Building in a Flood Zone, Part II

So given that we're in the flood zone and knowing that our finished floor level should be above and out of the flood level, how do we get there...?

What are my options?

We were given two options on our project:

1. Using a traditional continuous foundation, build a cripple wall on top to raise the floor height and build walls on the raised floor, or...

2. Extend on up the traditional foundation so that the foundation stem walls are high enough for traditional framing to sit on these stilt-like concrete walls. 

There are a couple things to consider here. From a financial perspective, the comparison in cost of construction. The cost of concrete stem walls vs. wood cripple wall. Also keeping in mind that the cripple wall, if under the Base Flood Elevation, has to be P.T. (pressure treated) lumber. Availability and accessibility may also become financial factors. Can you pump concrete to the job site in an efficient manner? Would it be easier and faster to have framers put up a wall? Pouring concrete walls calls for blocking and formwork framing that also takes additional time. 

From a durability and building lifespan perspective, the thought of water possibly coming up onto the wood cripple wall vs. a concrete wall. Granted, the cripple wall will be P.T., but there's something inside of my that always cringes when I think of framing in standing water, let alone the ability to dry itself off after hydro contact. Some may even bring up the comparison of embodied energies. Concrete has much more embodied energy and is permanent, while as wood is much more malleable and light. 

From a visual and design perspective there may be ways to show off or hide the raised floor of a house in the flood zone. What are the design intentions of the exterior wall? Exposed concrete that shows of formwork can be very elegant if done with a high level of craftsmanship. A wood cripple wall will need to be clad with stucco, stone, or some other finish. 

Coming up in the next part of this series: flood vents.