Event Review | Anne Minors
Thursday 2 May 2024
The gathering was held in the entertaining and catering space at the top of Heyne Tillett Steel’s (HTS) office where the firm’s appreciation of CLT was directly expressed in the surrounding wall and roof structure and finishes.
Michael Stiff introduced the topic of debate with different views of structural timber within the building industry. Architects consider timber as a structural material when extending existing buildings. Creative conversations between professionals often focus on the liking of timber but wanting the assurance of concrete. Many contractors are still against concrete dues to difficulties with waterproofing.
Structural concrete combined with a steel frame is competitive with timber in sustainability terms.
Michael thanked HTS for the use of their space and the evening’s catering.
Jane Wernick Chairperson
For sustainable futures we have to think about building less, building more efficiently and not building at all. In asking ‘is timber the new concrete’, consider:
Timber is a well-loved material, from the trees themselves to the buildings, finishes and furniture made from them. They have warmth in look and to the touch. Tress are the only source of carbon capture.
Timber is less suitable for foundations, vertical structures, resisting fire, long span floors. For these elements, can concrete fight back with low carbon concrete?
Votes before the debate: Yes - 18 No - 34
Speaking for the motion:
Laura Batty Senior Associate Research & Innovation,
Heyne Tillett Steel
Timber is versatile and can be used the same as concrete for floors, walls, roofs, foundations.
Functionally it is both the older material and the newer material compared to concrete. High performance timber is very new.
Concrete has been through many more insurance considerations than timber and it is a struggle for timber to displace concrete from this position.
Morally we should be trying to use more timber because:
SPEAKING AGAINST THE MOTION
Elaine Toogood Director Architecture & Sustainable Design
The Concrete Centre
Concrete is the worlds favourite building material. Raw materials and skills are easily available. Concrete - foundation on which modern society is based producing 30 Billion Tonnes globally.
Timber is unlikely to replace this amount of concrete.
The first reason to use concrete is that performance of concrete for different applications is high:
Second reason for using concrete is its availability:
Plant more trees- competing with space to feed a new population.
In England, concrete footprint of land is 0.1% so little conflict with food production for land.
Permits and phased restoration have led to biodiversity nett gain in UK.
Clear roadmap for decarbonising concrete exists and making good progress.
There has never been just one type of concrete.
Concrete is the new concrete.
SPEAKING FOR THE MOTION
Andrew Waugh Director,
Waugh Thistleton Architects
Timber is not the new concrete
We have been using timber for much longer
Positives:
Caution:
We have to be careful with the provenance of timber.
SPEAKING AGAINST THE MOTION
Sam Draper Director,
Seratech
Concrete and timber are different materials. Reductive to pit them against each other. They work together and can create regenerative built environment.
Concrete emissions cut by 50% since 1990 - plans to reduce emissions to zero by 2030.
Mineral Products Association published a road map to carbon negative concrete using levers such as:
Seratech spinoff from Imperial College research, decarbonising cement and concrete production using alternative cementitious materials made from mineralising CO2 from industrial processes or the atmosphere.
Major cement producers are bringing to market:
Calcined clay cements
Bio cements
Carbon sequestered concretes
Magnesium-based cements
Future will be more sophisticated with different concrete for different applications.
Improve built environment – use less stuff - ie land use, water use, biodiversity
Right material for right job. Use performance priority
Locality part of conversation – concrete uses local materials
Rarely use British timber in Britain
Materials work better together - Timber and concrete hybrid limit the impact of fire.
Advocates should join together for a regenerative built environment.
Timber is the new timber; concrete is the new concrete.
Open to the floor for questions
Where is the timber going to come from in the Global South?
- Brazil, Chile for CLT; Kenya
What steps are being taken to bring in low carbon concrete for global availability?
This can be an early win for the material.
I have heard that if we continue to build with concrete globally we will run out of the right kind of sand.
- I have heard of this and it depends where you are in the world. There needs to be more research into alternative sand.
- In south Chile I grew up in a timber house. All the houses are made of timber. In Britain all the houses are built in bricks (clay). Is it to do with risk adversity and Health and Safety?
The Great Fire of London still has long reaching influence on regulations and building techniques in the UK.
Do you think timber would be used for biodiversity? Not having a monoculture is more sustainable for long term forestry.
- In favour of biodiversity and forests. We could do a lot better in using resources better.
- Does the concrete industry need to threaten the market more?
In New York the concrete industry has taken out advertising space on billboards in Times Square.
The government is saying ‘lets support timber’ when masonry needs support. The population is sleepwalking into a decision.
– This issue is not London-centric. It applies to China and Bangladesh and elsewhere.
If we are trying to change the carbon footprint of the world, then it is better to have better concrete solutions to sell to the rest of the world.
– Concrete and timber are joined at the hip in that concrete is usually shaped by timber formwork. Is there any progress with this?
- Risk, cost and speed? How much do we value what the occupier wants?
– If timber longevity is 10% that of concrete, then Norwegian churches are the exception. They have lasted 100s of years. In the context of time will timber last as long as concrete?
Georgian houses have remained a popular building type because of the flexibility of their timber interior walls that can be changed between generations while the stone exterior remains intact.
Can timber be as durable as concrete?
We are not talking about reinforced concrete, as this relies on steel and concrete and is relatively recent, in the same way CLT relies on wood and glue. We need better glue and using materials that we are good at. Should we not be using more fire-rated materials in construction?
We need to maintain buildings more.
We do not need to scrape materials from beautiful places. We need efficient, wise use.
Think not of just performance and capability. Think of need concrete, need low carbon concrete, can do better today.
Votes after the debate: Yes - 18 No - 21