The Finish Line: Cleaning EIFS
An EIFS finish coat is a textured, paint-like material. It’s usually made with acrylic resins or a blend of acrylic resins and other resins, such as silicones. The hardness of the coating and its textured surface make it susceptible to getting dirty. Depending on what the dirt is, it may or may not be easy to remove it. This month’s column is a compendium of various methods for removing a number of common types of surface conditions, such as dirt, oils, rust and so on.
First, an EIFS finish coat is not rock hard. It is like a thick paint but is not so hard that it cannot absorb dirt into the surface itself. In fact, when the EIFS finish gets damp, it softens slightly, and microscopic dirt particles can become embedded into the surface and locked in there. In other words, the dirt is not sitting on the surface but is within the surface. When the finish coating dries thoroughly, the locked-in dirt often cannot be removed by scrubbing or chemicals. Then, what do you do?
The usual approach is to paint over the dirty area. Applying a whole new layer of EIFS finish involves leveling the surface with an EIFS basecoat adhesive, and applying the new finish; painting is easier. Painting involves cleaning the surface thoroughly of any loose material (by scrubbing with water, detergent and a stiff bristle brush, and then flushing it and letting it dry) and then applying a compatible paint. EIFS producers make a non-textured paint version of their finish coating that can be used for this purpose. Exterior grade water-based acrylic house paints will also usually work.
This problem of embedded dirt is the reason EIFS producers want steep slopes at window sills and similar areas-so that water will run off and not leave water-bound dirt in the crevices of the surface. Some EIFS producers offer finishes with special resins that exhibit inherent reduced dirt retention. They sometimes have “Dirt Pickup Resistant” versions of their regular finishes.
If surfaces such as large shallow-sloped window sills keep getting dirty, one way to at least partially mitigate the dirt pickup is to seal the surface with a high-build, hard clear coating, such as an acrylic. This type of coating tends to fill-in the texture grooves, thus leaving fewer little valleys for dirt and water to lie in. The extra hardness also helps keep the surface from absorbing dirt, therefore partially getting around the problem described above of embedded dirt. You only need to apply such sealers on the affected area, such as at windows, and not the whole wall. Such areas are not fully visible, so the slight change in the appearance of the surface is barely noticeable.
WHAT NOT TO DO
Pressure washers can be used to clean EIFS, if used carefully. There are several problems, though. One is that high pressure can drive water through the finish and basecoat, and into the insulation. This can take awhile to dry out and reduces the effectiveness of the insulation. Another problem is that high pressure can strip off the finish from the basecoat. Yet another is that if steam is used, it can melt the insulation if the insulation is the thermoplastic EPS type. The trick is to use a lot of water flow, but not much pressure.
You definitely do not want to use sandblasting, as it will strip off the EIFS finish.
Using solvents to remove paint or oily stains can wreak havoc with an EIFS. Many solvents can leech through the finish and basecoat, and then dissolve the insulation. Companies like Demand Products make specialized EIFS-friendly cleaners that can take off various surface contaminations, like paint and oil.
MOLD AND MILDEW
A diluted solution of household bleach and warm water, combined with a stiff bristle brush, will usually remove mold and mildew. Do not use too much bleach, as it can lighten the color of the finish.
Rust can become bonded into the surface of the EIFS and can be a real bear to get rid of. Luckily specialty rust-removing chemicals are available that are compatible with EIFS. If the rust source can be eliminated-such as a rusting steel bolt that is in contact with the EIFS-then the rusty area can be painted over to hide the rust stain.
If a rust stain is due to an iron particle that is embedded into the finish, the key is to dig out the particle and then remove the stain. Painting the particle does not work, and the rust will bloom through the paint and start the staining process all over again. A nut picker works well for digging out rust particles. It’s amazing how an iron particle the size of a pinhead can make an ugly, dark rust streak several feet long.
Sticky, heavy-bodied materials, like roof tar and diesel soot, can fill the texture of the EIFS finish and be darn near impossible to remove; painting over them doesn’t usually work as the paint will not stick to the tar or oily soot. In such extreme cases, the affected area may need to be fully removed and rebuilt. Stripping off the EIFS lamina usually mangles the insulation, requiring that layer to be removed as well. The repair technique is similar to that used when repairing impact damage, namely splicing in a new area of EIFS, from the substrate out.
Efflorescence is the deposition of salts on the surface of a wall. It is not uncommon with materials that contain salts, like brick mortar and Portland cement products like stucco and EIFS basecoats. In the case of EIFS, the presence of efflorescence is usually in the form of a whitish powder. The presence of efflorescence means there’s water coming from behind, which is not a good thing. It can also mean the EIFS finish is porous and outdoor water takes unbound salts in the basecoat and deposits them on the finish as they dry. Clearly water-in-the-wall can be an indication of leaks and other serious matters, so the cause of the efflorescence needs to be determined as part of the cleaning process. Efflorescence stains tend to go away with time but often owners want them to disappear sooner. In that case, there are specialty cleaners that work on EIFS and do not damage it but are not as harsh as the cleaners used on tough materials, like masonry.
Sometimes, the owner wants to paint over a dirty wall that won’t come clean by scrubbing or using cleaning solutions. The idea of using a harder, high-performance specialty paint, such as a urethane, is considered a way to make the EIFS finish less susceptible to future dirt pick up. The problem with this approach is the heavy-duty specialty paints are highly water-vapor resistive and seal up the wall surface too tight, essentially creating a vapor barrier on the outside of the wall. In cold climates, water vapor that is trying to permeate through the EIFS to the outdoors can get trapped where the basecoat meets the insulation. This can cause the basecoat to debond from the insulation, much like you see on older homes with wood siding and multiple layers of paint: you get blisters. Many high performance paints are also solvent-based (rather than water-based) and the solvent can pass through the EIFS lamina and dissolve the insulation.
ONGOING CLEANING PROBLEMS
The architectural design of the termination of non-EIFS materials at the perimeter of the EIFS is sometimes the cause of ongoing staining. A common example is a poorly designed parapet cap flashing that dribbles dirty rain water down the face of the EIFS. A simple redesign of the flashing can keep the water from contacting the EIFS in the first place, eliminating the problem once and for all.
Sometimes, EIFS buildings develop chronic cleaning problems. Examples include cool damp areas where mold abounds, and EIFS installation in dirty areas, such as where vehicle exhaust constantly gets on the wall surface, such as at bus stops and loading docks. Often there is really nothing you can do about the source, and it’s simply a matter of routine maintenance to keep the wall clean.
There are some situations done to keep the wall cleaner looking, such as:
- Keeping shrubbery away from the EIFS. This includes sprinkler patterns that wet the EIFS walls.
- Keeping the EIFS up and away from dirt-producing surfaces such as sidewalks, and planted areas, where water splashes up onto the EIFS.
- Keeping signage off of direct contact with the EIFS surface. Standing off the sign an inch, using spaces or a bracket, is all it takes. Flush-mounted signs tend to trap and divert dirt-laden rainwater to their ends, causing large streaks.
- Using metal flashings with a drip edge at window sills and parapet caps.
Many EIFS producers offer published guidelines on how to maintain their products. It would be wise for EIFS contractors to provide this information at the end of the project, as many owners do not really understand what EIFS is and how to maintain it. For instance, they tend to treat EIFS like a much harder material, such as stucco or a textured coating over concrete. Clearly this approach can damage the EIFS. Sometimes the project’s specifications call for providing maintenance information via the Submittals section of the spec. As for cleaning EIFS this article would be a good starting point to inform customers of maintenance procedures, if you can’t get your hands on the manufacturer’s maintenance guidelines. W&C