Direct answer
What should you know first?
Brick and sound concrete block can often be cleaned with controlled pressure, while EIFS, stucco, siding, painted surfaces, and many metal systems usually need lower pressure and careful solution use. Condition matters as much as material: loose mortar, failed caulk, oxidation, and open seams should be identified before washing.
Brick and concrete block
Masonry is durable, but mortar joints and surface condition determine the safe approach. Older or deteriorated mortar needs lower pressure. Efflorescence, paint, rust, and organic growth are different problems and should not be promised the same result from general washing.
Metal panels and painted walls
Pre-finished metal can chalk, streak, and collect traffic film. Water should not be driven into panel laps, trim, vents, or penetrations. Painted walls also need a test area because weak or oxidized coatings may release during cleaning.
EIFS, stucco, and siding
These materials are commonly soft washed. Low pressure reduces the chance of forcing water behind seams or damaging the face. Loose sections, failed sealant, and openings around fixtures should be noted before work begins.
Glass, signs, and transitions
Windows, awnings, signs, lighting, and material transitions are part of the elevation. They influence how the building is protected and the order in which it is cleaned. Exterior glass is normally completed last.