Do you need a site plan for a retaining wall permit? In many cities and counties, the answer is yes. Retaining walls can affect soil stability, drainage, neighbouring properties, underground utilities and nearby buildings, so permit reviewers often need a clear drawing showing exactly where the wall will be built.

A retaining wall permit site plan is a scaled, top-down drawing of the property. It shows the proposed wall in relation to property boundaries, the existing house, driveways, slopes, drainage, easements, utilities and other structures.

The site plan is normally submitted with wall elevations, cross sections, footing details and structural engineering when those documents are required. The site plan explains where the wall will be located; the engineering explains how the wall will safely retain the soil.

Permit thresholds differ significantly between jurisdictions. Wall height is important, but it is not the only factor. A lower wall may still require approval when it supports a driveway, building, steep slope or another surcharge load, sits near a property line, affects drainage or is located in an environmentally sensitive area. [1][2][3][4]

What Is a Retaining Wall?

A retaining wall holds back soil where the ground level is different on the two sides of the wall.

Residential retaining walls are commonly used to:

• Create a level backyard
• Support a driveway
• Protect a building pad
• Control a steep slope
• Create garden terraces
• Support patios, walkways or parking areas
• Prevent soil erosion
• Separate areas with different ground elevations

Common wall systems include:

• Concrete block retaining walls
• Poured concrete walls
• Segmental block walls
• Timber retaining walls
• Natural stone walls
• Gabion walls
• Soldier-pile walls
• Mechanically stabilised earth walls
• Rockeries

The material alone does not determine whether a permit is required. Reviewers also consider wall height, soil conditions, drainage, slope, nearby loads and the consequences if the wall moves or fails.

When Does a Retaining Wall Usually Need a Permit?

A permit is more likely to be required when the proposed wall:

• Exceeds the locally exempt height
• Supports a driveway, parking area or road
• Supports a house, garage, shed or other structure
• Supports a steep ascending slope
• Has a fence, guardrail or another wall above it
• Is part of a tiered or terraced wall system
• Will be built close to a property line
• Could affect a neighbouring structure or property
• Requires substantial excavation or fill
• Changes existing drainage patterns
• Is inside a drainage or utility easement
• Is located in a floodplain or environmentally sensitive area
• Extends into the public right-of-way
• Replaces a failed or unpermitted wall

Portland requires a building permit for retaining walls over four feet high, measured from the bottom of the footing to the top of the wall. A permit is also required for a wall affected by an adjacent slope or another surcharge, even when the wall itself is not over four feet. [1][7]

Seattle provides a permit exemption only when the wall is four feet or lower, the property is not affected by an environmentally critical area and the work will not damage adjoining properties or structures. A wall at a property line may require a permit because of the potential effect on neighbouring property. [2]

Denver requires a zoning permit for all walls, including retaining walls, over 12 inches high. Building-permit and engineering requirements increase with wall height and construction type. [3]

Fairfax County uses a different system. Its residential retaining-wall permit applies to certain simple walls retaining more than three feet but no more than four feet of earth. Walls retaining more than four feet are handled through its commercial retaining-wall permit process. [5]

How Is Retaining Wall Height Measured?

One of the most common permit mistakes is measuring only the exposed face of the wall.

Many building departments measure retaining-wall height from the bottom of the footing to the top of the wall. Part of the wall and footing may be underground, so a wall that appears to be only three feet high above grade may exceed four feet under the applicable measurement method.

Your drawings may need to identify:

• Bottom-of-footing elevation
• Bottom-of-wall elevation
• Top-of-wall elevation
• Existing grade on both sides
• Proposed finished grade on both sides
• Maximum retained-soil height
• Total structural wall height

Seattle expressly measures from the bottom of the footing, including portions below grade, to the top of the wall. Portland uses the same bottom-of-footing-to-top-of-wall measurement for its four-foot permit threshold. [2][7]

What Is a Surcharge Load?

A surcharge is an additional load placed on the soil behind or near the retaining wall.

Examples include:

• House or garage foundations
• Driveways and parked vehicles
• Swimming pools
• Sheds and accessory buildings
• Patios and decks
• Large trees
• Stockpiled soil or materials
• A steep ascending slope
• Another retaining wall

A surcharge increases the pressure acting on the wall. A relatively short wall supporting a driveway or steep slope may therefore need engineering and approval even when its height is below the normal permit threshold.

Portland identifies adjacent slopes, building footings and other surcharge loads as factors that must be evaluated during retaining-wall design and site-development review. [1][7]

When Is a Site Plan Required?

A site plan is commonly required when the building department, zoning office or site-review team needs to evaluate the wall’s location and effect on the property.

You are especially likely to need one when:

• The wall requires a building permit
• The wall requires zoning approval
• The wall is close to a property boundary
• The property is sloped
• The wall supports a building or driveway
• Cut or fill will change the ground levels
• The wall may affect stormwater drainage
• Underground services are nearby
• An easement crosses the project area
• Engineering drawings must be reviewed
• Several walls form a tiered system
• City staff must review erosion control or tree protection

Portland expressly requires a site plan, often called a plot plan, and engineering information as part of its residential retaining-wall permit process. [1]

Denver requires a site plan showing the proposed wall, lot lines, setbacks, existing structures, adjacent roads and the wall height and materials. [3]

Austin’s qualifying small-project retaining-wall process requires a construction site plan and site-development permit. Its submittal requirements can include base information, drainage, construction details and environmental information. [4]

What Should a Retaining Wall Permit Site Plan Show?

The exact checklist varies, but a complete residential retaining-wall site plan commonly includes the following information.

Property Boundaries and Lot Dimensions

Show the complete legal outline of the property.

Include:

• Front property line
• Side property lines
• Rear property line
• Length of each boundary
• Lot width and depth
• Irregular or angled boundaries
• Property address

The property lines provide the reference points for locating the wall and measuring its setbacks.

Do not assume that an existing fence, hedge or old wall marks the exact legal boundary. A boundary survey may be needed where the wall or its footing will be close to a property line.

Street, Alley and Public Right-of-Way

Show all streets and alleys adjoining the property.

Include where relevant:

• Street name
• Public alley
• Sidewalk
• Curb or road edge
• Road shoulder
• Public right-of-way
• Secondary street on a corner lot

Portland notes that work inside the public right-of-way receives separate transportation review and may need an additional permit. It also warns that the wall footing or toe should not extend beyond the property boundary. [1]

Existing House and Structures

Show existing buildings and improvements that could affect the wall.

These may include:

• House
• Garage
• Carport
• Shed
• Accessory dwelling unit
• Deck or patio
• Swimming pool
• Driveway and parking areas
• Walkways and stairs
• Existing retaining walls

Show measured distances between the proposed wall and nearby structures.

A wall located below a house, garage or driveway may be supporting a surcharge load. A wall above a building may also create drainage, stability or excavation concerns.

Proposed Retaining Wall Alignment

Clearly identify the wall using a label such as:

Proposed Retaining Wall

Show the complete wall alignment from beginning to end.

Include:

• Straight wall segments
• Curved sections
• Wall corners
• Changes in wall height
• Wall ends or returns
• Stairs built into or beside the wall

Use a bold line, hatching or another clear line style so the proposed wall can be distinguished from existing structures and contour lines.

Existing Wall to Remain or Be Removed

Where an old wall exists, clearly identify:

• Existing wall to remain
• Existing wall to be demolished
• Existing wall to be reconstructed
• Sections proposed for partial replacement
• Existing footings proposed to remain

An existing wall may not satisfy current structural, drainage or setback requirements. Rebuilding it in the same position does not automatically mean that permit approval is unnecessary.

Wall Length

Show the total wall length and the length of each separate segment.

For a wall that changes direction, dimension:

• Each straight section
• Curved sections
• Returns
• Steps in the wall
• Separate wall tiers

A useful note might read:

Proposed Segmental Retaining Wall — Total Length: 64 ft

Wall Height

Show the maximum and minimum wall heights.

The height may vary across a sloping property, so a single wall-height label may not be enough.

Identify:

• Maximum retained-soil height
• Maximum exposed-wall height
• Total height from footing to wall top
• Height at wall ends
• Height at major changes in grade

Denver asks applicants to show the proposed wall location and height on the site plan. [3]

Top-of-Wall and Bottom-of-Wall Elevations

Top and bottom elevations help reviewers understand how the wall follows the slope.

Show elevations at:

• Each end of the wall
• Wall corners
• Changes in wall height
• Steps in the wall
• High and low points
• Drainage outlets

Possible labels include:

• TW — Top of Wall
• BW — Bottom of Wall
• FG — Finished Grade
• EG — Existing Grade
• BOF — Bottom of Footing

Portland’s residential site-plan guidance specifically calls for proposed retaining walls to show top and bottom elevations. [6]

Distance to Property Lines

Show the shortest distance between the wall and each nearby property line.

Dimension:

• Wall face
• Back of wall
• Footing toe
• Footing heel
• Geogrid reinforcement where applicable
• Drainage outlet

The visible wall may be inside the property while the footing, heel or geogrid extends across the boundary. The full structural system must remain on the correct property unless legal permission has been obtained.

Footing and Wall Width

The site plan may show the general wall footprint, while the engineered plan normally provides the exact footing dimensions.

Where relevant, identify:

• Wall thickness
• Footing width
• Footing toe
• Footing heel
• Geogrid reinforcement zone
• Excavation limits

Portland cautions applicants to ensure that no part of the foundation or structural toe extends off the property. [1]

Existing and Proposed Contours

Contour lines show how the land rises and falls across the property.

The plan may need to show:

• Existing contours
• Proposed finished contours
• Contour intervals
• Direction of slope
• High and low points
• Areas where the grade will change

Portland recommends contour lines at two-foot intervals when the ground level changes substantially and asks applicants to distinguish existing from finished grade. [6]

Existing and Proposed Ground Levels

Show the ground elevation on both sides of the proposed wall.

Include:

• Existing grade behind the wall
• Existing grade in front of the wall
• Proposed retained grade
• Proposed lower grade
• Finished grade near structures
• Finished grade at wall ends

This information helps reviewers calculate the true retained height and determine whether the wall supports a slope or surcharge.

Cut and Fill Areas

Show where soil will be removed or added.

Identify:

• Area of excavation
• Maximum depth of cut
• Area of imported fill
• Maximum fill depth
• Temporary stockpile area where relevant
• Final slope above and below the wall

Austin’s small-project process limits the wall length, height, backfill and cut for projects using that particular application pathway. Its instructions also require existing and proposed grades and environmental information. [4]

Slope Above the Wall

Show the slope behind or above the retaining wall.

Include:

• Slope direction
• Slope ratio or percentage
• Distance from wall to top of slope
• Contour lines
• Buildings or driveways on the slope

An ascending slope can increase the soil pressure acting on the wall. Portland requires the lateral pressure used in the design to be increased where the wall supports an ascending slope. [7]

Slope Below the Wall

Show any descending slope below the wall.

This can affect:

• Footing stability
• Sliding resistance
• Bearing capacity
• Erosion
• Maintenance access
• Potential damage to neighbouring land

A wall near the top of a steep slope may need geotechnical analysis even when the wall itself is not especially high.

Surcharge Loads

Show nearby features that place additional loads on the retained soil.

These may include:

• House or garage
• Driveway
• Parking area
• Swimming pool
• Shed or ADU
• Deck or patio
• Another retaining wall
• Steep ascending slope

Include measured distances from the surcharge feature to the proposed wall.

Our guides on driveway permit site plans and home addition permit site plans explain related site details for walls supporting those improvements.

Tiered or Terraced Retaining Walls

Tiered walls consist of two or more retaining walls built at different elevations.

Show:

• Each wall alignment
• Height of each wall
• Horizontal distance between walls
• Top and bottom elevations
• Slope between tiers
• Drainage behind each wall
• Total combined elevation change

Two shorter walls are not always reviewed as completely independent structures. When tiers are close together, the upper wall and retained soil can create a surcharge on the lower wall.

Fairfax County limits its simpler residential retaining-wall process to walls that are not tiered, stacked or subject to surcharge loading. [5]

Drainage Behind the Wall

Water pressure is one of the most important retaining-wall design issues.

The plans may show:

• Perforated footing drain
• Drainage gravel
• Filter fabric
• Weep holes
• Drain outlet
• Connection to an approved drainage system
• Waterproofing where applicable

Portland requires walls to be designed for full hydrostatic pressure unless an appropriate drainage system is installed. Its code also requires subdrain details, discharge-line locations and the disposal method where groundwater or seepage may affect the wall. [7][8]

Surface Drainage

Show how surface water will move around the wall.

The site plan may include:

• Drainage-flow arrows
• Swales
• Catch basins
• Trench drains
• Stormwater pipes
• Roof-downspout outlets
• Driveway drainage
• Lawful discharge point

The proposed grading should not direct water toward the wall, neighbouring property or a building foundation.

Drainage Discharge Point

Identify where the retaining-wall drainage system will release water.

Possible discharge methods may include:

• Approved stormwater connection
• Daylight outlet on the property
• Drainage swale
• Infiltration facility where permitted
• Other approved disposal point

A drainage pipe that ends at the property line and sends concentrated water onto a neighbour’s land is unlikely to win friends—or permit approval.

Easements

Show every known easement affecting the proposed wall.

Common examples include:

• Utility easement
• Drainage easement
• Sewer easement
• Stormwater easement
• Access easement
• Shared-driveway easement

Label the easement width and purpose.

Do not place the wall, footing, drainage system or geogrid reinforcement inside an easement without confirming that construction is allowed and obtaining any required permission.

Underground Utilities

Show known services close to the wall and excavation area.

These may include:

• Sewer line
• Water service
• Gas line
• Electrical service
• Telecommunications line
• Stormwater pipe
• Utility meters
• Inspection openings

Austin’s retaining-wall instructions require utility location before work in city easements or street rights-of-way. [4]

Underground services should be located through the appropriate local utility-location service before excavation begins.

Overhead Utilities

Show overhead power lines and utility poles where excavation equipment, cranes or material delivery may affect them.

The plan may need to identify:

• Utility-pole location
• Overhead line route
• Required clearance
• Construction-access route

Driveways and Parking Areas

Show driveways or parking areas above, below or beside the wall.

Include:

• Driveway edge
• Distance to wall
• Vehicle parking area
• Driveway slope
• Drainage direction
• Guard or barrier where required

A driveway creates both a structural surcharge and additional stormwater runoff.

Buildings Near the Wall

Show nearby buildings and their measured distance from the wall.

The structural or geotechnical review may consider:

• House foundation
• Garage slab and footing
• ADU foundation
• Shed or accessory structure
• Deck footing
• Patio-cover posts

Portland’s site-development review specifically considers the effect of surcharge loads from new buildings and structure footings and the protection of existing buildings during construction. [1]

Swimming Pools

Show a swimming pool when it is close to the proposed wall.

The plans may need to address:

• Pool location
• Distance between pool and wall
• Pool water and soil surcharge
• Pool-deck drainage
• Pool barrier
• Construction access

A retaining wall supporting a pool area will normally need careful structural and geotechnical assessment.

Fences and Guards Above the Wall

Show fences, guardrails or privacy screens proposed above or near the retaining wall.

Identify:

• Fence or guard location
• Height
• Post spacing
• Post-foundation method
• Combined wall-and-fence height

A fence adds wind load, and fence posts should not be installed into the wall without confirming that the wall was designed for them.

Denver requests elevations when a proposal combines materials, such as a fence placed above a retaining wall. [3]

Stairs and Landings

Show stairs, landings and pathways built through or beside the wall.

Include:

• Stair width
• Direction of travel
• Top and bottom landings
• Handrails or guards
• Connection to walkways
• Drainage around the stairs

The stairs should not interfere with wall drainage or weaken the retaining system.

Wall Materials

Identify the proposed wall material or system.

Examples include:

• Segmental concrete block
• Reinforced concrete
• Concrete masonry
• Pressure-treated timber
• Natural stone
• Gabions
• Soldier piles and lagging

Denver asks applicants to identify the proposed wall materials as part of the zoning submittal. [3]

Geogrid and Reinforcement Area

Segmental retaining walls may use layers of geogrid extending into the retained soil.

The engineered plans may show:

• Geogrid length
• Number of layers
• Vertical spacing
• Reinforced-soil zone
• Required soil compaction

The site plan should provide enough room for the full reinforced-soil system to remain on the property and avoid utilities and easements.

Trees and Vegetation

Show significant trees where the wall or excavation may affect them.

Include:

• Tree-trunk location
• Tree canopy where relevant
• Trees proposed for removal
• Trees to remain
• Tree-protection area
• Roots near the wall or excavation

Charlotte’s residential-lot process may include Urban Forestry review in addition to zoning and stormwater review. [9]

Septic Systems and Private Wells

Properties without public sewer or water may need to show:

• Septic tank
• Drain field
• Reserve disposal area
• Private well
• Required separation distances

Fairfax County notes that Health Department review may form part of the retaining-wall permit process when a property uses a private well or septic system. [5]

Floodplain and Environmental Areas

Additional review may apply when the property is located in a:

• Floodplain
• Wetland area
• Landslide-prone area
• Steep-slope area
• Environmentally critical area
• Protected drainage corridor

Seattle does not allow its usual four-foot retaining-wall permit exemption on a parcel affected by an environmentally critical area. Grading or floodplain permits may also apply. [2][10]

Austin’s application instructions require applicants to identify floodplain and watershed conditions and provide applicable environmental information. [4]

Erosion and Sediment Control

Excavation and grading can release soil into streets, drainage systems and neighbouring properties.

The plans may need to show:

• Silt fence
• Construction entrance
• Inlet protection
• Soil-stockpile protection
• Limits of disturbance
• Temporary drainage measures
• Final stabilisation and planting

Portland may require an erosion, sediment and pollutant-control plan for clearing or grading work. Charlotte includes erosion-control review where applicable to the amount of land disturbance. [7][9]

Construction Access

Show how excavation equipment and wall materials will reach the project area when access is limited.

The plan may include:

• Driveway access
• Side-yard access
• Gate width
• Excavator route
• Material-storage area
• Temporary shoring area
• Protection of neighbouring property

Construction must not undermine nearby buildings, fences, sidewalks or neighbouring land.

North Arrow, Scale and Drawing Information

The site plan should include:

• North arrow
• Recognised drawing scale
• Property address
• Drawing title
• Date prepared
• Revision number

Common residential site-plan scales include:

• 1 inch = 10 feet
• 1 inch = 20 feet
• 1 inch = 40 feet for larger properties

Denver specifically requires the north arrow, adjacent streets, lot lines and existing structures on its wall site plans. Austin also includes the north arrow and project information among its construction site-plan requirements. [3][4]

Site Plan vs Retaining Wall Engineering

A site plan does not replace engineered retaining-wall drawings.

The Site Plan Shows

• Property layout
• Wall location and length
• Property-line setbacks
• Existing structures
• Top and bottom elevations
• Slopes and contours
• Drainage flow
• Easements and utilities

The Engineered Plans May Show

• Wall cross section
• Footing size and reinforcement
• Wall thickness
• Steel reinforcement
• Geogrid length and spacing
• Allowable soil bearing pressure
• Active soil pressure
• Surcharge loads
• Sliding and overturning calculations
• Drainage details
• Construction specifications

Portland requires stamped drawings and calculations from an Oregon-registered engineer for walls over four feet tall. Other jurisdictions use different engineering thresholds. [1]

Fairfax County allows its published typical details to be used for certain simple walls retaining no more than four feet of earth, but more complex walls require project-specific plans. [5]

When Might a Geotechnical Report Be Required?

A geotechnical or soils report may be required when:

• The site is steep
• The soil is expansive or unstable
• The wall is unusually high
• The wall supports a major surcharge
• The property has a history of settlement or landslide movement
• Groundwater is present
• The wall uses deep foundations or piles
• Several walls form a complex terraced system

Portland notes that soils special inspections may be required for retaining walls, steep-slope foundations, piling and landslide-remediation work. [1]

Replacing a Failed Retaining Wall

A replacement wall may need approval even when it follows the approximate location of an older wall.

The application may need to address:

• Why the original wall failed
• Existing drainage problems
• Bulging, rotation or settlement
• Changed ground levels
• New surcharge loads
• Damage to neighbouring property
• Temporary shoring during demolition

A replacement site plan should show:

• Existing wall to be removed
• Proposed replacement wall
• Changes in wall location
• Existing and proposed elevations
• New drainage system
• Structures supported by the wall

Replacing a failed wall with the same drainage and footing details is an ambitious way to schedule the next failure.

Do You Need a Survey?

Not every retaining-wall permit requires a new boundary survey. An existing property survey or recorded plat may provide a usable base.

A new or updated survey may be needed when:

• The wall is close to a property line
• Property corners cannot be located
• An old wall or fence may not follow the legal boundary
• The footing or geogrid will extend toward a neighbour
• An easement location is uncertain
• Certified elevations are required
• The property is in a floodplain
• The permitting authority specifically requests one

A drafted permit site plan is not a legal boundary survey and should not be represented as one.

See our guide on site plans versus surveys for a clearer explanation of the difference.

Can You Use an Online Map as the Site Plan?

An aerial image may help identify the general property layout, but it is rarely enough for a retaining-wall permit.

Online imagery may be:

• Outdated
• Distorted
• Missing legal boundaries
• Missing accurate ground elevations
• Missing contour lines
• Missing easements and underground utilities
• Unable to show the wall footing or drainage system

A retaining-wall site plan should use a consistent scale and include reliable written dimensions, elevations and site information.

Common Retaining Wall Site Plan Mistakes

Permit applications can be delayed when the drawing does not explain the wall or surrounding property clearly.

Common mistakes include:

• Property lines are missing
• The proposed wall is not clearly labelled
• Wall length is missing
• Only the visible wall height is shown
• Bottom-of-footing depth is ignored
• Top and bottom elevations are missing
• Wall setbacks are omitted
• The footing or geogrid crosses the property line
• Existing and proposed grades are unclear
• Contours are missing on a sloping lot
• Cut and fill areas are not shown
• A driveway or building surcharge is omitted
• Tiered walls are shown as separate unrelated walls
• Drainage behind the wall is not addressed
• The discharge point is missing
• Easements and utilities are ignored
• Existing structures are omitted
• Fences or guards above the wall are not shown
• The drawing is not to scale
• There is no north arrow
• The site plan conflicts with the engineering drawings

What Information Is Needed to Prepare the Site Plan?

Collect as much of the following information as possible:

• Property address
• Wall location
• Total wall length
• Maximum and minimum wall height
• Existing and proposed ground levels
• Top-of-wall elevations
• Bottom-of-wall or footing elevations
• Wall material or system
• Distance to property lines
• Nearby buildings and structures
• Driveway, pool or other surcharge information
• Existing and proposed contours
• Cut and fill information
• Drainage details
• Photos of the property and slope
• Rough sketch with measurements
• Existing survey or plot plan
• Recorded plat if available
• Known easements and utilities
• Engineer or manufacturer drawings
• Permit-review comments

Retaining Wall Permit Site Plan Checklist

Does a Site Plan Guarantee Retaining Wall Permit Approval?

No. A clear site plan provides the location and property information needed for review, but approval also depends on the wall design, soil conditions, drainage, zoning rules and site constraints.

The project may also require:

• Structural engineering
• Geotechnical or soils report
• Licensed boundary or topographic survey
• Zoning approval
• Grading permit
• Erosion-control plan
• Stormwater or drainage approval
• Right-of-way permit
• Floodplain or environmental review
• Tree-removal approval
• Special inspections
• HOA or architectural-review approval

Need a Site Plan for a Retaining Wall Permit?

Site Plan Pros prepares clear residential site plans for homeowners, contractors, landscapers, engineers and permit applications.

Your retaining wall site plan can show:

• Property boundaries
• Existing house and structures
• Proposed wall location and length
• Wall height and setbacks
• Top and bottom elevations
• Existing and proposed grades
• Contours, slopes, cut and fill
• Drainage flow and discharge
• Easements and utilities
• Other important property details

You may also find our guides on driveway permit site plans, home addition permit site plans, patio cover and pergola site plans and permit site plan checklists helpful.

Confirm the local height threshold, measurement method, engineering requirements, setbacks and drainage rules before excavation begins.

Sources

1. City of Portland — Residential Retaining Wall Permits
2. Seattle Department of Construction and Inspections — Retaining Walls and Rockeries
3. City and County of Denver — Fences, Walls and Retaining Wall Permit Requirements
4. City of Austin — Small Project Retaining Wall Overview and Application Instructions
5. Fairfax County — Residential Retaining Wall Permits
6. City of Portland — Drawing a Residential Site Plan
7. City of Portland — Clearing, Grading and Retaining Wall Code
8. City of Portland — Retaining Wall Drainage and Terracing Requirements
9. City of Charlotte — Individual Residential Lot Reviews
10. Seattle Department of Construction and Inspections — Grading Permits