Saturday, August 11, 2012

Building the Wall–The Start

Introduction
Since we bought our home in 1999, we had planned for a Level Entry.  From the street in front of our house to the front door there are twenty-two steps.  Front Windows 29_26For the able bodied, that is not much effort, but as one edges into a life less firm and a bit more unstable, those steps become a difficult prospect on a regular basis.  We have friends that use walkers, canes, and  wheel-chairs, and there may be a day where one of us may need to enter the house in an easier manner.  Large Trellis Construction 236F
As you can see from these earlier photos of the front and back yard, the hillside provides both a challenge and an excellent level access, with a bit of labor, of course.
So in the July, the project got started.  I decided to add a deck from the back door to the edge of the lot, and then a sloping walkway to the street.  (There have been numerous changes to the property since these photos were taken)
Foundation
Model
I modeled the project’s main features in Sketch-Up, in that I am not very proficient at using, there are some modeling errors, but this did provide me with basic form and strength requirements I needed for a wall that wouldn’t ever move.
At the very bottom I put in a cleat.  This is a safety feature to keep the wall from sliding on the ground.  The cleat was then keyed to the first layer of the foundation, then the next layer of the foundation was keyed to the first (not shown) and the wall is keyed to the foundation.  Rebar runs vertically and horizontally throughout all of these.  In the background of this graphic, are the supports for the ramped walkway and the much smaller walls, seating areas, etc.   Not all of this is as clear as one would hope, but I hope as this story continues, you will see all the work that was accomplished. 
Excavate a cubic yard or more of clay hillside with a mallax and shovelCleat poured 6"x6" with key to assist the footing from any slippageAce Helper: William, learning to trowel concrete.Second upper footing for wall - total thickness of footing = 16"
Wall Design
The wall is separate 8 foot sections between large heavy posts, two feet square.  The actual wall is less than 7 feet long in each section.  The walls of each post is canted to be wider in the front, and keyed to lock them together with the natural expansion and contraction the climate enforces.  The entire idea is to keep the wall in place during any combination of events: earthquakes, rains, or extreme heat. 
Several years ago we were at a museum that had a wall that had beenThis is the wall of the retaining system. It is 4" thick at the top, and 8" thick at the bottom. Rebar is heavily used to the foundation and to the pedestals. In this section it will be 36" tall. The wall will drop six inches at each 8' pedestal, until it is down to ~18 inches tall. Then benches and tree pots will be formed into each section. make to look old, rough cut lumber was used and shimmed to show the deviations in the wall contour and leave the imprint of the wood.  I used this in the garden walls, so I again used it on these walls. 
Relief of wood showing in concreteWhen forming, the wall is shimmed out with small wood pieces to make the result look rustic.  The rough hewn face of the lumber faces the concrete.  So that when it is removed, the grain of the wood shows in relief on the concrete. 

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