If you’re an Australian owner builder gearing up for a new home or reno, plumbing probably isn’t the first thing on your mind but it should be because understanding the basics of plumbing can help you make smarter decisions during the design phase.
In this first blog of our 4-part series, we chat with licensed plumber Nathan Rich from KNR Plumbing, who kindly shared his time and straight-talking advice to help you plan with confidence.
Based on the sunny Sunshine Coast, Nathan explains what every owner builder should know before the first trench is dug or a pipe goes in.
Let's dive in!
What Are the Different Types of Plumbers?
Not all plumbers are the same. According to Nathan, “There are so many different types of plumbers, but for owner builders, it usually comes down to a residential construction plumber“.
These plumbers specialise in new builds and renovations, not general maintenance work.
“Some plumbers do a bit of both,” Nathan explains, “but if you’re building or renovating, you want someone experienced in construction plumbing.”
What About Roof Plumbing?
This is where things often get confusing. Does your plumber also do your roof drainage?
“Roof plumbing is a thing,” Nathan says. “But these days, it's typically a separate trade. Your roofer will handle everything from the gutters up, and your plumber takes care of everything from the gutters down.”
So, if you’re getting a Colorbond roof installed, expect the roofer to manage gutters, while the plumber installs the downpipes and stormwater system.
Who Designs the Plumbing Plan?
It starts with your architect, building designer or draftsperson. They'll generally lay out the bathrooms, kitchen, and laundry. But it's the plumber who designs the hydraulic and drainage plans from there.
“We work off the architect's plans and then figure out how to get drainage and vent pipes in the right places,” Nathan says.
This means your plumber comes in after your plans are approved and does a deeper dive into how to actually run water and waste pipes efficiently.
What Should You Think About During the Design Stage?
Most owner builders understand that electrical planning matters (think light switch and power point placement), but plumbing choices can be just as critical.
Here are a few things to consider early:
- Fixture types: If you want a wall-hung toilet or in-wall cistern, your wall cavity must be deep enough (90mm minimum).
- Stone baths: They look amazing but can weigh over 300kg when full. Ensure your floor and engineering can handle the load.
- Bench height + countertop basins: Be mindful of ergonomics. A high bench plus a sit-on basin can make brushing your teeth feel awkward.
“If you're using a countertop basin, I usually drop the vanity height down to 800mm instead of the standard 900mm,” Nathan explains.
These are the sorts of details best discussed during the design phase, not after construction has started.
What's next in the Plumbing Series?
There’s more to plumbing than pipes and water. The early design decisions you make can set the tone for your entire build and Nathan’s tips are just the beginning.
In the next part of the blog series, we'll cover common plumbing mistakes and how to avoid them, including what happens if your plumber doesn't do a proper rough-in and why rushing the job can cost more in the long run.
Stay tuned Owner Builders 🏡
About Nathan Rich – KNR Mechanical Plumbing
Nathan runs KNR Mechanical Plumbing on the Sunshine Coast and has built a solid reputation for being friendly, down-to-earth, and great at what he does.
With loads of experience in residential builds and renos, Nathan takes pride in doing the job right. No shortcuts, just honest advice and quality work.
If you’re after a plumber who actually cares about your build and has experience working with owner builders, Nathan’s your guy!
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