Comparing a timber building to a concrete one by structure cost alone is like comparing two cars by the price of the engine. The engine matters, but it's not what you pay to own and run the car.
I've seen plenty of timber schemes dropped after a quantity surveyor priced the CLT against the concrete slab, line for line, and found timber dearer. Sometimes it is. But that comparison usually leaves out most of the places timber saves money.
Where timber costs more
Let's be straight about it. The structural material itself is often more expensive in timber than in concrete, per square metre of floor. Add the extra fire linings, acoustic layers and specialist connections, and the structure line in a cost plan can come out higher.
If that's the only line anyone looks at, timber loses.
Where timber saves
The savings are spread across the cost plan, which is why they get missed:
- Foundations and transfers. A timber structure is often quoted at around a fifth of the weight of an equivalent concrete frame. Lighter buildings need smaller footings and piles, and on poor ground or over a basement, that can be a big number. Sometimes it means an extra storey on the same foundations.
- Program. Prefabricated timber goes up fast. A floor of CLT can be installed in days rather than the week or two for a concrete pour cycle. A shorter program means lower preliminaries, less site overhead and earlier completion.
- Holding costs. Finishing earlier means interest stops sooner and rent or sales start sooner. For a developer, that can outweigh the structure premium on its own.
- Crane and scaffold. Lighter loads mean a smaller crane, and panelised façades can reduce the scaffold needed on the outside.
- Fewer wet trades. No formwork, no reinforcement fixers, no concrete curing time on the upper floors. Fewer trades at height also means less to manage.
- Finishes. Where timber is left exposed, it is the ceiling finish. That's a line of plasterboard and paint that disappears.
The trap: compounding percentages
Here's the subtle one. Many cost plans calculate contingency, margins and preliminaries as a percentage of the base build cost. If timber starts with a higher structure line, every percentage on top of it grows too, even though the program is shorter and the risk is different.
Comparing the two schemes properly means pricing preliminaries on the actual program, not as a percentage, and setting contingency on the actual risk.
How to get a fair comparison
- Price two complete buildings, not two structures. Include foundations, program, preliminaries, finishes and holding costs in both.
- Use real timber quantities. Brochure spans and rules of thumb make bad cost plans. Concept sizing gives the QS volumes they can price.
- Get market prices. Timber pricing moves with the supplier, the region and freight. Two or three supplier budget prices beat a rate from a cost guide.
- Expect a revision or two. It often takes a couple of rounds before a cost plan reflects how a timber building is actually built.
WoodSolutions publishes free cost guides for apartments and aged care that walk through these savings in detail. They're a good starting point for any QS new to timber.
What we give your QS
Every Timber Concept report includes the quantities and cost drivers your QS needs: panel areas and thicknesses, member sizes, the supply options in your region, and a list of the savings to look for. It won't replace a cost plan, but it means the cost plan compares like with like.
If your timber option is about to be priced, send it to us first.