This is a column by landscapers, for landscapers. In it, you’ll find knowledge, views and insights from professionals just like you, who are currently working in the industry
What are the popular types of retaining walls in your region and what are your biggest challenges when building them?
Grassroots Landscape and Construction
Interviewee: Neil Death, Director
Location: New Plymouth
Staff: 3
In New Plymouth, timber retaining walls are the most common, because they’re the most cost-effective. I’d say our biggest challenge is usually access. Nine times out of ten, someone wants a retaining wall at the back of a property, and that can be logistically challenging!
Another frequent challenge revolves around cost. Often it can cost upwards of $1,000 per metre for engineered walls, with the cost increasing with height. Every retaining wall over 1.5m high, or that is load-bearing, has to go through a consent application – so we try and keep our walls below that level and use terracing if required. However, smaller plot sizes around the city make that difficult.
A further challenge exists around property frontage. If a client needs a retaining wall at the front of their property, it often encroaches on council land, which means we’ll need to obtain a Code of Compliance Certificate, which adds to the cost and time it’ll take to complete the job.
101 Landscapes
Interviewee: Andrew Waterman, Director
Location: Auckland
Staff: 3
We probably do one retaining wall a month and access is usually the biggest challenge. Luckily, we live in the days of special diggers, which can access tight spaces. One of my diggers can get through a gate that’s only 1m wide; if they can’t, we’ll Hiab them in.
Another challenge is uncertainty about what’s in the ground. We do our best to locate any underground services using platforms like beforeUdig, a free online service, but it doesn’t know everything! We once did a job in Ponsonby, which unearthed an unexploded bomb!!
We normally build timber retaining walls but, depending on the budget, we can go for Keystone, block or plaster walls. Generally, we design retaining walls ourselves, although I work alongside landscape designers as well.
Handling consent applications adds cost to a job, so we prefer to stay away from retaining walls over 1.5m or that are load-bearing – which clients prefer as well! I find it fairly easy to stay on top of any regulation updates, so I’m confident when it comes to knowing the latest laws.
Groundcover Landscaping
Interviewee: Graeme Hopkins, Director
Location: Hamilton
Staff: 19
Retaining walls isn’t something we do a great deal of anymore and we tend to steer away from anything that requires a consent. If a client wants us to build a retaining wall that requires one, we’ll usually pass the work onto specialists. We have the machinery for walls below 1.5m high, so we will usually install the footings and get a blocklayer to lay the blocks.
That doesn’t mean we’ll never work on walls over 1.5m high. The biggest one we did was 2m high, which required an engineer’s drawing. It was on a new development, so it needed to comply with boundary legislation as well. Thankfully the consent had already been processed with the house plans.
We do a lot of timber, such as post and board or railway sleepers. If a client wants a concrete block wall, we’ll usually subcontract to a blocklayer.