Concrete Walls

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McLaren Masonry are experts at constructing both free-standing and retaining walls out of poured in place (PIP) concrete and concrete block (CMU).

Poured in Place Concrete Walls vs CMU Walls

Poured in place (PIP) walls have several distinct advantages over CMU walls.

1. With a PIP wall, the wall thickness is 100% structural concrete.  CMU is simply a shell filled generally with a fine grout containing no aggregate.  For example: 8-inch CMU has a maximum 5-inch solid center.  12-inch CMU has a maximum 8-inch solid center.

2. With a PIP wall the structural reinforcement (rebar) is tied in place and visible for inspection prior to pouring.  A CMU wall has horizontal rebar that is laid in channels called knockout courses.  These reinforcements can be shifted during the grouting process.  Horizontal steel is cut to length and dropped into cells prior to pouring.  Is it in the center of the wall?  Or is it at the edge of the block?  That depends greatly on the workman placing it.  Unfortunately, there is no way to tell after grouting is complete.

3. PIP walls reveal any voids, honeycombs or pock holes when forms are removed.  They can be patched, sealed and remedied.  CMU walls can have voids that cannot be detected until there is a problem.

A block wall (CMU wall) can be beautiful as well as functional. Have a look at the slideshow above.

Retaining Wall Considerations

The most often overlooked cost in a retaining wall is the backfill, drain lines and waterproofing.

A well thought-out drainage system can add decades to the life of a retaining wall. Most drainage details that accompany blueprints today are boilerplate reproductions from a book. Oftentimes what is drawn simply wonʼt work. The most common detail involves a four inch diameter perforated encased in one foot of drain rock wrapped in a geo-tech fabric.

Unfortunately for this drain to work, the rock bed must be full for the pipe to work. On a 70 foot wall that would be 70 cubic feet of water before we could get water flow. 70 cubic feet of water equals 523 gallons of water. That is literally 2 tons of water pressure. Concrete by nature is porous, so that water is prematurely adding to the rusting of your structural steel. This is why waterproofing your sub-grade concrete and masonry walls is a good idea.