One of the ways communities are using arts and creativity to revitalize buildings and downtown districts are murals on buildings. However, not all surfaces are suited for murals. The best intentions of contributing to a more attractive, welcoming streetscape may result in the building owner regretting their decision.
The Historic Preservation Commission for Loveland, CO has created a webpage and downloadable publication warning about the damage and potential structural issues that may result in painting the old brick of historic buildings.
Many of the issues painting brick structures creates are related to trapping moisture in what is normally a relatively porous, breathable material. Temperature changes causing expansion of that moisture can undermine the structural integrity of the brick and mortar. The paint can obscure the development of these issues until the damage becomes severe and repairs more costly and extensive.
The other thing they note is that murals may end up hiding or muting distinctive architectural features that might be better amplified in order to celebrate the rare character of the structure and community.
There are some types of brick that are suitable for painting. Even some historic brick was intended to be painted, but only with substances which allowed them to breathe:
Some brick buildings were intended to be painted. In the United States, brick buildings constructed before the 1870s were made of a much softer, more porous type of material that needed to be protected from the elements by paint. The paints used on these buildings were natural, mineral-based paints, such as limewash or milk paint, which were breathable.
https://www.lovgov.org/services/development-services/painting-old-brick
The wise approach is to do a little research and testing to determine what the appropriate materials and approach are for a specific building. There are options for different aluminum, plywood, and engineered fabrics upon which murals can be painted and attached to buildings. The webpage and publication provide some advice about how to anchor the panels (into the mortar rather than brick) and fabric (breathable acrylic gel). Certainly there are likely other products and approaches one might utilize.
Keep in mind that geographic location should also be factored in to the materials and process chosen. The guide linked to here is calibrated to the conditions of cold, snowy winters and glaring summer sun at elevations exceeding one mile. Murals will weather differently in the relatively warmer, more humid climes of the southeast and drier, hotter deserts of the southwest, as well as the mix of annual weather conditions across the rest of the US.
