A building permit and engineered design is required for a retaining wall when the wall is over 4 feet in height measured from the top of the wall to the bottom of the footing or if supporting a surcharge. (See illustrations below to determine if a surcharge is present) Terraced or tiered retaining walls require a building permit and engineered design if the walls are over 4 feet in height or spaced apart at a distance less than two times the height of the lower wall. The following is required for submitting a retaining wall permit:
During construction of the wall(s), it is the responsibility of the permit holder to have the engineer of record perform an inspection(s) to ensure the construction is in compliance with their design and the approved plans. Upon completion of the retaining wall, copies of the Engineer’s inspection report or observation letter shall be submitted to the Douglas County Building Department to finalize and close out the building permit.
A surcharge for a retaining wall is a load applied to the ground near the wall that results in additional lateral force on the wall. Surcharges can come from various sources, including but not limited to:
As a general guideline, any surcharge object should be positioned at least twice the total height
of the retaining wall away from its nearest point. For example, if the wall’s total height
(including both buried and exposed portions) is 4 feet, the edge of the surcharge should be placed
no less than 8 feet away from walls nearest point.
A terraced/ tiered wall consists of two or more shorter walls used in place of a single taller wall. The upper wall places additional pressure (surcharge) on the lower wall, so they are typically considered one wall unless the upper wall is set back at least twice the height of the lower wall. Additionally, the upper wall must be shorter than the lower wall.
For example, if you have two 4-foot-tall, tiered retaining walls spaced 4 feet apart, they will be considered a single 8-foot wall, which will require both a permit and engineering approval. However, if the two 4-foot walls are spaced at least 8 feet apart, they can be treated as separate walls. It’s important to note that you cannot have more than one terrace on a non-engineered wall.
• Retaining walls cannot be constructed over or on property lines unless an easement agreement is executed and reviewed by zoning.
• Retaining walls cannot encroach into any easements unless an agreement is executed with all involved agencies of interest and reviewed by zoning.
