Using a brick wall contractor or masonry contractor is important whenever you are dealing with the installation of brick, stone, or block walls. In most jurisdictions it is not possible to work as a masonry contractor without first having a great deal of hands-on training and experience, and dealing with masonry materials is not at all like dealing with other types of construction materials.
A brick wall contractor will understand, for example, that before installing any brick or stone the wall has to be properly secured with a footer or foundation that meets city or county code requirements. If the wall is a supporting wall, for instance, it needs additional stability and strength. But if the wall happens to be a stone, brick, or block installation that is exposed to intense heat -- like in a chimney, fire pit, outdoor kitchen, or BBQ set-up -- then the masonry contractors has other important considerations as well. They may have to use specially formulated mortar or special fire bricks that are designed to withstand high temperatures -- otherwise ordinary materials can actually explode, sending rubble in all directions.
Or you may need a brick wall contractor to help install a retaining wall to keep part of your landscape from eroding or collapsing. In that case the masonry contractor has to evaluate the slope and drainage of the whole project, and build the wall in such a way that it leans into and not away from the land pushing against it. Otherwise the wall will collapse over time, and many walls made by those who are not experienced masonry contractors do just that.
Stone masonry has its own unique challenges. Some types of stone when mounted on a vertical surface like a wall veneer, for instance, will sheer off and fall -- and they can hit people or damage your floors and furniture if they are inside a room. Always rely on a masonry contractor for stone work, in other words, because it is a special type of job that requires special expertise.
Any time you deal with a masonry wall installation you also deal with moisture and drainage issues, too, so this is yet another important reason to hire and rely upon a certified masonry or brick wall contractor. They can help you prevent flooding, wood rot, moisture induced mold, and other issues.