This process is for commercial retaining walls or retaining wall systems providing cumulative vertical relief greater than 5' in height within a horizontal separation distance of 50' or less. These systems include but are not limited to: cast-in-place walls, soil nailing, modular retaining wall system, H-beam retaining wall system, boulder retaining walls and gabions. They shall be designed under the responsible charge of a registered design professional per the 2012 North Carolina Building Code, Section 1807.2.
Retaining wall locations are required to be identified early in the site review process and Retaining Wall (RW) package with station numbers submitted for free standing walls not part of the building structure. A site plan must be provided with the submittal of RW's to identify the locations.
Once the retaining walls have been permitted through the site review process, all subsequent building plan submittals must include a RW package marked "FOR REFERENCE ONLY" indicating that permits for the retaining walls were previously issued under separate transaction numbers. This serves as a notice to the building official that the retaining walls have already been permitted.
2012 NCBC Section 1807.2: Requires that retaining walls shall be designed in accordance with Sections 1807.2.1 through 1807.2.3:
Section 1807.2.1 General. Retaining walls shall be designed to ensure stability against overturning, sliding, excessive foundation pressure and water uplift. Where a keyway is extended below the wall base with the intent to engage passive pressure and enhance sliding stability, lateral soil pressures on both sides of the keyway shall be considered in the analysis.
Section 1807.2.2 Design lateral soil loads. Retaining walls shall be designed for the lateral soil loads set forth in Section 1610.
Section 1807.2.3 Safety Factor. Retaining walls shall be designed to resist the lateral action of soil to produce sliding and overturning with a minimum safety factor of 1.5 in each case. The load combination of Section 1605 shall not apply to this requirement. Instead, design shall be based on 0.7 times nominal earthquake loads, 1.0 times other nominal loads, and investigation with one or more of the variable loads set to zero. The safety factor against lateral sliding shall be taken as the available soil resistance at the base of the retaining wall foundation divided by the net lateral force applied to the retaining wall. Exception: Where earthquake loads are included, the minimum safety factor for retaining wall sliding and overturning shall be 1.1.
Exceptions to the process:
Retaining walls less than five (5) feet tall are not required to have a permit. However, retaining wall systems less than five (5) feet in cumulative vertical relief and adjacent to a structure located closer than the vertical relief shall be designed under the responsible charge of a registered design professional and shall require a permit and inspection.
Are there any pre-requisites to this process?
- If site fill soils are retained by the non-residential retaining wall, the permit should be obtained at the time of grading permit issuance
- If the retaining wall is located adjacent to a walking or driving surface, guards installed in accordance with the provisions of 2012 NCBC Section 1013 will be required
What do I need to submit to the City?
|RETAINING WALLS SUBMITTAL PACKAGE||Required for Submittal||
Where do I submit my application?
What are the review requirements?
- Permit address will be validated to the IRIS parcel address. When there is more than one retaining wall on the parcel, the unique identification for each wall will be defined in the IRIS authorized work.
- If the retaining wall is not attached to a new non-residential building, a next day permit will be issued with the IRIS Work Type as "Other" and the Census Code shall be "601 Miscellaneous". An engineer's certification will be required during the final inspection.
- The reviewer shall add the following comment in IRIS under the comment section of Detail Review screen, "Design details and Engineering letter certifying the retaining wall is required prior to the final inspection approval and the issuance of the Certificate of Compliance."
- Plans are routed as "Other" to: Building, CSC, Zoning, Site Accessibility, Stormwater, Transportation, Urban Forestry and Electrical, if needed.
- Permits issued: Building and Zoning only; If lights are on the wall, an electrical permit will also be required.
What inspections will be needed?
When the retaining wall construction has been completed, a final building inspection will be required. A certification letter (engineering inspection report) stating that the retaining wall has been inspected and approved by the Special Inspector must be presented to the City of Raleigh Inspector at the time of the inspection. The certification letter shall be signed, sealed, and dated by the registered design professional who has been acting as the Special Inspector. The certificate letter shall at minimum consist of the following: (1) Statement that the Special Inspector has visited the site; (2) Statement detailing the conditions the Special Inspector has observed on the site; (3) Description of permit drawings or documentation the special Inspector has reviewed in reaching her/his conclusions; (4) Statement that the foundation support system is adequate for the intended site conditions; (5) Statement pertaining to the measurement of the quality of construction materials for conformance with permit drawings and specifications; (6) Determination of similarity of actual soil conditions to those anticipated in design; (7) Statement pertaining to the examination of backfill materials and any drainage systems for compliance with permit drawings and specifications; (8) Statement of final conclusions and recommendations. A paper copy of the certification letter shall be provided to the City of Raleigh Inspector at the final inspection and it shall also be e-mailed to email@example.com with exact words in the e-mail subject line "Retaining Wall, SSI, Address, Transaction # & Permit #"
What fees are involved and when do I pay them?
Building permit will be issued at the minimum permit fee as provided in the Development Fee Schedule.