Where Your Demolished Glen Waverley House Actually Ends Up

A demolished three-bedroom house does not disappear. It becomes somewhere between eighty and a couple of hundred tonnes of material that has to be loaded, carted and legally disposed of, and that disposal is one of the largest single costs in the job.

It is also the part of a quote that varies most between contractors, and understanding why explains a lot about the numbers you are comparing.

Disposal is charged by weight, not by truckload

This is the fact that drives everything else. Licensed facilities charge by the tonne, and the rate depends on what is in the load.

Clean, separated material is cheap to dispose of, and some of it is worth money. Mixed material is expensive, because someone else now has to sort it. Contaminated material is the most expensive of all.

So a contractor who sorts on site has genuinely lower disposal costs than one who puts everything into one bin, and that difference shows up in the quote. A price that looks competitive is often just a contractor who separates properly. A price that looks too cheap is sometimes a contractor who has underestimated the tonnage.

Concrete, brick and masonry

This is the heaviest stream and usually the largest by weight — slab, footings, driveway, paths, brickwork.

It goes to a crushing facility, where it is processed into recycled aggregate and crushed rock used as road base, pipe bedding and fill. It is a genuinely established market rather than a token gesture, and clean concrete is one of the cheapest things to dispose of.

The word doing the work there is clean. Concrete with reinforcing mesh in it is fine, because the steel is separated magnetically. Concrete mixed with soil, plasterboard or general rubbish is not, and it gets charged accordingly.

Metals

Steel roof sheeting, structural steel, reinforcing bar, copper pipe, electrical cable, and the hot water service all have scrap value.

Metals are pulled out during the demolition and go to a scrap merchant, and on a house with a steel roof and a decent run of copper the return is not trivial. A contractor who is recovering metals is reducing both their disposal weight and their costs at once. If a quote is noticeably lower than its competitors, this is often part of the reason and it is a legitimate one.

Timber

Timber splits into two categories, and the split matters.

Clean, untreated timber — framing, floorboards, roof trusses — can be recovered. Some is resold as reclaimed timber, particularly older hardwood framing and floorboards from the sort of mid-century Monash homes that come down regularly. The rest is processed into mulch or fuel.

Treated, painted and engineered timber is a different matter. Treated pine, painted weatherboards from a period where lead paint was standard, and glued products like particleboard cannot go into the clean stream. They go to landfill, and they are charged at the higher rate.

Plasterboard, glass and the awkward middle

Plasterboard is a nuisance stream. It is recyclable in principle and some facilities take it separately, but it contaminates other streams easily, and gypsum in landfill has its own problems. Glass from windows is similar: recoverable if separated, worthless if smashed through the rest of the load.

These are the materials where the difference between a careful and a careless contractor is most visible, because both of them are easy to simply throw in with everything else.

Asbestos: a completely separate path

Asbestos does not enter any of the above streams. It is removed before demolition begins, by a licensed removalist, wrapped and labelled, and taken to a facility specifically licensed to receive it.

It carries its own documentation trail — waste transport records showing where it went, and where required an independent clearance certificate. Those documents are worth keeping with your property records. Asbestos disposal is charged at a much higher rate than general waste, which is exactly why an assessment before quoting matters so much: it turns an unpriceable unknown into a line item.

Soil and fill

Soil is the stream people forget, and on a knockdown rebuild it can be significant. Excavated material has to be classified before it can be disposed of, and if the site has any history of contamination, that classification determines where it can go and what it costs. An old service station site and a suburban back yard are not the same transaction.

What this means when you are comparing quotes

Three practical points.

First, an unusually low disposal component is a signal, not a bargain. Either the tonnage has been underestimated, or the material is being assumed into a cheaper stream than it will actually qualify for. Ask what tonnage the quote assumes.

Second, ask what gets separated and where each stream goes. A contractor who can answer that specifically — this facility for concrete, this merchant for metals, this one for the residual — is running an organised operation. Vagueness here usually means everything goes in one bin.

Third, ask for the disposal documentation at the end. For general waste it is good practice. For asbestos it is essential, and you should not accept a job as complete without it.

Recycling on a well-run demolition is not a marketing line. On a typical Monash house the great majority of the material by weight leaves the site as concrete, brick and metal, all of which have somewhere useful to go. The part that ends up in landfill is much smaller than most people assume, and how small it is depends almost entirely on who is running the job.