A. Retaining Wall General Regulations.
1. Retaining walls must be designed and located per the adopted IBC and IRC design standards. See Figure 18.21.025(A).
2. Notwithstanding any other provisions regarding retaining wall height, the height of any portion of a retaining wall may not reduce sight distance established by the Engineering Design Standards for vehicular and nonmotorized facilities.
3. Any grading work shall be in compliance with Chapter 15.74 ACC.
4. All portions of retaining walls, including subsurface elements such as footings, anchors, and cantilevers, shall not encroach or be located within the right-of-way or public utility easements unless explicitly permitted by the city engineer and/or by the easement language.
5. The requirements of this chapter do not apply to retaining walls in rights-of-way.
6. Additional requirements apply to retaining walls that provide support to rights-of-way as specified in the Engineering Design Standards.
7. Retaining walls designed as part of an approved preliminary plat, and located prior to recordation of the final plat, are not subject to the setback area requirements contained in this section.
B. Residential Lots.
1. Retaining walls are not permitted in the required setback areas, unless meeting one of the following criteria. The height of a wall shall be measured from the bottom of a footing to the top of the wall.
a. Retaining walls that are under 48 inches and constructed in accordance with the IRC, whether supporting a surcharge or not, are allowed in all setback areas, as regulated per each zone.
b. Retaining walls over 48 and under 84 inches and constructed in accordance with the IRC, whether supporting a surcharge or not, are allowed in all setback areas except the front and street-side setback, as regulated per each zone.
c. Retaining walls over 84 inches, constructed in accordance with the IRC, whether supporting a surcharge or not, are not allowed in the setback areas, as regulated per each zone.
2. Retaining walls visible from the right-of-way or adjacent property must be composed of rock, textured or patterned concrete, masonry, composite, or other products that complement the existing residential or neighborhood character. Products such as “ecology blocks” or plain smooth concrete are not permitted. Materials other than those listed may be used with approval from the planning director or designee.
C. Nonresidential Lots/Tracts.
1. Retaining walls visible from the right-of-way or adjacent property shall be composed of rock, textured or patterned colored concrete, masonry, or composite. Products such as “ecology blocks” are not permitted. Materials other than those listed may be used with approval from the planning director or designee.
2. For retaining walls over 48 inches in height or supporting a surcharge, the area between the right-of-way and the retaining wall shall be landscaped and maintained per Chapter 18.50 ACC.
3. Terraces created between retaining walls shall be permanently landscaped and revegetated pursuant to a mitigation or landscape plan developed by a qualified professional.
4. Notwithstanding the requirements contained in this section, retaining walls may still require a building permit if trees or other landscape features will potentially impact (e.g., tree roots) or impose a surcharge on the wall.
5. The width of the retaining wall or walls support shall not be included in any landscaping calculations or measurements.