Mass Timber Myths Dispelled

There are several prejudices about building in timber that lead to ungrounded misconceptions, hampering its mass adoption. Below the most obstinate timber myths are dispelled – for the complete story including full scientific background information, please refer to the book Tomorrow’s Timber to be ordered in the MaterialDistrict bookshop. Or check out my TED style talk about mass timber: https://www.youtube.com/watch?v=XygyLozl61o.

All images copyright MaterialDistrict

#1: There are not enough forests available in Europe to mass adopt timber as main construction material

Forests cover 37% of the land in Europe. Also, the European forestry sector is run very efficiently: at 4% of global forest area it produces 23% of all sawn timber worldwide, based on sustainable forest management. And there is still room for growth: the current European forests still have room to increase production capacity by 40-50%, while there is a lot of land available that is suitable for reforestation. If this is utilized, wood use for biomass energy production is reduced and increased cascading is applied, then every EU citizen can potentially live in a timber house or apartment by the end of this century.

Timber is a very suitable material for cascading in several applications before eventually being burned for energy production. In the meantime the tree should have grown back several times. 

#2: A timber building is not safe in case of fire

Exposed solid timber structures have very predictable behavior in fire because their outer layer chars at a constant rate while the structure underneath retains it full structural capacity. Taking this into account when dimensioning structural members, possibly combined with encapsulation in gypsum boards for example, can enable timber constructions to meet the most stringent fire safety requirements. 

Fire tests on glulam columns at SP Firetech arranged by Sweco Norway for the highest timber building worldwide, Mj?st?rnet showed that after 90 minutes of exposure to fire, the columns continued to char for a short period before eventually self-extinguishing (Photo: Sweco Norway). 

#3: A timber building will not last very long due to low durability

If timber is kept dry, it can have an endless technical lifespan (the oldest timber building in the world, the Horiyu-Ji Temple in Japan, was built in 607 AD). This also applies to interior bearing structures made from timber. When used outdoors, wood with high resistance to biological attacks can be specified, with modified wood technologies such as acetylated wood outperforming even abiotic materials in applications such as cladding and window frames. What’s more, throughout this time, the CO2 captured in the wood during growth will be locked for the lifetime of the building, which is about 5-10 times as high compared to CO2 released during production.  

Evolution from tall timber building from past (the Yingxian pagoda from 1056 still standing) to future

#4: A timber building is more expensive than conventional building structures

If designed with optimization of the prefabrication possibilities and the low weight of mass timber in mind, a timber building – in spite of the higher material costs – can cost the same as a conventional concrete building on project basis, even excluding monetization of potential carbon credits and benefits of building in timber related to health and open building principles. If these are taken into account along with increasing economies of scale, this could very well shift building economics in favor of mass timber in the near future. 

The 180 hotel rooms including sanitary units made from CLT of hotel Jakarta in Amsterdam, were fully prefabricated off-site and installed within 2 weeks. 

For complete references, background calculations and detailed explanations please refer to the international book Tomorrow’s Timber.

Other Mass Timber Myths that you want to have dispelled? Please email me at [email protected] and I will try to add to this article.