Knockdown-Rebuild Projects: Closed-Loop Recycling for a Sustainable Build
August 2024
If you’re planning a knockdown-rebuild project, have you thought about reusing timber from the house you're demolishing? Rather than letting this valuable resource end up in a landfill, recycling the timber can be a rewarding decision—benefiting the environment while infusing your new home with unique character. We regularly work with customers who are keen to incorporate recycled materials from their existing building, but who don't know how to go about it.
In this blog post, we'll guide you through the benefits and challenges of salvaging and reusing materials in your knockdown-rebuild project.
What Is a Knockdown-Rebuild Project?
In the Australian context, a knockdown-rebuild project refers to the process where an existing house is completely demolished (or "knocked down") and a new home is built on the same plot of land. This approach is often chosen when the existing house is outdated, structurally unsound, or doesn't meet the needs of the current owners, but the location or land is desirable.
Rather than renovating or extending the old house, homeowners opt to start from scratch, allowing for modern design, energy efficiency, and customised features in the new build.
Why Should I Recycle Timber From My Knockdown-Rebuild Project?
There are several compelling reasons why you might like to consider saving and recycling timber when an existing building is due to be demolished for your new house build project.
#1 — Lessen the environmental impact of your project
Recycling timber reduces the need for logging our native forests and avoids the energy-intensive processing required for new timber. This means lower carbon emissions and less strain on our natural resources.
#2 — Many old homes were built using high quality hardwoods
Many older Australian homes were framed using Australian hardwoods (including roof, wall and floor framing), while the majority of more recent buildings use either pine or steel. These old timbers just can’t be economically sourced anymore and certainly not in the quality found in many old buildings.
#3 — Retain the fascinating history of the timber
Each beam, floorboard, or joist carries the story of the structure it once supported, often bearing unique marks, patina, and character that only time can create. By incorporating this timber into your new home, you’re creating a tangible connection between the past and present, adding depth and a sense of continuity that modern materials simply can’t replicate. Your space won't only looked more interesting, it will feel different.
If the house you’re demolishing has been in your family for generations, preserving the existing timber can also offer a meaningful way to maintain a connection to the past. By incorporating this wood into your new home, you’re not just salvaging materials—you’re retaining a tangible link to the memories and lives that shaped the house over the years.
#4 — Increase the value & appeal of your house
Incorporating recycled timber into your new home can give it a unique edge in the market. The character and history of the timber stand out, making your property more appealing and potentially boosting its value. Plus, eco-conscious buyers will appreciate the sustainable practices integrated into the build.
How Thor’s Hammer Can Help With Recycling Your House Timber in Your Upcoming Knockdown-Rebuild
We can support you through many of the important stages of recycling your house timber. Here’s the rough process we’d walk you through:
Step one: Assessment
We help evaluate the quality of the timber. You can send us photos or schedule a site visit (with an hourly charge) for a more detailed assessment.
Step two: Challenges
We’ll help you to identify any potential issues or roadblocks involved in reusing your timber, with particular attention to the quality and location of the timber. For instance, timber with heavy paint or structural damage might not be ideal. Hardwoods are usually more valuable, while painted, damaged or particularly naily timber may require additional processing, making them a less economical choice for recycling.
Step three: Demolition & Salvage
It's important to decide who will be handling your demolition well in advance. We have a network of demolition companies that we can connect you with. The timber will need to be properly packed and transported to us that that we can easily handle and process it. Many demolition companies are not set up to do this, so if you decide not to go with one of our recommended companies, it's important to confirm that they have this capacity if you're planning to save the demolition timber from your knockdown.
In Canberra we work closely with and can highly recommend Brucic Constructions, who do a great job of saving timbers.
There are also a number of builders who are willing to do both the knockdown and the rebuild and will recycle all the materials in your old home. In the past we have worked with 360 Building, Edward Robert Builders, Grandview Constructions and SJM Building.
Photos: Timbers from the demolition of a house having been carefully disassembled, stacked, measured, counted and sorted on site by the team at Ewer Constructions before being delivered to our workshop. Learn more about how this great timber was reused in the Hackett Gardens house by Ben Walker Architects.
Step four: Storage & Processing
Between the knockdown and rebuild phases, it’s crucial to store your timber safely and keep it as dry as possible.
If storing the timber on the building site isn’t feasible, we offer storage services in our timber yard. This option is especially convenient if we’re processing the timber for you (or transforming it into custom-made furniture or joinery elements), as it provides added flexibility in case your construction timeline shifts.
We also have a solar-powered kiln on site that can be used to dry your timber if needed, depending on its intended application.
Once the timber arrives at our facility, we handle the denailing and metal detection, which can vary in cost depending on the quality of your timbers. Depending on the future use, we can dry it in our solar kiln, and then produce flooring, decking, cladding, benchtops or furniture as suits your project.
FREQUENTLY ASKED QUESTIONS
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Painted timber is generally not good for recycling as we can’t dress it (our sawdust goes into briquettes and paint often has metals in it which blunt blades extremely quickly). If we are going to wire brush or grind the paint off then it needs to be checked for lead first using a lead testing kit.
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Flooring is difficult to salvage without damaging it. There are some important things to think about when considering the salvaging and reuse of a homes existing timber flooring:
Do the floor boards have enough thickness above the groove? Minimum 5mm.
If flooring has been coated with a thick polyurethane the tongues and grooves will often be glued together and the grooves will all break when it is being lifted.
Staples in a floor should be removed before pulling up the floor.
Nails in flooring need to be pulled through from the back. If they are hammered through the head of the nail will blow out the top of the board.
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There are a few important things to consider when recycling structural timbers during the demolition of an existing home.
Cut roofs have larger timbers and are the best for recycling. Truss roofs are generally not worth recycling - even 1970’s hardwood trusses. Lengths end up being very short and truss plates are often too hard to remove.
Timbers less than 100mm wide or 38mm thick are sometimes not worthwhile. Smaller timbers are more labour intensive to de-nail per cubic metre of timber processed.
Floor joists have too many nails and are expensive to de-nail. Sometimes nails are too rusted to pull out and they break.
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If you are considering recycling the timber from your knockdown for use in your new build, we certainly recommend having a chat with us early on in the process. - we will gladly give you a lot of assistance and helpful advice. You are welcome to drop past our showroom any time and we will be able to have a look at your project together. If you have a very complex or detailed project it is worth giving us a call or email to set up an appointment.