As time passes and a building ages, it can become weathered in both its appearance and function. Though some level of weathering is inevitable for every building, taking steps to prevent weather from damaging a building will pay off immensely. Weathering prevention varies depending on the material with which the building has been built. Furthermore, some building materials simply age and stand up to harsh weather conditions better than others. It is important to understand the nature of the material you're working with when attempting to protect it.
Paint the exterior of the building with acrylic latex paint, which protects the siding much better than oil-based paints. Once the paint begins to wear down, the building should be repainted. Depending on the weather conditions in the building's location, this should be done every five to seven years.
Apply a stone-sealer to buildings with a stone exterior. Stone, some types more than others, can be very porous and therefore vulnerable to moisture. Stone-sealants help protect stone from unwanted moisture than can lead to cracks and mold.
Fill in any gaps or cracks in the building with caulk to prevent air leaks that can lead to unwanted moisture entering into the building. This will help prevent wood siding from rotting, mold from entering into the building's interior and cracks from forming.
Clean the building's siding periodically, or when mold, algae, moss or lichen begins to appear on it. Use a power washer to remove the unwanted growth by using a power washer or by using a garden pump sprayer filled with a chlorine solution made up of one part liquid bleach to equal part water. Rinse the chlorine off with a garden hose that has a pressure nozzle.