Removing old facade paint with a pressure washer
Facade paint can often be removed with a pressure washer if the texture under the paint is intact and resistant. If there is plaster or brick under the paint, the water pressure must be used in good doses. On concrete masonry, strong pressure is usually not a problem.
High pressure is not always possible
Since a pressure washer works with high mechanical pressure, it is always necessary to check on façades whether the façade paint has a higher resistance than the substrate on which it is located. If this is the case, the paint cannot be removed without damaging the masonry or plaster.
The situation is relatively clear when concrete paint or a coating on concrete blocks is to be removed. Provided that the concrete is not damaged and, for example, has crumbled, it is possible to work with commercially available high-pressure cleaners at maximum pressure in bar.
Also of interest: How many Bar do I need for my Pressure Washer?
How much pressure can plaster and brick withstand?
Paint on a plastered façade or on brick must be applied in doses. The condition of the substrate always determines whether the cleaning method is possible. Undamaged masonry and plaster can usually withstand an impact pressure of up to 150 bar. Thermal insulation systems on the façade reduce the resistance.
A usually better alternative is a high-pressure cleaner that works with hot steam. Steam dissolves most façade paints at an impact pressure of between eighty and 120 bar. This pressure is often not sufficient to dissolve the paint purely mechanically with a conventional high-pressure cleaner. When working on a façade, always start with a low pressure (fifty bar) and gradually increase the pressure to see how it works.
Also of interest: How to Match the right Pressure Washer Nozzle
Planning and test steps
Facade paint should only be removed with a pressure washer if the following damage can be ruled out:
- Cracks and crevices can tear open further
- Crumbling dirt develops under the worked surface
- Plaster lifts off or throws up
- No cavities are visible when tapped off
