Wood Siding -Wood siding could be either made of shakes, T1-11, or lap siding. (Wood restoration is covered in another course.) Typically when this siding needs to be cleaned it may need to be restored or painted. It is important when cleaning wood siding to use very low pressure so as not to chip paint or remove a coating from the wood. Wood coatings typically last 5 years or more depending on the coating before a re-application is necessary. Painted surfaces that are properly primed can last significantly longer. In between, the exterior will need to be cleaned and the same rule above applies about pressure and cleaning solution strength. Wood siding is easily scarred, so also be careful about how close you are to the surface. Start out approximately 12 inches from the surface and get closer as necessary. Commercial Restorations provides professional services to commercial, industrial and residential properties in Maryland since last 32 years. 
Stucco – Stucco is a material that is made of an aggregate, a binder, and water. This mixture is then applied to a surface in a wet state and allowed to dry. As it dries it hardens and is often used over concrete, blocks, or steel. Lime is often added to modern stucco to increase permeability and workability. Stucco often has color mixed into it, but always test your cleaning solution in a hidden area since some stucco is painted (which usually calls for a gentler cleaner). Stucco cleaning is quite different from other surfaces. It is rough and highly porous so it will hold dirt and mildew more than other surfaces and it also has a tendency to pull cleaners into the surface making it difficult to rinse. Stucco (unpainted) is a stronger surface than most you will clean, and can be washed with pressures up to 600 PSI. Stucco needs periodic cleaning to remove surface oils and stains from tree sap, insecticides, pollutants and growth from mold and mildew, etc. to prolong the life span of the product as well as to keep it looking nice. This is why more frequent, easier cleanings are recommended. Allowing the surfaces to build up with pollutants, mold, mildew, etc. means more aggressive cleaning which is not as desirable for stucco surfaces.
Stucco surfaces can be tricky because of their sensitive make up. It is important to hand scrub problem areas prior to washing and rinsing the entire structure. This should give you an even, desirable outcome. Scrubbing problem areas after the building has been washed causes those areas to be more pronounced. Some projects require all hand scrubbing and should be evaluated at the time of the proposal. Problem areas on stucco are frequently around window frames and gutters.
NOTE: Be certain that the stucco surface you are about to clean is real stucco. Usually you can tell real stucco from artificial stucco by simply rapping on it with your knuckles. If the knock produces a hollow sound, it is artificial stucco. Called a number of different names in different parts of the country (such as EIFS or Dryvit) artificial stucco is a skim coat of stucco cement placed over a foam substrate. Imitation stucco is difficult to work on because any excessive pressure will damage it extensively. Additionally, artificial stucco forms surface cracks over time where water under pressure can enter and cause extreme maintenance issues such as mold. To clean artificial stucco, keep your pressure under 600 PSI and use cold, unheated water. Hold sprayer with a fan-tip nozzle at a 45° angle from the wall (not perpendicular) and keep spray tip at least 2′ 0″ from surface. Also, do not use abrasive hard-bristle brushes and do not apply physical force to this delicate surface.
Brick / Masonry – Brick and Stone Façade cleaning is also different from other surfaces, even stucco. Brick, for example, is highly porous and has a tendency to pull cleaners into both the bricks and the mortar. This makes it difficult to rinse completely. Stone surfaces may be very hard or very soft, porous or non-porous. Always test your cleaner and cleaning method in an inconspicuous area before proceeding. Don’t make the common mistake of assuming you can use higher pressure to clean these surfaces. Most brick and all mortar is softer than it appears, and high pressure can etch the surface or even cause pieces to be broken off. These substrates should also be cleaned with low pressure (600-900PSI).
Other Surfaces – All surfaces, painted or otherwise, need periodic cleaning to remove surface oils and stains from tree sap, insecticides, pollutants and growth from mold and mildew, etc. to prolong the life span of the product as well as to keep it looking nice. It is important to evaluate the substrate and know how durable it is. How deteriorated is the surface or coating? Does it need to be hand scrubbed? Will it be able to withstand 1000 PSI or more? Will it require less than 1000PSI? Are there stains that need to be addressed prior to cleaning? These questions not only need to be answered for the estimate to be properly done but, also communicated to anyone else who may be performing the work on that particular structure. It is important that if you are unfamiliar with a substrate or exactly how to clean a structure that you get the answers you need prior to starting the job. “After the fact” is usually too late.
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