Stilt Foundation

While we were awaiting move-in I had a very interesting conversation by telephone with Thurman Whisner the engineer who designed the stilt foundation of our vacation home.  He expressed conviction that the home would never flood despite its location in the floodplain, and offered the names of several local contractors who might help us, should a need arise.  (He also accurately predicted that Roy, the self-proclaimed groundskeeper, would stop by at every opportunity, which has been the case.)

It is believed that the cabin was raised to its current location in the winter of 2006-07.  Below is a transcript of Whisner's letter (dated Decemberr 2004) attached to the FEMA Flood Certificate of December 2006.

As per the request of the owner, Dee Cole, of existing 20 FT x 24 FT Cabin on Lot #25 in Cacapon River Meadows Subdivision, I, Thurman Whisner, PE/PS, completed an elevation survey to determine the actual 100-Year Base Flood Elevation with respect to the existing ground elevations near the existing Cabin location on her property and to set a Benchmark Elevation (EL 441) at top of railroad spike in an upstream forked tree.  Both the bottom main first floor and the second floor (loft area) of the existing Cabin are well below the 100 Year Base Flood Elevation (BFE) at EL454 within Flood Zone AE.

The existing Cabin on Lot #25 has had a history of damage during past major floods with deck damage and was actually washed off the foundation during the 1985 Flood.  The Cabin was reset onto a new 8”X8” treated posts (railroad ties) foundation and new decks were built after several major storms.  Thus, the existing Cabin on Lot #25 at the present elevation and on the existing foundation is likely to be inundated by any major flood along the Cacapon River, possibly causing some (future) flood damage to the Cabin.

This fact was brought more apparent to existing owner, Dee Cole, whom witnessed first hand a near miss & devastation of a major ice flow along Cacapon River this past spring.  That is the reason why the owner, Dee Cole, requested that I design a new Foundation that would withstand any major flood, especially during a spring flood with major ice flow and debris flow. 

This proposed new Foundation will be constructed along upstream side of existing Cabin and will consist of the following:

·         Steel support beam framing system at 2 FT depth bearing and

·         Anchored to six 20”diameter reinforced concrete columns at 10 FT height above

·         3 FT concrete pedestals of various heights and

·         All bearing on a reinforced concrete spread footing on 2 FT diameter X 5 FT depth concrete caissons.

·         The top W8x31# steel support beams (4 total) @ 40 FT each shall be installed under the existing 20 FT x 24 FT cabin on top of two W18X50# Lift Beans each @ 30 FT length and 2x10 treated sill plates shall be bolted to top flange of W8x31# Beams.

The cabin shall then be lifted by a 120 Ton Crane and set on top of the above proposed new Foundation with the top of steel set at the 100 Year Base Flood EL454.

Thurman W. Whisner, PE/PS

WV PE #7816 & PS #1589