Rob offers several tips how to clean EIFS.

EIFS needs to be cleaned for various reasons. Obviously, it can make it look better. Other reasons include preparing it for changing its color by painting it, and preparing it for applying a new basecoat and finish to it. Cleaning the wall before applying a new coating is critical in the last two cases. The reason is simply that the only thing holding the new materials onto the old finish is the bond between them. A clean surface is essential to achieving that bond. Remember that cleaning involves not just removing whatever is on the wall to start with but also whatever residue is left by the cleaning process itself.

The usual way to get plain dirt off EIFS is to scrub it with a bristle brush using warm water and mild soap. EIFS finishes are water-based, and when they become wet in the normal course of their existence as a wall material, they become slightly softer. In this softer condition, tiny particles can get lodged into the finish. When the finish dries again, these particles become part of the finish. These particles sometimes simply do not come off. More aggressive cleaning methods are needed.

Less is more

People say not to use pressure washing to clean EIFS. That’s not true. What one has to do is to be careful and not get wild with the wand. Use a lot of water at low pressure, rather than a little water at high pressure. Most people I talk to use between 500 and 800 psi. A washer that has control for the pressure and spray pattern is helpful. If you crank up the pressure, not only can you damage the EIFS finish, you can also drive water through the EIFS lamina. This can soak the foam behind it. It then takes forever to dry. Meanwhile, this wetness reduces the energy efficiency of the insulation. Also, if the EIFS is in a cold climate area, the water behind the lamina might freeze. This can damage the foam-to-lamina bond and can crack the lamina.

When pressure washing, be careful around windows, openings and flashings. You can easily force water through the joints at these locations. This can occur even with windows that are normally watertight: They just are not designed to withstand that much pressure.

When washing with water, watch the water temperature. We’re talking about pressure washing here, not steam cleaning. Using hot water can affect the EIFS foam insulation behind the lamina. Many EIFS use EPS for insulation and EPS has a maximum service temperature well below that of steam.

While pressure washing can be used to clean EIFS, sand blasting should not. I’ve tried it and it’s simply too harsh. It’ll strip off the finish and gore the basecoat, and is too difficult to control.

When washing, start from the top and work downward. Be careful about where the runoff water is going. This is especially true on tall buildings and under windy conditions, where the water is somehow magically attracted to lawyers’ cars. Because the act of washing in itself means that the water runoff contains some kind of dirt, it also means that whatever surface the runoff water falls onto may also get dirty. It’s not that simple, however.

Some forms of “wall dirt” contain residues from the environment that can damage common surfaces. Troublesome materials include hydrocarbons from combustion processes, as well as caustic and acidic materials. For example, water runoff can even etch window glass, which is virtually impossible to repair except by replacing the glass. Runoff can also leave stains on architectural materials, such as painted or anodized surfaces, as well as on paving, shrubbery, little old ladies and their precious poodles. The moral is: Protect the entire work area.

Algae and mildew can usually be removed by scrubbing. The addition of bleach to the scrubbing water can help a great deal. Keep in mind, however, that the mildew or algae will probably return. This is because the algae and mildew feed on the microscopic nutrients that become trapped in the texture of the EIFS finish. Thus, this is an ongoing maintenance issue. Also, make sure not to use too much bleach. Doing so may lighten the color of the EIFS finish. EIFS manufacturers have information that gives correct ratios. Lastly, use care using phosphate-based cleaners. You need to get all of such cleaners off, lest you end up later with even more mildew or algae. This is because traces of phosphate materials that are left on the wall, literally acts like fertilizer.

Nasty stains

For really obnoxious stains, such as tar or graffiti, one may be tempted to use a solvent. Be careful. Many solvents generate fumes or contain liquids that can leach through the EIFS lamina and attack the foam. This can debond the lamina from the foam.

In some parts of America, especially the southeast, red clay stains can be a real problem. These stains can be especially hard to get off. It’s worth the time to protect the bottoms of EIFS walls from clay getting splashed up on them.

Treated wood can cause problems, too. The treatment chemicals sometimes leach out and onto the EIFS, and are essentially impossible to remove. Decks and parapet caps are primary offenders. For practical purposes, painting over them is the only way out.

As a last ditch effort one can paint the EIFS finish. This presents some challenges. For example, graffiti is often very difficult to remove for various reasons. Many spray paints are solvent based and the paint literally becomes part of the EIFS finish. It is not a topical residue but becomes built-in. Being sprayed, it also gets into the tiniest nooks and cracks. Graffiti usually needs to be “painted out.”

One of the big issues with painting is that if you just paint where the dirt is, you’ll be able to easily spot the painted area. This occurs even if you get an exact color match. Remember that painting tends to fill-in the surface, making it look smoother. Usually, if painting is the method of choice, you must paint back to a natural line-of-sight break in the wall, such as a corner, an opening or a joint. This sometimes involves painting large wall areas.

Also, some EIFS finishes contain chemicals that make them more resistant to dirt pick up, and thus also resistant to being bonded to by other materials, such as paint. In this case, identify whose EIFS product is on the wall and seek the manufacturer’s input on what types of paints will stick to its finish.

It’s also possible to seal the surface of the EIFS by using the wrong type of paint. Under certain climate and building use conditions, this can trap water vapor in the wall, leading to condensation-related problems such as soggy wood, damp insulation and mold. EIFS manufacturers can help you with this matter, as it requires engineering analysis.

Some paints contain solvents that can leach through the EIFS lamina and degrade the EIFS foam insulation. EIFS manufacturers make paint versions of their finishes, and these are often the best choice for painting their own products.

One of the chronically bad sources of stains is window sills. Some sills are made of EIFS itself, while others have flashings that lack drip edges, thereby depositing dirty rain water onto the EIFS. In the case of sills made of EIFS, a steeper slope, combined with a smooth EIFS finish, will help the water leave the sloped sill surface. Also, the addition of a hard, clear sealer to the sloped EIFS surface will also help it shed water.

I’ve had homeowners ask me if they can use a blow torch to burn off stubborn stains. That may work on roofing tar or concrete but with EIFS you may set the building on fire. Don’t even think about it. The EIFS lamina contains plastic resins that can burn and the foam plastic insulation behind the lamina is combustible.

Of course, for really ornery stains, you can always remove the whole EIFS back to the substrate and replace it all, and then blend in the new EIFS with the old. For instance, if gooey mastic is on the EIFS, even if you can somehow dig it out of the EIFS finish, paint will probably not stick to it. So the only real option is removal and replacement of at least the EIFS lamina, if not the whole EIFS.

I’ve seen people try to cover a stain by applying new EIFS finish over the old finish with a trowel. This usually looks bad, as the texture of the existing EIFS affects the ability of the new EIFS finish to achieve a proper new texture. Usually, the way to attempt this type of repair is to skim out the existing EIFS finish to make it flat, using a cementless basecoat adhesive without reinforcing mesh, and then apply new EIFS finish on top of it.

When testing various cleaning techniques, try doing so for the first time at some inconspicuously location, such as on the non-public side of the building. Then, if somehow the technique isn’t successful, at least it will not be so obvious. W&C