Renovation Drill Down #2: Plumbing and Drainage


This second article in our series drilling down into the finer details of renovation looks at plumbing and drainage.

Perhaps even more so than our first topic, Electricals, there are tips and key lessons to learn that can save you money and potential heartache.

Roof Gutters and Downpipes

Starting outside of the home, there are a few things to consider when choosing new gutters and downpipes.

If you are adding whole a new floor, the style and colour of the new gutters should match the existing ones or you could spoil the look of your home.

However, this is also an opportunity to choose more modern Colorbond gutters that don’t require regular painting. You can replace the old gutters at the same time, or in stages after the renovation if your initial budget doesn’t stretch.

Downpipes don’t necessarily have to be the same colour as the gutters. It might be more visually appealing to ensure that they match or complement the colour of the walls of your home.

This is where rendered sketches of your renovation or a CAD (computer-aided design) draft can help you decide what looks best. As our article on street appeal explains, taking care with the external look of your home can add to its resale value and attracts more attention at auction.


Out of all of the rooms in your home, the bathroom is likely to be the most expensive to build based on a per square metre basis. That’s mainly because of the need for waterproofing and tiling.

So getting things right first time is vitally important especially if the bathroom include features like underfloor heating … not something to rip up and start again without significant cost.

It also follows that the size and layout of the bathroom can have a significant impact on the overall cost of your renovation.

Size can be significantly affected by seemingly small details like the style of your shower enclosure and screen, but also by more fundamental decisions like the inclusion of a toilet… or even a bath!

Whether you are renovating to create your dream home, or to sell, it’s always good to consider what buyers are looking for to ensure your home can get the maximum sale price and the highest possible number of interested buyers.

Generally we find most appreciate two bathrooms, but only one needs to have a bath. If space isn’t an issue, a separate toilet offers flexibility and privacy.

From a plumbing point of view, there are several aspects to pay attention to.

With the shower, there are many options. Standard is a wall mounted shower rose, either fixed or adjustable on an sliding vertical railing.

However, you may have your heart set on something more bespoke, like a ceiling-mounted rainshower head combined with a wall mounted unit with the ability to switch between the two.

Will your bathroom have room only for a standard-sized vanity with one bowl or do you need a larger two-bowl vanity? Will the vanity be floor-mounted or wall-mounted?

If you choose a wall-mounted vanity, let your builder know well ahead of time as they will need to prepare the wall frame behind to handle the weight of the vanity hanging off it. You really don’t want your beautiful new wall-mounted vanity to fall off due to insufficient bracing!

When selecting a vanity, make sure you are also thinking about the tap set to go with it. This may seem obvious, but we’ve seen situations where a wall-mounted vanity with 3 holes for a traditional tap set was built, and a combined mixer selected which would have left two holes!


It’s also important to let your builder or plumber know well ahead of time what type of toilet you are considering.

There are a wide variety of toilets, for example ones with a back to the wall, close couple and linked suites. Additionally there are key details to consider like whether the toilet has an “S” trap (waste pipe connection is in the floor) or “P” trap (waste pipe will go through a wall).

You may also be considering a toilet with an in-wall (hidden) cistern with a wall hung pan. If so, your builder will need to make allowance for an extra wall to hide the cistern and/or ensure extra wall framing to support the wall hung pan.

If the bathroom you are designing is tight on space you may not simply have the room to fit an in wall cistern. So it’s important to keep these things in mind when finalising your bathroom layout.

Once you’ve made your toilet selection we recommend you give the specifications from the supplier to your builder or plumber so that they can ensure the necessary framing, plumbing and drainage is in place when the toilet is ready to be installed.

if you are creating a separate toilet room, it’s wise to include a small basin and hand towel rail, especially if the toilet isn’t close to the bathroom.


Like the bathroom, this is a ‘wet’ area, so it pays to design this with care to avoid an expensive rebuild.

Provision needs to be made for plumbing and drainage points for both a washing machine and a tub.

Ideally both units will be located adjacent to each other to minimise the plumbing and drainage required but also from a workflow point of view for you!


No, we haven’t forgotten about the kitchen! There are plenty of plumbing considerations for basins, dish washers and gas piping.

However, in our experience of thousands of renovations, most homeowners use a specialist kitchen designer / builder who are the experts in advising, designing and coordinating the trades required.

Talk to the Specialists

As you can see from the above, talking with your builder or plumber before making any critical decisions is highly recommended.

They should be able to tell you about any unforeseen issues you may not have considered, and can plan ahead to ensure your vision can be realised most effectively and efficiently … saving you both time and money.

Plumbing specialists such as Reece Plumbing (who have over 450 stores throughout Australia) are also worth visiting to see the complete range of product choices. They can also answer your questions about those options.

We hope this guide has given you a good starting place for planning the plumbing and drainage for your home renovation, as well as a “heads-up” about the potential pitfalls.

Be sure to also read our article about Electricals, the first in this series.

If you’re thinking of adding another room or another floor to your home and want to discuss your plans in detail, Addbuild is Sydney’s leading home additions and extensions builder offering experienced design and DA approvals services through to completion. Feel free to contact us by calling (02) 8765 1555 or by using our online form.

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