Knockdown Rebuild Q & A


Kato MK2 Home

A knockdown rebuild can be a viable alternative to buying a home or doing a major renovation, however, it’s important to go into the project with eyes wide open when it comes to considering this option. To get the most out of your building experience you need to engage a builder who tells you upfront what is involved and what the actual cost will be. Too often, people discover hidden surprises along the way or find out not everything they’d imagined for their home is included; like discovering after the builder has downed tools and walked away from the site that landscaping and fencing are still be done.

We asked our resident knockdown rebuild specialist and Senior Design Consultant Wayne McPhee, what are the most important questions you should ask when thinking about this kind of building project.

How much does it cost to knockdown and rebuild?

Most demolitions range in cost from $15,000 to $30,000 depending on the size of the home and the asbestos content. In addition, demolition also usually covers the removal of driveways to the boundary, retaining walls, sewer, water and stormwater pipes underground, clotheslines and trees, shrubs and gardens if you wish. Although in some locations local council’s separate approval may be required for the tree removal. The site will be cleared ready for a new building to be erected.  

What happens once the old house is demolished?

The Engineers doing the test will classify the lot as a “P” site being “Problematic”. Do not be alarmed. This just tells everyone that reads the soil report that something has happened to the lot requiring additional engineering attention. This “P” is due to the soil being “fluffed” up during the excavation of pipes, stumps and will lose its bearing capacity for the next house to be built on. This will result in slightly higher footings and engineering costs as these will have to go through the “fluffed” up soil into the natural soil below usually at least 600mm. The cost of this is more expensive than an empty block but is not significant enough to prohibit the building of the new home. The cost varies depending on the block and house design too.

Could there be any unknown costs when knockdown and rebuilding?

Additional costs that also will be encountered is the Demolition Approval from a Building Certifier or Local Council which is around $1,000. The disconnection and capping of the water and sewer pipes by a licenced plumber will cost between $600 and $800 and is generally done the day before or the morning of the demolition. The above two items may or may not be included by the demolition company in their quote. The other item that needs to occur is the disconnection of the electricity. The energy authority generally will only speak with the homeowner directly and not your builder or demolition company. This conversation should take place early in the process to ascertain how much time they require to organise and do the work. Generally, 4 to 6 weeks before demolition is required, but this does vary and will need to be coordinated by the homeowner to have it done before the demolition day. This will also dictate, to an extent, the move out date of the homeowner and may, depending on the authority, take place weeks before the demolition company can be on site.

How long does it take to demolish a house?

Demolitions normally only take up to three days but can take up to five depending on the weather.

Will the demolition pay me for the materials salvaged from the home?

People often think the Demolition Companies will pay them for their home or salvaged materials. In some instances, this may be the case but in the vast majority of cases, it does not apply. If you can get them to take it away and do the associated site works at no cost, then that is a cost-saving by not having to pay the above-outlined costs, however, this is not a regular occurrence. Demolition and recycling yards are currently oversupplied, only a house with redeeming features is worth their time and money to salvage.

What should I look out for in a demolition agreement?

In most demolition agreements, when you accept the quote, the house structure and attachments become the property of the demolition company and items cannot be removed by the homeowner unless previously discussed and approved by the demolition company. Always read the demolition quotes carefully.

Who organises the demolition?

GW Homes can assist you in including the demolition costs as part of the new build contract and coordinate this for you if you wish. If you are borrowing, check with your lender first to ensure they will be happy to have the demolition costs included in the loan or whether you will need to fund the demolition costs yourself.

Our qualified professional new home design consultants are here to help you build the home of your dreams. Our staff can answer all your questions and streamline the entire process. Email us or call 07 3393 1399.

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