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The piers and stem walls are the legs of the house.  They support the weight of the building, and lift it off the ground which is essential and required to avoid flooding.  Its also helpful in preventing formosan termites (which live underground) from easily and inconspicuously accessing the delicious framing.  In my case, being within an historic neighborhood, I am allowed to forgo the advisory base flood elevation  (ABFE)  requirement which is a FEMA determined elevation.  Essentially, all wood elements of the house, including the sills, would need to be above the ABFE.  Therefore, the top of the piers is where one aligns their minimum elevation to.   The default minimum throughout New Orleans 3′ above the nearest adjacent grade.  In historic districts (local or federal) 18″ is the minimum.  However, one also has to build above the base flood elevation (BFE).  This is different from the ABFE.  In my case the BFE is 4.5′ NAVD (a number also determined by FEMA).  NAVD is a national datum elevation.  When I acquired my survey it was clear that my site was approximately 3′ NAVD.  So, I essentially was required to build my piers 1.5′ higher to be at 4.5′ NAVD.  Rather than building higher which might be advisable, I built at this minimum so that my finished floor height would be similar to the neighboring houses and allow the design to blend with the context.

The block masons lay the blocks in alignment with the strings provided by my contractor.  They attach the blocks first with a mortar only at the edges.  Then once all the blocks are stacked and in place, they fill all the block cavities with a pea gravel and mortar medium.  At this point my contractor should’ve bent the threaded rods so that they would land in the correct spot to receive the wood sills, however, they neglected to do so leaving the rods sticking up in random locations.  The fix will be to use 4×8 (laid with the 8″ dimension flat) sills rather than 4×6 sills so that there is more tolerance for the rod locations.  For this reasons, as aforementioned, a j-bolt anchor may be less problematic than the threaded rod anchors.

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