Preventing Biological Growth on Building Exteriors in Utah

Biological growth — algae, mold, mildew, and lichen — is one of the most common exterior building maintenance challenges in Utah. While professional soft washing removes biological growth effectively, understanding what promotes growth and how to slow it between cleanings reduces maintenance costs and extends the time between professional cleaning visits.

Moisture is the primary driver of biological growth on building exteriors. Surfaces that stay moist — north-facing walls, shaded areas, surfaces near irrigation systems, and areas with poor drainage — develop biological growth faster than dry, sun-exposed surfaces.

Organic material provides nutrients for biological growth. Dust, pollen, and organic debris that accumulate on building surfaces feed algae and mold. Buildings in areas with significant tree canopy or near agricultural land accumulate organic material faster.

Surface texture affects biological growth rates. Rough, porous surfaces provide more surface area and moisture retention than smooth surfaces — and develop biological growth faster.

Improving drainage around building foundations reduces moisture accumulation on lower facade surfaces. Grading soil away from the building and ensuring downspouts discharge away from the building reduces the moisture that promotes biological growth.

Trimming trees and shrubs away from building surfaces reduces shade and organic debris accumulation — two of the primary drivers of biological growth.

Professional soft washing with biocide treatment kills biological growth at the root and leaves a residual biocide treatment on the surface that slows regrowth. The residual treatment effect is one of the key advantages of professional soft washing over pressure washing alone.