first to test the results.
When using TSP: 

Pre-wet the area and any area below it.
Make a paste-like solution with water and apply to the area with a stiff bristle brush.
Allow to remain for a short time.
Rinse thoroughly to remove any residue.

When using Muratic Acid: 

Pre-wet the area and any area below it first.
Mix in a plastic or rubber pail a very light solution. Add 1 part Muratic Acid to 18 parts water. Do not mix any stronger, as this may etch the stucco surface. Always add the acid to the water to avoid splashing or reaction when mixing.
Apply with a stiff bristle brush to the area.
Rinse immediately very thoroughly to remove any residue.

NOTE: Muratic Acid is highly corrosive and caustic. Protective goggles, gloves and clothing should be worn when using this material. Extra care should be taken to insure this solution does not contact any areas or materials other than the stained stucco, as unwanted damage could result. (Consult Material Safety Data Sheet) 
If either of these 2 methods fail to clean the area, you should call a professional.

Cleaning Mildew

Occasionally mold or mildew may occur on wall surfaces that consistently remain damp, and are not subject to sun drying (usually north facing walls). To clean these areas, pre-wet the area, scrub with a light solution of bleach (1 part bleach, 10 parts water), then rinse thoroughly.

Preventative Measures

Obviously, the best way to insure against dirt and stains is to eliminate their sources. Some preventive measures are as follows: 

Avoiding foundation mud stains: The perimeter of the structure should be covered with sod or, if seeding, covered with a protective layer of straw. Landscape areas should be covered with a layer of mulch, pea gravel, or decorative stone. This can help avoid mud splash up from heavy rains or watering. Insure roofs have a gutter system that is functional to prevent heavy concentrations of roof water runoff at the base of the stucco wall.
Windows and screens be cleaned periodically to eliminate dirt stains below the windows. This is particularly important with the absence of a protuding window sill to facilitate runoff.
Avoid contact of well water with the stucco surface when watering lawn or landscape areas. Well water contains minerals, such as iron, which can leave a rust residue. Use a soaker hose to eliminate water contact with stucco in these areas.
Avoid stacking firewood against the stucco wall with first protecting with plastic or other means. Oil stains, fungus and algae develop from contact with wood or bark.
Plant vines often have decorative effects when grown stucco, and are generally not harmful. Unfortunately, when vines die or are removed, tiny root burrs remain attached to the stucco and are extremely difficult to remove. Removal should be done by a qualified professional for best results.
Surface mounted metal objects, such as lights, mail boxes, house numbers, metal copings and metal chimney caps, should not be allow to rust onto the stucco surface. As rust is detected, prime and paint immediately. Rust stains are very difficult to remove from stucco.
For vandalism or graffiti, promptly contact a professional for cleaning instructions.
To help prevent extractive bleeding from wood trim, you must prevent any moisture from seeping in behind the trim. This can be done by insuring all possible points of moisture entry are caulked (between window frames and trim, at butt joints, and occassionally, at trim board and stucco interface). Use a good acrylic or silicone caulking and periodically inspect these areas to insure functionality.

Cracks

Hairline cracks are not uncommon in stucco and are no cause for alarm. These cracks are a function of the framing expanding and contracting with the seasonal humidity changes, and may appear and disappear with the seasons. A true hairline crack does not require any remedy. If the crack, however, should become greater than 1/8" in width or if you notice a shift in the wall plane, then you should contact a professional for advice.

Painting

Although stucco only requires periodic water cleansing, some conditions such as extreme staining or a desire to change color schemes, may prompt painting the stucco surface. If so, only use a high grade acrylic based paint. Use of oil base or inferior latex paints will produce undesirable results. Best results are obtained by employing a professional who is qualified in painting masonry surfaces.