Sewers and renovations

Nobody likes to think about sewerage but, if you’re planning to extend your home, chances are you’ll find yourself rather preoccupied with the topic. If you’re unlucky enough to have a sewer pipe running through your property you’ll need to do a bit of research before you start planning your renovation.

The first essential piece of information you’ll need is your sewer diagram. There is one of these for every property in Sydney, and if you don’t have a copy you should contact Sydney Water to get hold of one.

This diagram gives you essential information about the location and size of sewer pipes and maintenance hatches that affect your property. These are drawn up when the sewer pipes are laid and usually date back to the original subdivision of the area. If modifications have been made over time these should be noted and dated on the diagram.

It’s important to note that, although these documents provide useful information, Sydney Water does not guarantee their accuracy. For this reason, if it appears that a pipe is likely to impact on your proposal the most sensible first step is to have it accurately located.

You will need to contact a Sydney Water Quick Check agent in your local area who will direct you to a contractor who can carry out this work for you. The contractor will peg out the sewer line and you can use this information to help you plan your building work.

If the sewer line runs across an area you are planning to build over, you have two options. Firstly, if you have enough space the sewer can be diverted. If, however, this is impossible and you definitely need to build over the sewer, don’t panic.

It is possible to build over sewer lines, but there are strict guidelines for doing so. Sydney Water provides a downloadable document at www.sydneywater.com.au/Publications called Guidelines For Building Over/Adjacent To Sydney Water Assets which is essential reading if you’re planning this type of construction. This applies whether you are planning a full masonry building or a lightweight deck.

In general, all sewer pipes must be encased with concrete before construction can commence to avoid damage to the sewer. Obviously the prevention of structural damage to a sewer pipe is the most important factor as leakage can result in both serious health and structural problems.

Your building’s footings must then be carefully designed by a structural engineer to take into account the presence of the pipe. Enough clearance must be provided on either side of the pipe as well as above.

Maintenance access is also essential. Pipes of certain materials, such as cast iron, will need to be replaced with an approved material and then encased in concrete. All of this can be costly, but may well be worthwhile if it means you can gain the additional floor area you need.

As with all design and structural issues, planning is the key. Make sure you have all the information you need before wasting time and money on gaining approval for a proposal that simply cannot be built.