Guide to House Extension Costs

One thing you know for sure: you are outgrowing your existing home. What you aren’t sure of is whether or not you can afford a home extension. There are many costs to consider that you may not be aware of and it’s important that you be aware of all of them before you decide whether or not you can afford to add on a room. This brief guide to house extension costs is designed to help you avoid overlooking anything and consider all of your options. The next step is to find a home extension professional in your area.

Owner Builder vs Hiring a Building Contractor

Many homeowners wanting to add on a house extension decide to do it themselves and become owner builders. This can save you money, but there are many costs and legal obligations you need to be aware of. Just some of them include the cost of an owner builder permit, ongoing building permits and inspections and insurances. Have a look at a few of the dozens of owner builder articles on Home Improvement Pages and you will get a better idea about whether or not you want to go this route.

A local builder can take a lot of the guesswork out of your house extension cost estimating, so you may want to get a quote or an estimate from one or two in your area to begin with. However, in order to make an informed decision, it is best to make a list the major expenses in materials and labour before you decide which contractor to use or whether to get an owner builder permit and take on that responsibility yourself. These are some of the major things to consider:

  • Is any excavating required? If so, you need to find out how much that is going to cost before you do anything else.
  • Make a list of your basic building materials. These may include cement work for your foundation, framing materials, internal and external cladding, roofing materials, insulation and other costs associated with your basic structure. Start from the ground and work your way up, just as you will do when you start building. You can get a reasonably accurate ballpark figure by measuring the square metres of your house extension and using an online cost calculator, but your list will help you get a firm idea of any extra costs that may be involved in your project.
  • Make a list of your interior finishing materials. For example, do you want a timber floating floor or will your house extension be carpeted? There are significant differences in the prices of flooring materials and related installation costs, so you may want to consider several different options.
  • Don’t forget the cost of lighting, electrical work and plumbing, if any. These are all important costs to consider and you will need to get a licensed electrician and/or plumber to do the these jobs for you, even if you have an owner builder permit.

As you make your list of house extension costs, you will no doubt think of many other things you need to include. If, when you add it all up, it turns out to be outside the scope of your budget, don’t despair. There are many cost saving alternatives you can consider. For example, if you want more living and dining space, maybe a patio extension is all you need.

To see more ‘price of’ guides visit the ‘Cost of homes services‘ page to see a full list.


Builders Quote