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Extending Your Home

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Extending Your Home

by Allan Staines

So, it’s settled, you want to keep your address and extend. What is the best way to approach siting an extension?

Firstly, if the layout of the present floor plan provides an obvious position for your extension, all is well. This means that there already exists an obvious siting for access to the new space. Maybe the additional space is simply the extension of an existing room. This is the ideal situation, but doesn’t always occur.

Where the extension is to increase the square metreage of a smaller house, decide if it will be more advantageous to alter part of your existing floor plan to improve the layout. When planning the ideal place to add more space, ignore the present uses of existing rooms in order for the imagination to be uninhibited. You may end up changing around a number of existing living areas in your new design. For example, although you may be extending to gain a family room, it may be better all-round to call the new extension the lounge and convert the existing lounge into the family room. These proposals are not always obvious until all preconceived ideas are put aside.

Draw a scaled floor plan of the existing house or take a copy from the original house plans. Remove the names of existing rooms so that you can commence as an artist would with a blank canvas then add on the lines of the extension. Then redesign the room layout.

Siting the Extension

This stage may need to be approached prior to designing the layout especially if you are reshaping the overall floor plan. When a choice has to be made as to which side of the house is best to extend, the roof line and ground contour is the major structural consideration. Costs can be increased or reduced depending on the particular part of the roof chosen for alteration and the height of the proposed new floor plan above ground.

Where the new roof is simply an extension of an end-gable, this offers the cheapest roof extension. One which simply extends a hip-end offers the next cheapest option while any extension which will require two new valleys to be formed at the junction will be the most expensive.

The higher the proposed floor is above ground level the greater your building costs for sub-floor walling, unless the floor is to be only supported by stumps or columns.

How to Approach the Actual Building

Firstly, construction plans will have to be approved by your Local Council.

It’s a good idea to have a booklet specification prepared by the designer. This may cost extra however it will help avoid a lot of on-site disputes with subcontractors. Using a plan only does not spell out the many specific requirements of the owner and of the building code. A plan without a booklet specification is only suitable for builders who have subcontractors who are completely familiar with the builder’s requirements.

Once you have plans, you can obtain quotes for construction from two or three builders. Choose one who is experience in extension-type work and who has been recommended to you for previous work well done. Request a time limit to complete the extension so that you can know just how long you will have to be inconvenienced.

Do everything in writing with builders or subcontractors. You can use the Australian “How to be a Successful Owner Builder & Renovator” as a guide as to how to proceed and how to handle the building process. It’s a good reference.


Allow extra in your budget for the unforeseen. The project may be tedious but in the end you will have the house just how you want it without the upheaval of changing your address.

Return to Ground Floor Extensions

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