SITE DEVELOPMENT
RETAINING WALLS
- Retaining walls are designed and constructed to resist the thrust of the soil, which can cause the wall to fail by overturning, sliding or setting.
- In stone walls, resistance to soil thrust can be helped by battering the stonework (i.e. recessing or sloping the masonry back in successive courses).
- Garden-type retaining walls, usually no higher than 4 ft., are generally made from small building units of stone, masonry, or wood.
- For higher walls, reinforced concrete is more commonly used.
- Terracing may be built with walls of wood, stone, brick, or concrete.
- Walls less than 2 ft. high do not require drains or weepholes.
- Preservative-treated wood is recommended for any design in which wood comes in contact with the ground.
- Redwood may be substituted if desired.
- Stagger vertical joints from course to course 6 in. minimum horizontally. The thickness of the wall at any point should not be less than half the distance from that point to the top of the wall.
CAST-IN-PLACE CONCRETE RETAINING WALLS
- When designing cast-in-place concrete retaining walls, keep these guidelines in mind:
- Provide control and/or construction joints in concrete retaining walls approximately every 25 ft. Every fourth control and/or construction joint should be an expansion joint. Coated dowels should be used if average wall height on either side of a joint is different.
- Consult with a structural engineer for final design of all concrete retaining walls.
- Concrete keys may be required below retaining wall footing to prevent sliding in high walls and those built on moist clay.
