To go up or out? Home Additions vs Extensions

When it comes to adding space to your home, the choice between a ground floor extension or a first floor addition is often made for you by your block size, house construction / layout or other factors.

For many people though, extending either up or out are both realistic options, so here we take a look at both to help you decide which approach might suit you best.

Ground Floor Extensions

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If you have the room on your property to extend outwards, a ground floor extension could be a good option. Ground floor extensions are ideal for creating more living space and opening up existing spaces to the outdoors.

The main drawback of a ground floor extension is that it usually results in a loss of some of your outdoor space. However, if you’ve got plenty of room or if you’re not currently making use of this outdoor space, this won’t be a problem for you.

In some cases it can also be a more expensive way of gaining extra space – when compared with a second storey – particularly where the ground the extension is to be built upon requires significant preparation work and/or extensive foundations.

Why choose a ground floor extension?

  • More living or entertaining space
  • Want an open plan living space
  • Want to open up the living space to the outdoors
  • Current layout does not suit
  • Preferable solution for people with mobility issues


  • Lets you open up living spaces to the outdoors
  • Able to be added to most houses (provided it meets regulatory requirements)


  • Requires some of your outdoor space to be given up
  • May result in loss of existing gardens, lawns and paths in the building area
  • Can be more expensive than a second storey addition due to excavation and/or foundation costs

First Floor Additions

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If you need more room but don’t want to extend outwards, extending upwards is your best option. A first floor (second storey) addition can be added to most houses and for less cost than you might think.

While they can be disruptive (as all building works are), in the majority of cases it is still possible to live in your home while an addition takes place. First floor additions are perfect for adding extra bedrooms, creating separate living spaces and are ideal for growing families.

In many cases they can be more cost effective than adding a ground floor extension to a home because, being built on top, they avoid potentially expensive ground preparation and/or foundation costs.

Additionally when it comes to selling your home in the future, many real estate agents will tell you that a two storey home typically has a higher resale value than a single storey dwelling with the equivalent number of bedrooms and bathrooms.

Why choose a first floor addition?

  • Needing extra bedrooms for children or extended family
  • Needing a second living space separate to the main living space
  • No room to extend at ground level
  • Want to capitalise on potential views


  • No need to give up any of your outdoor space
  • Can give you views
  • Can be a more cost effective solution than a ground floor extension
  • Can have a higher resale value than an equivalent single storey dwelling


  • Not suitable for all houses
  • Requires loss of a small amount of ground floor space for stairs

Staying put?

Many people choose to stay in their homes during the building works, to save on costs and the need to relocate both people and possessions.

How do extensions compare to additions when it comes to the impact on your family during construction? Let’s take a look:

Ground floor extensions

Provided that you’re not planning to remodel your kitchen or the old bathroom at the same time as adding on the extra rooms then in the vast majority of cases you should be able to remain in your house while the new extensions are being added.

Assuming there is no need for you to vacate your house during the construction of your ground floor extension it doesn’t mean it won’t get a bit dusty and noisy at times! At the end of the day it is a construction site and so will be subject to the same sort of conditions you would associate with building a new home.

The good news is that in most cases the work will occur during daylight hours and during the normal work- week (unless you and you builder make some special arrangements for work to be carried out outside normal “tradie hours”). So unless you work from home, have a pre-school child who sleeps during the day or you are a shift worker the noise is unlikely to impact you too much.

First floor additions

Whilst in general the comments about noise and dust equally apply to first floor additions the good news is that in many cases their impact in terms of time can be far less. This is because work is conducted on top of your home (rather than at ground level).

After the roof of your house is removed (in the area where the second story is to be built) the floor for the new addition is laid. On top of the new floor goes the wall frames and the roof structure for the second storey. Windows, external wall cladding and roof tiles follow.

All this work occurs outside your existing home with the builder’s tradespeople accessing the new second storey by ladders and scaffolding. This is known as getting your new addition to the “lock up” stage whereby it is protected from the weather. Until lock up is reached, access to the new addition is achieved by external means so the impact of noise and dust inside your house should be minimal.

Following lock up the internal work begins. In many cases even then the level of noise and dust may not be too bad until the latter stages where an opening is created in the downstairs ceiling to accommodate the new staircase. When that time comes a little patience with the noise and dust is required.

Got questions?

We’re always happy to help, and can arrange to come out to look at your property to advise on whether a ground floor extension or first floor addition would be the best option for you. Feel free to call us on (02) 8765 1555 or send us a message using our contact form.