Retaining walls are common across the Fraser Valley's hillside neighbourhoods, from Promontory in Chilliwack to Eagle Mountain in Abbotsford and Cedar Valley in Mission. Before you build, it's worth knowing when a wall needs more than a good crew.
Important: rules differ between municipalities and change over time. Treat this as a guide to the right questions, and confirm the details with your city or district before you start.
When a wall usually needs engineering or a permit
Many BC municipalities require an engineer's design, a permit, or both when a wall:
- Is taller than a set height. Around 1.2 m (about 4 ft) is a common threshold, measured from the base to the top of the retained soil
- Holds up a driveway, building, parking area or other load near the top
- Sits close to a property line, a slope above or below, or a watercourse
- Is one of several terraced walls close enough to act like one tall wall
Smaller garden and bed walls usually don't need a permit, but they still need a proper base and drainage to last.
Why the rules exist
A retaining wall holds back a surprising weight of soil, and in our climate it also holds back water. When drainage behind a wall fails, winter rain builds pressure until the wall bulges, leans or collapses. Engineering makes sure taller walls are designed for the soil, height and loads they'll actually carry.
Questions to ask your city
- At what height does a retaining wall need a permit or engineering?
- Are there setbacks from property lines or slopes?
- Can the drain water from behind the wall go to the storm system?
- Are there extra rules near streams, ditches or floodplain areas?
Questions to ask your landscaper
- Have you built walls of this height before, and can I see some?
- Will the wall need engineering, and do you work with an engineer?
- How deep is the base and what's it made of?
- What drainage goes behind the wall, and where does that water go?
- Will you use geogrid to reinforce the soil behind it?
- What warranty do you offer?
Alternatives to one tall wall
If a single tall wall would need engineering, terracing with two or three shorter walls can sometimes work, as long as they're spaced far enough apart. A sloped planting bed with tough ground covers can also hold a gentle slope without any wall at all.
Ready to price it? Compare quotes from local retaining wall builders in Chilliwack, Abbotsford and Mission.