What is House Washing?

House washing is the process of removing mold, mildew, dirt, grime, and oftentimes rust and soot from a home's exterior surfaces by using a combination of low to moderate water pressure and specialized detergents, algaecides and surfactants. While a house wash can be a DIY project for some, soliciting the help of a house wash professional can streamline the work while ensuring the proper chemicals and pressure is applied to the effected areas. Below are the most important factors to take into consideration.

The first thing to consider prior to washing any house is the proximity of delicate plants and flowers that may be effected by overspray. While the concentration of most house wash cleaning solutions are harmless to most Texas plants and shrubs, certain areas may require the use of "hotter" mixes.

For example - the typical bio-friendly house wash solution consists of 1.5% sodium hypochlorite combined with a surfactant, or soap. This is the same solution strength recommended for cleaning a child's playground and is also harmless to most all plants.

Areas that may be heavily infested with mold or black algae, or has a greater porosity (i.e., porous surfaces such as Stucco) might require a stronger mix of up to 3% or more. While this too is typically harmless to most plants, more delicate plants like ornamentals will need to be covered with a breathing membrane, such as Tyvek*.

*As a side note, this process is far less utilized during a typical house wash than it is for roof wash where the cleaning solution is 5-6 times more concentrated with sodium hypochlorite than what is required for a house wash.

The effect of chemicals on plants is exacerbated by high temperatures. This is because a plant's "uptake" of water -- or any other liquid that comes into contact with its leaves during hot drought-like conditions is much greater. To minimize this effect, all plants should be thoroughly hydrated prior to applying cleaning solution, and again after. This will ensure that plants are protected from injury during the cleaning process.

The first thing to consider prior to washing any house is the exterior surface materials. Is it brick, Hardie siding, stone, vinyl, Stucco or wood? Or is it a combination of these? This will determine the algaecide detergent strength or mixture ratio. A typical house wash solution will typically be between 1% to 3% sodium hypochlorite (commonly referred to in the industry as “SH”) to water. Smooth surfaces use a lesser strength, whereas material with porous surfaces such as brick and stone would typically use the higher mix ratio of 3% or more.

It's important to take caution and not apply too much pressure to windows when pressure washing your home. High-impact windows are capable of withstanding water pressure whereas windows with a low resistance rating would not. Specialized attachments specifically designed for window cleaning help control water pressure and avoid accidents.

This is where surfactants come in. Surfactants, often referred to generally in this industry as “soap” is added to the cleaning solution. Surfactant serves two main purposes. The first is to facilitate extended dwell times by keeping the solution wet for a longer period of time. The second is to keep the solution from running off the surface too quickly. Surfactant is applied via a metering valve that sits just behind the chemical pump and allows the applicator to add more or less to the chemical solution depending on the application.

The final step, and arguably the most important step among all the previous steps is rinsing. Water volume, water pressure, spray pattern, and spray uniformity can make the difference between a spot-free surface and a surface with an uneven or "penciled" finish.

"Penciling" refers to a pattern created by a spray nozzle that uses either too much pressure or an overly concentrated stream of water which removes top surface residue or oxidation in an uneven manner. An illustration of its appearance can be seen in the photo and is a clear indication of inexperience. Imagine this on the side of your house!

Can if fixed? Usually, yes. With a fresh application of solution and in some cases a light agitation with a soft bristle brush, followed by a proper rinse as described below, the surface can usually be repaired.

To rinse a house properly, a relatively high-volume of water not to exceed 300 psi should be evenly applied starting at the top and working down. The objective is to remove all remaining chemical and soap residue. Failing to do this correctly can leave a dull, chalky finish... not to mention an unhappy customer.

It's vital that you hire the right house wash professionals for this job because improper washing can cause expensive damage to siding, windows, and more! This will be evidenced by “pencil striping”, flash oxidation, chalky residue, damaged door and window seals, and damaged or discolored paint (especially on Sherwood Williams Organic Paint), just to name a few. The worst part is that all of this is 100% avoidable with the right equipment, the proper cleaning methods, and the most experienced professionals.

As you can see, a thorough house washing is a task that typically requires professional help. Klein Pressure Washing has the equipment, experience, and know-how. We’re available to give you some helpful advice and provide expert guidance in any way we can! Give us a call or book a free quote today.