Chilliwack Mountain: A 60 Foot Rock Wall and the Yard Above It
This is the largest retaining wall we have built. Sixty feet tall, two hundred and fifty feet long, in multiple levels, holding back a Chilliwack Mountain hillside so the property above it could be used.
What Was There Before
An old house from the 1960s sitting on a sloped lot, grass running down the hill and trees across the bank. The usable part of the property was a fraction of what the owners were paying for. They decided to start over: demolish the house, rebuild, and turn the slope into something they could actually walk out onto.
That made the retaining wall the first real decision on the project. Nothing above it could be planned until the ground below it was held.
The Wall
- 60 feet tall, 250 feet long, built in multiple levels up the slope.
- 2,000 to 2,500 tons of rock, supplied by Armstrong Sand and Gravel Ltd out of Agassiz.
- Between $350,000 and $400,000 in stone alone, before any of the excavation or machine time.
- Dug ten feet into the ground so the structure is anchored into undisturbed material rather than sitting on the slope.
- Two feet of gravel under the base for drainage and to stop uneven settlement.
- Three inch clear crushed rock behind the face, giving water a path out instead of letting pressure build behind the wall.
- Geogrid through the backfill, tying the wall and the soil behind it together as one mass.
- Engineered and permitted. At this height there is no version of this job that skips either.
What Is on the Terrace Now
The wall created a level bench where there had been a bank. On it there is now a sauna, a covered roof structure, an outdoor kitchen and a fire pit. The kitchen alone came to $45,000. All of it was built by our own crew, which is the part we are proudest of. The same people who dug the hill built what sits on top of it.
The Whole Project
The wall was one part of a full property rebuild that ran about three years and came to somewhere between $2.5 and $3 million. Alongside the wall there was the demolition, the new house, a septic field, a pool and the finished yard. Two to three of our people were on site continuously through it.
The Hard Part
Not the rock. The planning. A job this size over this long changes while you are building it, and the owners refined what they wanted as the property took shape. The bigger challenge was underground. What was actually beneath the surface around the existing services did not always match what the plans said, and the work had to adjust to the ground as it was found rather than as it was drawn.
That is worth knowing if you are planning something large. The contractor who tells you nothing will change on a three year build is guessing.
Why It Matters for a Smaller Job
Most of the walls we build are nothing like this one. A typical wall runs 40 to 70 feet, stays under four feet tall where we can keep it there, and takes between a week and a month.
What carries over is the method. Compacted base, clear rock behind the face, geogrid where the height calls for it, and somewhere for water to go. A $30,000 wall in a back yard gets built the same way as a 60 foot one, just smaller.
Talk to Us About Your Slope
Call (604) 703-8315 or send a photo of the hill you are trying to hold. Site visits and written prices are free, and we are usually out within the week.