Slow insertion of timber construction systems in the market of multi-story buildings and the construction sector is generally the result of what we call 'structural inertia’ (Figure 1). It means that despite the removal of regulatory barriers and the existence of technical solutions, the system leans towards maintaining the status quo as a result of long-established traditions and practices, investment and technological lock-ins, knowledge gaps, among other bottlenecks such as the risks involved in developing a new industry or the general reluctancy of any society to change. We illustrate this web of bottlenecks in Figure 1 and describe them as follows. 

1. Path dependency: an established system normally resists change, not simply because of society’s or firms’ ‘fear of change’ or because they are ‘comfortable’ where they are. Resistance to change emerges from the way all components in a system have been positioned in a complex web of intertwined and co-dependent actors, where one ‘piece of the puzzle’ is shaped to fit the whole, and thus cannot easily break off to fit a new puzzle. In this way, all components of the construction sector, including material and service suppliers, construction companies, real estate firms and all players along supply chains have welded a strong mutually dependent relation, which is glued together by a regulatory system and policy framework that is designed to determine the boundaries of the known system. All this makes it difficult to wedge between these links.  

2. Social institutions: structural inertia is also the result of society’s resistance to change due to the well-formed norms or ‘ways-to-do-things’, which is built over time by tradition, experience, and accumulated knowledge of what works, and what does not. In this way, wood as a material is commonly perceived as a fire hazard, that it risks moulding, or that it is lower quality than other seemingly more robust materials such as cement and steel. Resistance comes also from the practical implications on household economies, or disruptions in regular life, as well as mistrust to what change implies generally. For instance, despite the enormous benefits for living conditions, the programme for mass renovations of old soviet buildings in Estonia does receive some resistance from certain members of society.  

3. Regulations: although multi-storey buildings in timber are now unrestricted, there remains some barriers, mainly related to fire safety regulations. Moreover, municipal planning systems and zoning regulations are slower to change. They are generally designed to meet the technical requirements of standard construction systems, for instance by determining the height of buildings in a street or neighbourhood. Yet, a building made using mass timber frames will automatically be taller than a concrete building of the same number of floors.  Another barrier is that public procurement rules generally favour the cheapest proposal rather than, the most environmentally friendly option. In Sweden, what was initially a benefit to timber construction, the ‘material neutrality’ principle, has to some extent also become a limitation as municipalities cannot demand the use of timber in publicly procured projects.  

4. Knowledge gap: there is a general vacuum of knowledge about timber construction in the whole system, from structural engineers, developers, builders, architects, to material scientists and academics, all the way to educators, regulators, real estate firms, banks, and insurance companies. In addition, there are insufficient data about the performance of existing wood buildings or the state of the built stock to inform new projects, as well as reducing uncertainties and the perceived risks. For instance, 40% of registered buildings in Latvia have unclassified intended use. More comprehensive data collection would be essential for strategic policy design, such as the programme of serial renovations in Estonia.  

5. Price/costs: there are high costs related to acquiring knowledge and training, testing, piloting, establishing new practices, scaling up industrial capacity (including huge investments in infrastructure and equipment). In early phases, new products i.e., timber buildings are generally more expensive than conventional concrete buildings. There are also costs in establishing new business ties and building a new network of suppliers and clients. Finally, there may be higher costs of interest loans and insurance premiums based on perceived or expected risks linked to innovations. Often, the lack of accumulated experience results in banks hesitation to give loans for timber buildings or for renovations as they are unable to assess the risks.