|Vertical walls and surfaces of retaining walls, raised planters and landscape walls,should be smooth, finished, and regular in unit composition similar to that of façade walls.
Masonry units should have a smooth finish, such as brick veneer, concrete brick, and cultured stone products. Poured in place concrete walls often achieve a finished, high quality look that is acceptable. Jointing lines and forming patterns should be incorporated into the design to give the wall a more human scale.
A smooth finish does not necessarily mean flat. Cut and chiseled block and stone can have a varied surface without having a rough texture. Examples may include quaried stone or “rennaisance stone” products. Commercial sites should generally be the smoothest, where small scale residential walls might be more textured, generally due to more generous landscape planting areas surrounding them.
While dry-stack block that is commonly used today may be considered, only the smoothest, most finished quality varieties should be used. Dry-stack, if obscured by plantings, or not visible from the street, may be acceptable.
“Finished” means surfaces intended for facades, not block intended for utilitarian conditions. While concrete masonry units with well tooled joints may be acceptable in certain designs, they typically are reserved for side and rear wall, interior utility applications, and as substrate to finished masonry.
Concrete brick products may be acceptable, depending on the unit size, coloration and finish quality. Other concrete block products with finished quality surfaces, such as burnished may block, may be considered.
“Regular” generally means the pattern in which block or stone is laid. While the common running bond is most often used today, this does not exclude other traditional bonds. When considering stone, joints should be regular in nature as opposed to random and rough. Tightly fit ashlar stone is a good example, where commonly used “ledge-stone” is not.
Scale of the bricks, stone or masonry units should be proportionate to the scale of the wall or surface. Landscape walls and especially landscape piers should be composed of smaller brick veneer scaled units.
The top of walls should be smooth, finished and regular as well. On concrete walls, this is easily achieved through the overall design details. On stone, brick and block walls, a cap should generally finish the wall. The cap could be a poured and formed concrete piece or may be precast units.
Other materials such as railroad ties should not be used on retaining walls and raised planters, especially for commercial building applications and along commercial streets. While creatively designed wood or metal walls may be considered and allowed, they would need to be well designed, have a finished quality, be durable and be carefully detailed.
Material choices for retaining walls follow similar principles to façade walls. Where buildings on the site have a masonry façade, similar materials on retaining wall should be considered. Masonry piers that are intergral to fencing should follow similar design consideration as with landscape walls.