There is no such thing as ‘away’ when it comes to demolition waste. So, if you’re weighing up a knock-down rebuild or a partial demolition in your renovation, there’s a lot you can do to reduce what ends up in landfill.

In this episode, I share what to consider when reducing demolition waste, and how to work with your team to salvage, reuse and recycle the materials in your existing home.

Listen to the episode now.

Hello! This is Episode 437. This is Way #37 of the ‘44 Ways to Create Your Sustainable Home’ series, and we’re continuing through Section Eight: Sustainability During Construction.

Way #37 is: Reduce Demolition Waste.

If you’re doing a knock-down rebuild, or demolishing part of an existing home to renovate, there’s an enormous amount of material that comes out of that building.

There is no such thing as ‘away’ when we think about the waste that generates. It all has to go somewhere, and it often goes into a hole in the ground. Over 40% of Australia’s waste is from the construction industry, or around 27 million tonnes per year. Around 20,000 residential demolitions are approved each year, with over 95% of those being individual homes.

When it comes to demolishing houses…

I meet a lot of homeowners who are weighing up whether to renovate their existing home or knock down and rebuild a new one. 

It’s a challenging comparison. Because chances are you have entirely different expectations of both outcomes and different budgets as well. 

Many can consider the ‘value’ they’ll get from a knock-down rebuild is greater than a renovation. So they’re willing to spend more on achieving it. They see that a knock down rebuild (KDRB) will deliver a new home, custom built from scratch for them, with a design that is to their choosing. 

If you’re comparing KDRB to working with an existing house, you might find the renovation means significantly massaging the existing floor plan. The home may have undesirable features or existing problems in its design and construction. In these cases, people often tell me the KDRB feels like it’s working harder for their financial investment.

And interestingly, due to the labour involved in working with a retrofit or renovation, and upgrades required to its existing condition, sometimes a KDRB can actually work out to be the same cost or even slightly less, than renovating an existing home.

A retrofit or renovation can involve removing asbestos or other unsafe materials and services, and money can get spent on selective demolition that feels invisible. Then, you’re trying to reconfigure existing spaces, potentially extend the home, work with existing structure and older materials, and improve the thermal performance as well. 

People often expect to spend less on a renovated outcome than a KDRB, and some see the existing house as a handicap to their future home goals, instead of a headstart.

And unfortunately, it will always be cheaper and faster to demolish an entire home in one go, than to selectively demolish or cherry pick items out of it for reuse and repurposing.

The upshot of all of this if this is what you’re weighing up? 

Well, I think for starters, it’s important to acknowledge that you’re not comparing apples with apples. 

So, I’d encourage you to consider this: instead of just looking at the outcome you achieve and what value you place on it when comparing a renovation to a KDRB, don’t ignore what you’re throwing away in the materials, products and labour in the existing home. Not just in their financial worth, but also their resource value and embodied carbon. 

I personally love a renovation, and feel it’s such a beautiful opportunity to consider how you can breathe new life into an existing home. I also struggle with the demolition of an existing home. I feel that most homes are salvageable, but it does take an adjustment in expectations. And I think that’s often the sticking point for homeowners. I know not everyone thinks like I do, and I’ve worked with clients who, for them, a brand new house was the goal regardless of the state of the existing dwelling. They just wanted a home no one else had lived in.

Let’s look at what you can consider when reviewing potential demolition of part or all of an existing dwelling: the pre-demolition audit.

A pre-demolition audit is a systematic walk-through of the building to document what’s there and what can be recovered. It recognises that there’s inherent value in the existing building, and seeks to extract that for both financial and environmental benefit.

The audit considers what materials can be salvaged for direct reuse, what can be recycled, what needs specialist handling, and what will genuinely need to go to landfill. It needs to happen before anything comes down, because once a wall is knocked down without care, the materials are damaged or contaminated beyond recovery.

The materials worth looking for in an older home can include structural timber from the roof and floor framing, which is often great quality hardwood. Brickwork that can be cleaned and reused. There’s also solid timber flooring, doors and windows, particularly older timber joinery. Hardware: door handles, hinges, tapware, light fittings. And services materials, particularly copper pipe, which has strong recycling value even if it can’t be directly reused.

Let’s talk about deconstruction versus demolition…

Deconstruction provides for the careful, systematic dismantling process that preserves the integrity of materials so they can be recovered. Selective dismantling of the highest-value elements before the rest of the building is cleared can recover significant material without turning the whole project into a salvage operation.

The best outcome is that the material goes straight back into your project. Structural timber can be repurposed into flooring, joinery, or furniture. Reclaimed bricks can become a feature wall, paving, or landscape elements. Old doors can be refinished and rehung. This keeps the material on-site, eliminates transport, and gives the new design a connection to the history of the place.

Before any demolition work begins, you need to know whether asbestos or lead paint is present in the building. Both require specialist management before other work can proceed.

In this Episode, I cover:

• The scale of construction and demolition waste 
• How to think about KDRB vs renovation beyond just the financial comparison, including embodied carbon and resource value
• Why demolition plans could be renamed ‘repurposing plans’
• What a pre-demolition audit involves, who should do it, and why it has to happen before anything comes down
• The materials worth salvaging in an older home
• The difference between deconstruction and demolition, and how specialist contractors can work with you
• How to use salvaged materials in your project, through marketplaces, or by selling kitchens and fixtures ahead of a site start
• Recycling pathways for concrete, masonry, metals and plasterboard
• What needs specialist handling 
• What to put in your brief, contract and documentation so demolition contractors don’t smash what you wanted to keep

Plus a whole lot more.

LISTEN TO THE EPISODE NOW.

RESOURCES:

Episode 429, on choosing for recyclability and low waste >>> 44 Ways #29

Waste Today Magazine article on diverting construction and demolition materials from landfill >>> Diverting C&D materials from landfills

UK Government statistics on waste >>> UK Statistics on Waste

A free guide to simplifying sustainability across research, planning, design, materials, and building, from Amelia Lee’s 30+ years in residential design and construction >>> 44 Ways to Create a Sustainable Home

Access the support and guidance you need to be confident and empowered when renovating and building your family home inside my signature online program >>> HOME Method