PPP Notes - Retaining Walls

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.