The following information must be submitted when applying for a permit to construct a retaining wall. Since every project is unique, there may be some situations where you will be asked to provide additional information.
- Completed building permit application
- An engineer registered in the State of Oregon provides stamped drawings and calculations for wall(s) over four feet tall
Site Plan (Scale site plans to most appropriate scale, e.g. 1”=10’ or 1/4”=1’)
- Property lines, with dimensions
- Adjacent streets and any easements
- Property address and R number
- North arrow
- Distance between buildings and between buildings and property lines
- Dimensions and area (in square feet) of any proposed paving. (If your project will add more than 500 square feet of impervious area you will need to provide a mitigation form and/or a stormwater plan)
- Dimensions and placement of the new retaining wall on the lot
To submit for a permit, bring the completed building permit application and four (4) copies of site, architectural and structural plans (for the area of proposed work and areas affected by such work ) along with intake fees to the Development Services Center.
THINGS TO CONSIDER:
(1) Engineering Evaluations
Design of retaining walls over four feet tall shall include a site sketch consistent with the site plan submitted with the application. In lieu of a site sketch in the calculation package, the engineer may submit a letter stating that the calculations were prepared for the site as shown on the submitted site plan prepared by others.
Where the retaining wall influences the loads on a building, the engineering evaluation shall also address the effect of the loads imposed onto the building. In all cases, and especially where tiered retaining walls are proposed, the analysis shall include complete free-body diagrams of the retaining walls showing all loads acting on the retaining wall system and all loads used to resist the applied forces. The calculations shall clearly state all assumptions and list the soil design parameters used in the design.
(2) Site Development and Environmental Soils
Depending upon the placement of the building or structure, the following items must be addressed in evaluation and analysis of the design:
- Slope and retaining wall drainage
- Erosion control
- Potential for shallow failures
- Potential soil creep
- Potential settlement
- Effect of surcharge loads such as new building and/or structure footings
- Protection of adjacent property and existing building during construction
(3) Right-of-Way Requirements
If your project requires construction in the public right-of-way, the Portland Department of Transportation will review the project, and issue a separate transportation permit for this work as well. For more information about right-of-way requirements, contact the Portland Department of Transportation at (503) 823-7002.
Make sure that the design of your retaining wall does not result in a section of the foundation or specifically the “toe” (the outside points of each leg of a structural angle) needing to be placed off of your property.
(4) Special Inspections
Soils special inspections and/or structural special inspections may be required prior or during the construction of your retaining wall.
Soils special inspections may be required for work that includes foundation work of a more complicated nature such as piling, or foundations on steep slopes or large jobs; and retaining walls, landslide slope remediation work or other earthwork-related work. Soils special inspection is performed by the geotechnical engineer of record and/or an approved testing agency and is hired for this purpose by the (permit holder) property owner. View more information on special inspections.