Washing EIFS

September 2007

Your client wants you to clean his small 15-year-old commercial building, which is clad with an exterior insulation and finish system (EIFS). The exterior has no major damage; it just needs a good washing. What’s the best way to do this? What chemicals are best? Would you use a pressure washer to rinse?

I would have to look up and follow the cleaning procedure that the manufacturer has in his specifications for the installed product.
—Jonathan Diepstra, Estimator, Grand Rapids, MI

There are various chemicals on the market that would do the trick, but you must be very choosey, especially when dealing with an acrylic finish that is 15 years old. [You could use a] simple solution of cold water and white vinegar (4:1 ratio) for a more soiled surface, or water and baking soda (5 gal. to 2 lbs. approximately) for lighter cleaning. Southern red clay may require commercial chemicals—again, be careful; make sure it is safe to use on acrylics. (Environmental issues with various chemical cleansers should also be a major concern because of runoff and ground absorption.)

A pressure washer can then be used for thorough and efficient rinsing, but should be kept at low pressure (300 to 400 psi is plenty) as not to harm the aged acrylic finish. If you do, also be very careful around window and door openings. Caulking may (if not already) become detached or damaged and require replacing.
—Aaron Ford, Purchasing Agent, Precision Wall, Inc., Cary, NC

We would fix any small damage, if there is any, to make sure of no water penetration through the skin of the system. Then we would check the caulking to make sure it is not breaking down and is still making a good seal around all penetrations. When it comes to what kind of chemicals to use, we would use liquid Dawn® dish soap with a blend of Clorox® and water. Yes, we would use a pressure washer to rinse the walls. We would use a 30 degree wide nozzle at a distance from the wall of 3 to 5 feet or farther (not closer) to rinse the wall. You would wet the wall first before any cleaning solutions can be applied to the wall. If you have any stubborn stains, use a soft bristle brush with the cleaning solution, then rinse off with pure water.
—Don Delahoussaye, Vice President, The Delahoussaye Co. Inc., Lafayette, LA

We have been cleaning exteriors for 20 years, and we use a variety of cleaners that we have specially made for us. One cleaner we have made for us is called EIFScrub. It contains, among other things, potassium hydroxide. We dilute this down anywhere from 2 to 1 to 15 to 1 depending upon how dirty and stained the EIFS is.

We spray this on with a low volume sprayer from the bottom up. We then rinse from the top down with a power washer. We use a flat nozzle spray for a uniform spray pattern, and we use low volume and low pressure (1,200 to 1,800 psi). You must be very careful not to use high pressure as high pressure will damage the EIFS exterior and force water into the EIF system as well as any openings like caulk joints, mitre joints, holes uncaulked soffits, utilities, penetrations, etc. It is the chemical that does the cleaning, not the pressure on the pressure washer.

For heavy stained areas we use a stronger concentration of EIFScrub or even some masonry restoration cleaners (depending on the stains), and use a soft brush to lightly scrub the stained area. We have rust cleaners for removing rust, paint strippers for removing a variety of paints, caulks, graffiti, roofing tar etc. or other things splashed on the EIFS exterior/finish. It takes some testing and practice with these other chemicals and strippers so that you do not use too strong a solution and don’t damage the EIFS you are trying to clean. We have had very good success with cleaning and restoring EIFS exteriors over the years.
—Joseph Serdar, President, American Restoration Ltd., Northbrook, IL

We at Robey, Inc. have found a very simple process that is effective, efficient and affordable. We start out by saturating the wall to be cleaned with clean water. We then mix a solution of a TSP (trisodium phosphate, or liquid bleach), bleach and water. We do not recommend the use of pressure washers due to the risk of damage to the already "tired” system. We use backpack sprayers. We mist the walls, gently scrub the wall with a soft bristle brush and rinse with clean water. A wall that is very soiled or stained may take several applications (not all stains can be removed). The TSP and bleach act in concert to both kill the mildew and remove its characteristic stains and remove dirt. We then highly recommend a sealer to be applied to the now clean wall. Much caution has to be taken into account in regard to the use of this solution; TSP and bleach solution can damage metal, painted surfaces, woods and landscaping.
—Gary Robey, President, Robey, Inc., Westminster, MD, www.robeystucco.com