Tiered retaining walls???

[mtCDCcb]

My condo complex is replacing an existing retaining wall. It is 11' tall. Are there any requirements that would now require this wall to be tiered? If so at what height is this required? Thanks.

[Jerry Peck - Codeman]

That would all depend on the engineer and how they designed the retaining wall.

The could design it tapered and formed and poured concrete, they could possibly have a straight (not tapered) wall with a footing and steel sufficient to transfer the loads to the footing to keep the wall from rotating, they may be able to tie the wall back with deadman anchors; or they could go with a masonry wall of greater thickness and sufficient steel in it to resist the loads.

All the above suppositions are based on the 11 foot wall being 11 feet of unbalance fill, meaning that the fill on one side of the wall is 11 feet higher than the fill on the other side of the wall.

Too many variables be anything more than general about so potential options - your engineer would be the person to provide the best answer to your question due to those variables, which could include the soil type, the angle of repose for that soil type (for example, a wall cut into rock would not require much, a wall with sand on the high side would require quite a bit more to keep the soil, sand, in place). For rock, than angle of repose may well be 90 degrees and the rock would be stable, some soils may have an angle of repose of 45 degrees, others less. Think about what happens when you make a large pile of soil and the pile spreads out on its own as the pile gets higher, that natural angle is the angle of repose - the soil will be stable at or below that angle, unstable above that angle as the soil will be trying to level itself out.