Retaining Walls in Unanderra and Wall Replacement
Unanderra sits at the foot of the escarpment where the land flattens out towards the lake, and the ground here is clay. The suburb filled in through the post-war years with fibro and brick cottages and then sixties and seventies brick veneer, most of it on blocks that fall gently away from the hill behind them. A lot of those yards were terraced at some point in the seventies or eighties, and those walls are now at the end of their lives.
So most of the retaining work here is replacement rather than new build. Timber sleeper walls that have rotted at the posts below ground. Besser block walls bulging in the middle because there were never any weep holes or a drainage line behind them. Levels that were changed once and never properly finished. All of it failing for the same reason, which is water that had nowhere to go in soil that will not let it through.
Marcio is Wollongong based and Unanderra is a few minutes away. Retaining walls, the drainage behind them, fencing, steps and the landscaping on top are all our own work, which matters on a replacement because the drainage is the part that decides whether the new wall outlasts the old one.
Retaining Wall Work We Do in Unanderra
Drainage Built for Unanderra Clay
Free draining backfill, an aggie line with a real outlet, and geotextile so the clay does not clog it. On this ground that is the wall, not an accessory to it. Leave out any one of the three and the wall ends up holding water as well as soil, which is a load it was never designed for and the reason most of the walls we replace here failed early.
Replacing Failed Sleeper Walls
Rot starts at the back face where clay holds the moisture, so the wall looks sound from the front until a section lets go. We will say whether the footings can be reused, because sometimes they can and that is real money off the job rather than a sales line. Where the posts have gone there is nothing to repair and patching the visible part only hides it.
Block and Besser Repairs on Unanderra Clay
Bulging usually means water behind and no weep holes. Honest assessment of whether it can be saved or needs to come out. A block wall that has moved but is otherwise sound can sometimes be opened up at the back, drained properly and reset. Where the blocks themselves are cracked through, it is a replacement and we will tell you that rather than quoting a repair we do not believe in.
Seasonal Movement Allowed For
Clay swells and shrinks through the year, so the wall is loaded and released repeatedly rather than once. Built with that in mind rather than for one still day. It is the reason footing depth matters more here than in sandy ground, and the reason cheap walls on this soil fail on something close to a schedule.
Walls and Level Yards Around the Illawarra
Free draining material and an agricultural line going in behind a wall on clay, before any backfill.
Reactive Clay and Tired Walls
Clay behaves differently to sand. It does not drain, so water sits behind a wall instead of passing through it, and the weight of saturated clay against a wall face is far higher than most people expect. It also moves with the seasons, swelling when it is wet and shrinking when it dries, which means a wall here is being pushed and released over and over rather than loaded once and left alone.
That is why drainage is not an optional extra on this ground. Free draining material against the back of the wall, an agricultural line at the base with a fall and an outlet, and geotextile between the drainage material and the clay so it does not clog. Skip any one of those and the wall is holding water as well as soil. It is also the cheapest part of the job to leave out of a quote, which is worth knowing when you are comparing two figures that look a long way apart.
The older walls we replace around here usually failed for exactly that reason. Treated pine sleepers with clay backfilled straight against them rot from the back face first, so they look sound until the day they do not. Besser block walls built without weep holes or a drainage line bulge in the middle. Neither is a repair job at that point, and we will say so rather than taking money for a patch that buys a season.
When we quote a replacement we will tell you honestly whether the existing footings can be reused, because sometimes they can and that is real money off the job rather than a sales line. We will also tell you when the old wall is holding more ground than it looks like from the front, which changes how it has to come out and in what order. Taking a failing wall down in one go on a sloping block is how a bad day happens, so it comes out in sections with the new one following behind it.
More on retaining walls, landscaping, fencing and property maintenance.
How Long Should a Retaining Wall Last?
Longer than most of the ones we pull out, and the difference is almost always what went in behind them.
A wall is two jobs. The visible one is the structure holding the soil. The invisible one is getting water away from behind it. On the escarpment foothills the second job is harder than the first, because water comes down off the slope and the clay will not let it through.
Done properly, a block wall on sound footings with drainage behind it is a long term structure. Done without drainage, the same wall is a medium term one, and the failure is not graceful.
Timber is a reasonable choice at lower heights and in the right position, and it costs less. What it does not tolerate is clay packed straight against the back of it.
The question worth asking a builder is not how long the wall will last. It is what they are putting behind it, and where the water is going to come out. If the answer to the second one is vague, that is the problem.
Got a slope to hold back in Unanderra?
Send through photos of the slope and the height you are trying to hold, and you will get a straight answer on what it involves and what it costs.
Contracts, Deposits and What NSW Asks For
Renovation work in NSW comes with consumer protections worth knowing before you sign anything. A written contract is required once the contract price is over $5,000 including GST. Work between $5,000 and $20,000 can run under a small works contract; above $20,000 it needs a full home building contract, and home building compensation cover with the certificate that goes with it. The maximum deposit anyone can ask for is 10 per cent, on a small job or a large one. Variations should be agreed in writing before the varied work happens, not reconciled at the end. None of that is unique to us, and you should expect it from whoever you use.
Quoting a Unanderra Retaining Wall
Every job gets quoted on what it actually needs. We look at the access, the condition of what is already there, the materials you want and how much of the existing work can be kept, then give you a figure before anything starts. Two jobs that look identical in photos can be very different once someone is standing in the room, so we do not publish a rate card. You get a price for your job, and it does not move once we have agreed it.
Unanderra is a few minutes from Wollongong, with Figtree, Port Kembla, Cringila and Dapto all close by. Work in this pocket gets batched where the timing allows, which keeps travel off the invoice and makes a return visit for a part practical. On a replacement a first look means digging at the base of the existing wall to see what the posts or the footings are actually doing, because that is the difference between a repair and a rebuild and it cannot be judged from the front.
Plumbing and electrical work is carried out by licensed partners, not in-house.
Unanderra Retaining Wall Questions
Why do sleeper walls fail in clay?+
Because the clay sits against the timber and holds moisture against it permanently. Treated pine handles damp but not constant saturation, and it rots from the back face where nobody can see it. The wall looks fine from the front right up until a section lets go. A drainage layer between the clay and the timber is what prevents it, and most of the walls we replace never had one. Timber is still a reasonable choice here at lower heights if the drainage is done properly, so it is the detail rather than the material that decides how long it lasts.
Can a failed wall be repaired instead of replaced?+
Sometimes, and we will tell you which one you are looking at. A wall that has leaned slightly but is sound can occasionally be pulled back, drained properly and reset. A wall with rot through the posts, or a block wall bulging in the middle with cracked units, is past that. Patching those buys a season and costs you the work twice, so we would rather be straight about it. Where it is borderline we will give you both prices and let you decide with the facts in front of you rather than making the call for you.
How do I get a retaining wall quoted in Unanderra?+
Photos of the wall or the slope, the length, and roughly how much height you need to hold. For replacements a photo of the back of the existing wall helps if you can get one, because that is where the failure usually started. If the wall holds a driveway, or anything parks near the top of it, mention that, because vehicle load changes the design. You get an itemised written quote with the exclusions listed before anything starts. Call 0413 147 335.
Do you handle the drainage and the landscaping as well?+
Yes. The drainage behind the wall is part of our work rather than something for another trade, which matters because it is the part that decides how long the wall lasts. Levelling, turf, paths and fencing on top of the wall we can take care of in the same job, so the finished levels are set once instead of being adjusted afterwards by somebody else. Steps and handrails between levels are our own work too, including the steel.
Also in Unanderra: pergolas and welding. Close by, there is retaining walls in Horsley.
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