Cost & quoting
How much does a limestone retaining wall cost in Perth?
What moves the price on any given block: the length and height of the
wall, how much excavation the site needs, how easily a machine can get
in, whether the ground behind the wall carries any load such as a
driveway, and how much drainage and capping the job calls for. Two walls
the same length can price very differently if one sits on flat sand with
truck access and the other is up a steep block behind a house.
We quote on site rather than over the phone, because the fall of the
land and the access are what actually set the price, and neither shows
up in a photo.
Is the quote really free?
Yes. We'll come out, walk the block, measure up and give you a written,
itemised price. It costs you nothing, and you're not committing to
anything by having us look.
What do you need from me to quote a job?
Roughly where the wall is going and about how long and high you want it.
That's enough to book a visit. Photos help but aren't essential. If
you've got a site survey, a plan from your builder or anything from your
council, have it handy. It saves us both a step.
Council approval & engineering
Do I need council approval for a retaining wall in WA?
Usually yes, once the wall retains more than about 500mm
of ground. That measurement is the retained height (ground level on the
low side up to the top of the retained face), not the total height of
the blocks. Below that, many Perth councils don't require approval for a
straightforward garden wall.
Three things override the height rule and commonly trigger approval at
any height: the wall sits on or near a property boundary, something
loads the ground behind it such as a driveway or parking, or the
property sits in a heritage or special control area.
Requirements differ between Perth councils, so treat
the above as the general shape rather than the rule for your block. We
check what your council asks for as part of quoting, and we'll tell you
plainly if a job needs approval before we can start.
Does a retaining wall need an engineer?
Structural engineering is generally required once a wall goes over
1 metre high, and for any wall carrying a driveway or
vehicle load at any height, under the Australian standard for retaining
walls (AS 4678). Walls in the 500mm to 1 metre range often need
engineering alongside the council approval.
What if the wall is on the boundary with my neighbour?
Boundary walls need more care than walls sitting inside your own block.
Many Perth councils require a building permit for a retaining wall on a
boundary regardless of its height, and where the wall affects the ground
level on both sides your neighbour generally needs to be consulted.
It's worth having the conversation with them early. A wall that fixes a
shared drainage or level problem is usually an easy discussion; one that
arrives unannounced is not.
The wall itself
How long does a limestone retaining wall last?
Decades, when the base is done properly. Limestone is the stone Perth
was built on. It suits our sand, it copes with our summers, and it
weathers to a softer colour rather than degrading. What shortens a
wall's life is almost never the stone. It's an inadequate footing,
ground that wasn't compacted, or drainage that was skipped, all of which
sit out of sight until the wall starts leaning.
Limestone or concrete block: which should I use?
Limestone is the better choice when you want the wall to look like it
belongs. It's a natural stone with visible texture and it softens as it
ages, which suits bush blocks, older homes and garden settings.
Concrete block is worth considering where the wall is purely structural
and will be hidden, where the engineering demands are unusually high, or
where you want a uniform machine-made face. For most residential
retaining across Perth, limestone does the job and looks better doing it.
How big are the limestone blocks you use?
We build with large blocks: roughly a metre long, about 350mm high on
the face and around 85kg each. They're far too heavy to lift by hand, so
we place them with an excavator. That weight is a big part of why a
limestone wall sits so solidly once it's down.
Do you do the excavation as well as build the wall?
Yes. We dig out, set the levels, compact the base and lay the footing
ourselves, so you're dealing with one crew rather than a wall builder
plus a separate earthmoving contractor.
Do limestone retaining walls need drainage?
Yes, and it's the part most often skimped on. Limestone blocks and
mortar don't let water through on their own, so if rain soaks into the
ground behind a wall and has nowhere to go, it builds up pressure the
wall was never meant to hold. That pressure is what cracks and pushes
walls out of line.
So on every wall we build, we backfill behind the blocks with
free-draining gravel rather than packing soil straight against them, and
we put weep holes through the wall so the water that collects in that
gravel has a way out. Water drains away instead of pushing on the wall.
Do limestone retaining walls crack?
A well-built one shouldn't. When a limestone retaining wall cracks or
leans, the stone is rarely the problem. It's almost always water trapped
behind the wall, or a base that wasn't dug out and compacted properly,
both of which are hidden once the wall is up.
That's why we don't treat drainage as an add-on. Free-draining gravel
behind the blocks and weep holes through the face are standard on every
wall, along with a properly compacted base. It's not a different
material that stops a wall cracking; it's building the one you've got
properly.
Does a limestone wall need sealing or maintenance?
Not routinely. Limestone is left to weather in most residential jobs and
looks better for it. Sealing is an option if you want to slow the
colour change or reduce marking in a high-traffic spot, but it is a
preference rather than a requirement, and an unsealed wall is not a
neglected one.
Can you build on a steep or difficult block?
Yes. Steep and awkward blocks are a good part of what we do, and the
Perth Hills throws up plenty of them. Slope, limited access and soil
that moves all change how a wall has to be built, and they're exactly
the conditions where the footing and the drainage matter most. We'd
rather look at a difficult site and tell you honestly what it needs than
price it blind.
