Mass Timber High Rises – Some of the Risk Considerations Within an Emerging Paradigm
The writer has watched the timber mass timber building movement gain momentum internationally for a number of years with considerable interest. Some venerated international experts have recently voiced certain concerns.
In a recently published article “Are mass-timber buildings a fire safety risk?”  authored by Nat Barker and published by Dezeen (architecture and design magazine), the author began with the observation that:-
“uncertainty among governments and insurers over whether mid-and high-rise timber buildings are safe in a fire remains a key obstacle to the greater adoption of engineered wood buildings.”
There was a further telling observation that:-
“no consensus has been reached across different building code jurisdictions about the safety limitations of building with wood (and more problematically), the rules vary wildly between countries.”
The said author cites Finland as having a “maximum height for a residential buildings with a load bearing timber structure and no sprinklers to be two storeys,” yet in Sweden there is no limit.
Said author added that some countries have relaxed their regulations to make building processes easier, but others such as the UK have made it harder. No doubt Grenfell has led to this ‘upping of the anti’.
The article went on to quote a number of fire engineering experts and some of their observations may well give policy makers pause. A common theme was the lack of uniform competencies.
The writer agrees with their diagnosis, but submits that that there may be more to do in this relatively new paradigm than an uplift in competencies and the Dezeen piece seems to allude to that. The mission would involve identifying best practice codes for this setting and then encouraging cross jurisdictional harmonisation and adoption of same. The greater good may be impeded if a siloed or jurisdictionally introspective approach is applied to code development in this space.
The Competency Imperative
Professor José Torero of University College London and fellow International Building Quality Centre board member was quoted in the Dezeen article as saying:
- “Timber can be perfectly safe if it’s done right.“
- “The problem is whether [building designers] are competent enough to be able to make a proper assessment, and that is a much, much more complicated question.“
- “Fire safety is not prioritised at all.. and nevertheless, we’re moving at a speed that is extraordinary. And to me… that is just entering a space where we are taking risks blindly.”
Joe Giddings of ‘Built by Nature’ in said article said about the matter:-
- “if we breed false confidence without competency becoming widespread, we’re playing a dangerous game. We shouldn’t play down the fire safety concerns.”
The same article observed that
- “only a small number of architects and engineers possess extensive knowledge of working with the material.”
Torero added that,
- “that needs to change fast… the height of the world’s tallest timber building has already more than doubled in the last decade and is soon is to hit 100 metres.”
- “There are no proper standards of competency when it comes to the design of mass-timber buildings… the potential consequences that you can have from poorly designed buildings can be catastrophic… I’m extremely concerned about existing buildings, as much as future buildings that are being built.”
“Competence is key here, especially with timber buildings and the current state of knowledge and research. Small low rise residential buildings of mass timber with small compartments are one challenge, but high rise office buildings with large open floor plates and substantial areas of timber unencapsulated is another whole challenge, for which we do not have the research and design/analyses methodologies. Yet we see them being designed and supported by fire safety and structural engineers in various countries with no idea of the risks that they are creating for themselves, whole design and construction teams, building owners and of course occupants and fire brigades. At least in NSW, government audit teams are starting to look at practitioner certification of designs at the design approval stage, but unless they have experienced fire safety engineers in their audit teams, they will probably not pick up incompetent practice. It will be very sad if we have to wait for a high rise Glulam/CLT mass timber building to have a major fire and burn before we have another public enquiry and things (might) change“Peter Johnson, Linkedin.
World renown and Melbourne based fire engineer Dr Jonathon Barnett of Basic Expert in the same commentary feed said:-
I agree with José Torero‘s assessment but have no idea how to effectively regulate it. Our university programs in fire engineering vary in context, rigour and quality to such an extent we cannot use a qualification as a fundamental basis of determining skills. Practice experience is again problematic as we have no universal agreement on how to measure its quality.
We need better education programmes but society is unwilling to pay.
We need a means of upskilling current practitioners, but they are too busy to do what’s needed.
We need fire brigades willing to hire and reward in house engineers and empower their voice; but there’s no willingness by current leadership to make appropriate investment.Dr Jonathan Barnett, Linkedin. 
A law reformers perspective
Though lacking the apposite technical qualifications to proffer technical opinion, I have extensive experience in the design and implementation of building regulation which has involved designing holistic regulations that manage and operationalise building codes and statutory deliverables.
So speaking as a past regulator and having regard to the consensus of venerated fire engineers that apposite competencies are critical, it then begs the question; how should one establish, create, and then implement a competency regime?
Also live to Dr Jonathon Barnett`s comment, “we need better education but society is unwilling to pay” the fact of the matter is that all governments may not be willing to pay; but pay they will need to if there is to be a government inspired collective resolve to uniformly uplift competency levels.
How should one establish, create, and then implement a competency regime?
The free marketers are of the opinion to leave matters such as the establishment of competency criteria to the market. However, the market may have very little interest in evolving uniform competency criteria particularly if it imposes an increased cost burden.
Others would say leave it to the professional associations as they are best equipped to know what the skill sets are.
The professionals may well be best equipped to formulate the skill sets, however the challenge for the professional association is establishing “right weight” qualification criteria absent the involvement of consumer representative bodies and the interaction of other professional bodies that populate the fire amelioration space. It is submitted that the competency criteria has to be such that it recognises the interrelationship, and to some degree interdependence, of other key actors as building involves an interaction of many professionals, contractors, and subcontractors. No profession operates in a vacuum when a building is constructed. This fact should not be overlooked in the design of appropriate curricula.
To achieve the “right weight” setting, it is submitted that there may need to be a coalition of symbiotic practitioners that operate in this paradigm, comprising: manufacturers, designers, constructors, and possibly mass timber application experts or ‘scientists’ (as it were) and approvers.
It is also submitted that this is best abetted by working in collaboration with government registration and accreditation bodies, for this is likely the best way to promulgate and proliferate the competency criteria for the ‘standards’ Torero is referring to.
The challenge as Dr Barnett so pertinently puts it, is how does one effectively regulate?
It is submitted that there should be the regulation of well thought out entry level competencies and the accreditation of those that achieve the competencies. The writer is not confident that absent regulatory intervention, it will be possible to compel the adoption of competency standards that the experts are advocating. Jurisdictions like New Zealand, the Australian state of Victoria and the Northern Territory have government controlled registration regimes for key actors.
If ‘on point’ competency accreditation were to occur, it would also be possible to migrate those with suitably accredited skills sets to other jurisdictions that have mutual recognition competency legislation. (Reading between the lines there seems to be a finite level of expertise at this time). Were this to occur, the jurisdictions lacking in skill availability could avail themselves of off shore accredited experts.
How, what, and who to regulate?
A lack of uniform competencies cross jurisdictionally can in this writer’s submission, only be resolved if there is uniform regulation or standards that can be promulgated same.
Sometimes this entails the registration of new classes or sub classes of professional registrants. Case on point, until the Building Act 1993 was promulgated in Victoria, there had existed a loose fellowship of building draftspersons and there had been no uniform qualification or experience criteria. Some draftspersons came off the tools, for some the skill evolved organically; so the skills set lacked uniformity and the competencies were variable.
When the said Act promulgated a requirement for draftspersons to be registered, a viable and sustainable profession was created and the regulations promulgated a qualification criteria. It was “greenfields,” but 35 years later we now have a mature and moreover an insurable profession, where professionals are all required by law to carry compulsory professional indemnity cover. (Victoria registers engineers, builders, building surveyors, building inspectors, and quantity surveyors).
After the leaky condo crise in Canada, there emerged a subset profession of building envelope specialists or “building envelope engineers.” These professionals checked façade integrity to ensure that the outer layers were resilient to the vagaries of climate and tempest. It follows that there is plenty of precedent for the establishment of new professionals subsets.
The writer observed that the University of Sydney has a course in ‘Building Envelope and Adaptive Engineering,’ where students are exposed to available building envelope technologies and their engineering technologies’.  It is submitted that a course titled ‘Mass Timber High Rise and Adaptive Engineering’ may be in order in a university. But it would probably need to be an international online course to generate a critical mass of students.
Admittedly, the below mentioned professions are more established, but the question remains do they have the bespoke skill sets that are required to marry up with a relatively new technology? The said experts suggest not always, hence the mileage in establishing a bespoke course.
By way of reiteration, it is submitted that the competency criteria should be developed in conjunction with peak bodies, be they industry, consumer, and academic institutions, and it is a given that there would need to be a willingness on the part of government to embrace the challenge of consultation, honing and ultimately promulgating apposite qualification criteria.
There would also need to be an identification of the professions that would need to be brought into the competency fold. At first blush having read said piece, the professions that come to mind are:
- Designers per sea
- Engineers (with regards to engineers in particular structural and fire engineering).
But does it stop there?
What about builders and certain classes of subcontractors? For it is one thing to design, but designers don’t build, the actual building is undertaken by the head contractor and certain sub-contractors like truss erectors, carpenters, and frame constructors.
Then who does the ‘as-built’ sign off? The designer? The designer and the building official together? Or does the building official have the ability to delegate the sign off inspection to an accredited individual with the relevant competency criteria?
The need for best practice codification of mass timber high rise construction regulations
Danny Hopkin of OFR Consultants stated in the Dezeen piece:
“It’s definitely possible to build timber buildings that meet an adequate level of safety, but you cannot build anything you want without constraints… you have to address the specific hazards that those buildings present.”
As an aside, the writer has always been intrigued by the phenomena of mass timber high rise construction in light of the compellingly obvious fact that wood is a fuel. To put it simplistically one can purchase fire wood from local vendors to stoke the winter living room fire. One does not stoke the fire with concrete debris or steel components. The writer was thus reassured that this rather axiomatic fact was mentioned in the said article in the statement “unlike in a steel or concrete building, in a timber building the structure itself is a potential source of fuel.”
It is this self-evident fact that may require a bespoke approach to the codified regulation that governs this paradigm. The regulation of a construction genre where the predominant material can be the fuel, alternatively the codified regulations could be located in a generic high consequence building classification that governs emerging technology.
The Building Codes, are they sufficiently tailored and do they need to adapt?
How up to date and ‘on point’ are the particular codes and what is the assessment criteria which one measures against in the codes? The following types of issues should come into consideration for code writers:
- Mass timber building height limits.
- Whether there is any place for non-prescriptive, flexible performance based codified regulations.
- Whether the codes must contain a highly prescriptive deemed to satisfy provision that places an embargo on a non-prescriptive design and construct methodology.
- Product suitability and product accreditation.
- Wooden density criteria.
- Suitable fire resistant wood “species” as it were.
- Mass timber building façade and related questions such as use of material that is impervious to water penetration and fire ingress.
- Is there a sprinkler imperative ie: is there a need for a provision that dictates that one can only build in this genre if sprinklers are made mandatory? I would have thought that this is another given.
One of the IBQC Board members Ontario based Michael De Lint who like the writer has done a lot of consultant advisory work for the World Bank, volunteered some thoughts that are instructive in reinforcing the writers contention that much more is in play than the lifting of competency imperative. I will quote from him directly:-
“What is the height threshold of high-rise? In Toronto it is a building over 11 stories – those lower than (between let`s say 4 stories and 11) are called mid-rise. The Ontario Building Code (aligning on this point with recent National Building Code changes) now allows for mass timber buildings up to and including 12 stories.
USA’s “International” Building Code, IBC, allows mass timber up to 18 stories. Some mass timber buildings are already taller than 12 stories (examples include mass timber buildings in Vancouver, Minneapolis, Norway, Switzerland, Austria and also in Perth, Melbourne etc, in Australia).
Having been involved in the development of code provisions for 6 storey wood frame buildings and a guideline for tall mass timber buildings (prior to the recent Code change), I can say from first-hand experience that both projects involve extensive input from the fire service along with building engineers etc.
In the case of the 6 storey provisions included in the 2012 Ontario Building Code, there was extensive discussion of matters such as: fire safety of building exits (two emergency exits are required in Ontario versus 1 in UK high-rises at the time of the Grenfell building’s construction); automatic ‘sprinklering’; combustion resistance of exterior cladding; building height limits to ensure fire service access; provisions related to concealed spaces, firestops etc; fire separations; ‘sprinklering’ of balconies; etc.
The intent was to ensure that wood frame buildings were no less safe than 6 storey buildings using other structural materials. In the case of more recent Ontario Building Code provisions allowing 12 storey mass timber buildings, based on NBC provisions, the approach was no less rigorous.“Michael De Lint.
Michael’s views lend weight to the need for a holistic and highly consultative approach to be deployed in code development. Particular regard is had to his stating:-
“That extensive interaction occurred with fire services and engineers and the use of the word etc meant apposite actors were consulted too.”
That which were considered to be some of the vital elements:
- automatic ‘sprinklering’;
- combustion resistance of exterior cladding;
- building height limits to ensure fire service access;
- provisions related to concealed spaces;
- firestops etc, fire separations;
- ‘sprinklering’ of balconies; etc.
Note Michael’s statement (and it would be worth of closing line):
“The intent was to ensure that wood frame buildings were no less safe than 6 storey buildings using other structural materials.”
Note the safety imperative: although it seems obvious it is this writer’s submission the paramount imperative.
The writer considers that these key considerations are all in play and those with appropriate expertise will have critically important contributions to make in the shaping of policy narrative. Further too, for fear of exhausting this plea, experts must be allowed to interact with policy mandarins and code writers, for without their interaction the goal of good practice bespoke codes will remain elusive.
Long term sustainability and resilience of product
A related consideration is to know how mass timber resilience interacts with long term exposure to weather interactions and events in particular wind, water, heat, cold, and tempest. This is a question for the technical experts and possibly scientists who may have views on whether there could be shrinkage, expansion, structural torsion, timber contraction, or bending and movement and if so how would this impact upon the long term fire resilience of a mass timber high rise?
The question of whether mass timber high rise is suitable for heightened seismic activity zones should also be put. Lacking technically qualified expertise in this area I can only ask the question. But I think it is a question that needs to be asked, particularly from someone who was born in a country sometimes euphemistically called the ‘Shaky Isles.’
It seemed a good idea at the time
The 1990’s Leaky Building Crises in NZ had much to do with laissez faire building codes that permitted construction of buildings with untreated pine. Once the building was exposed to water ingress and inclement weather the pine expanded and corroded structural integrity and façade. This culminated in billions of dollars of remediation and for many years the Auckland sky line was punctuated or pockmarked if you will, with ‘leakies’ covered with tarpaulins.
When the “de-regulationary” euphoria occurred in NZ in the mid-nineties coinciding with the promulgation of a performance-based building code, it seemed to be ‘a good idea at the time’.
This writer was on record as being nervous about the ‘de-regulationary’ evangelism and voiced that nervousness in a piece that was published in CIB magazine that was rather pessimistic. He was perceived, and in some quarters angrily dismissed, as a naysayer at the time and his scepticism was not well received by the then New Zealand Building Industry Authority.
Yet his ‘reading of the tea leaves’ was in fact underwhelming in it’s pessimism, as the magnitude of the consequences of this deregulatory push was underestimated by the writer. By the mid-nineties a national industry and consumer crises was realised to be unfolding which ultimately cost the country well in excess of eleven billion dollars of remediation.
The lessons of the past must be heeded as they are instructive
Grenfell, and the NZ and Canadian leaky building crises lessons should be taken as instructive.
Some of the key ‘take outs’ are:-
- New construction paradigms that have the potential to affect the well-being (and most importantly the safety) of the citizen have to be very, very carefully thought through. The excitement of the ‘new’ has to be tempered with the ultimate leveller: ie the paramount overrider must be the safety of one’s fellow citizen.
- So reminiscent of the chess player, the policy architects need to consider the impacts of the first move or foray into an emerging paradigm upon down the line scenarios. For the wrong or ill-considered move can be fatal down the line.
- The predictions must be conservative, astute, and devoid of any wishful thinking, they also have to factor in the possibility of worst case scenarios and how best to codify in a manner that ensures that such scenarios through good code writing never see the light of day.
- New construction paradigms of the above persuasion should not evolve without the close interaction with the apposite government agencies.
- For fear of being accused of using a well-worn cliché; “holistic and whole system approaches” need to be applied. Somewhat like a well-engineered Swiss watch where all of the key actors, agencies, manufacturers, and apposite elements operate in methodical unison.
- This may mean that there are regulated subset ecologies as it were, the subset of best practice regulatory code ecology for mass timber high rise construction, where there is a bespoke set of holistic regulation curated for this paradigm.
- This will involve an interaction with the building code and the administrative provisions that operationalise the ecology.
- Once the regulations are promulgated they must be operationalised and Treasury must allocate sufficient funds to underwrite enforcement and compliance.
Mass timber high rise is a relatively new paradigm, one where uptake is variable and key codified criteria and thresholds are lacking in uniformity.
Some international experts are nervous and have highlighted a lack of uniformity in ‘on point’ building code provisions and a lack of sound competencies.
There is agreement that mass timber high rises can be built safely, provided risk is understood, factored in to design, and assessed by those competent.
This lack of uniformity can only be resolved if there is more pan-jurisdictional interaction between governments, policy mandarins, and fire engineering experts. If this does not occur Nat Barker`s observation that “no consensus has been reached across different building code jurisdictions about the safety limitations of building with wood and (more problematically) the rules vary wildly between countries” will prevail as the status quo.
As the area is at a relatively early stage of its journey, the accreditation of bespoke competencies will lend itself to skill portability. Skill portability will be necessary if there is no critical mass of expertise in jurisdictions new to the paradigm.
Having said that, competent actors operate most effectively if best practice codes are harmonised and code writers adopt uniformly best practice criteria. This provides same with the ability to measure compliance with a common and rigorously developed code criteria.
It thus follows that mass timber high-rise constructs may warrant their codified own risk classification.
This will obviously require a definition of that which constitutes a high rise in this setting; be it height, number of floors, number of occupants or all of the above. This is a matter for fire engineers and mass timber scientists to advise on and code writers should ‘absolutely ensure’ that their advice is sought before pen is put to paper.
This opinion piece is written by Adjunct Professor Kim Lovegrove MSE, RML and his views are those of his own and are not representative of any other body or party.
This article is not legal advice and discusses it’s topic in only general terms. Should you be in need of legal advice, please contact a construction law firm.
 Nat Barker, ‘Are Mass-Timber Buildings a Fire Safety Risk?’ Dezeen (Article, 22/03/2023) <https://www.dezeen.com/2023/03/22/mass-timber-fire-safety-timber-revolution/>.
 www.sydney.edu.au, 2023. ‘CIVL5535: Building Envelope and Adaptive Engineering'<https://www.sydney.edu.au/units/CIVL5535>.