ImmenselyMental
Active Member
From this morning:
- Thread starter ProjectEnd
- Start date
northyorker1
New Member
Honest question: why couldn't they just build it with an all steel structure? Can't imagine using wood saved them any material costs here.
ProjectEnd
Superstar
The whole point was to do it in wood. It's not about 'saving material costs', it's a demonstration / 'learning' building for future construction tech.
northyorker1
New Member
Ok, but what are the benefits of using (this type of) wood over steel or concrete (in high rise construction)?
MAC
New Member
The benefits are numerous....
Environmental - mass timber captures and stores a massive amounts of embodied carbon during growing cycles, and holds it through production and is therefore not an emitter. It is considerably less polluting than production of steel or concrete. Looking at global CO2 emissions - 7% comes from the production of steel and 8% from the production of concrete, annually. Mass Timber is renewable without causing further polluting byproducts. As long as the wood products used to create mass timber are sustainably managed, as they are in Canada, it does not contribute to degradation of existing forests. The wood is not old growth, but engineered softwoods like Douglas Fir or spruce-pine mix. There is also a reduction in construction waste, reuse/renewability of off-cuts.
(Some steel will always be required for modern mass timber construction ie. connections....similarly, concrete will always be needed for foundations...at least at this time)
Time - Speeds up construction time and sequence of erection, allowing for faster progress in enclosing structures...means less waste and need for additional measures during constuction...ie fossil fuel or electric heating (which is common).
Fire resistance - Little know fact that mass timber has greater fire resistance than steel. Timber creates a char layer on the outside that protects itself and does not alter its strength capabilities. It is however, still subject to the same fire protection requirements under building codes as steel and concrete.
Fabrication - Precision of fabrication is higher, almost all work is done offsite, allowing for greater control and use of computer operated CNC machines. Fabrication times are quicker than traditional, modern materials. Additional steel connection plates are fabricated offsite and typically almost no welding is needed.
History - Significant historical proof demonstrating the use and effectiveness of mass timber construction. There are surviving timber structures that are 1000's to 10,000 year old, many of which are still in use.
Appearance - Timber is warm and pleasing to occupants. Can be finished in numerous ways and colours, refinished easily and a major factor in biophilic design principals.
Costs - Its still early days, but once production and stronger supply chains are developed, mass timber will up to be 20% cheaper than steel/concrete. Currently, the savings are in shorter construction schedules.
Labour - Less labour or smaller crews required to perform the work, meaning cheaper costs for clients.
The purpose of mass timber is not to replace steel or concrete, but to offset and minimize its use. Check out for further info https://academic.daniels.utoronto.ca/masstimberinstitute/
MAC
New Member
The start of the cantilevered south portion of the building that will run 11 floors, first time in mass timber construction.
UtakataNoAnnex
Senior Member
The big downside I guess is that they need harvested trees in order for this to work. I don't want to say one person's environmentally sound tower is another's clear cut in a virgin forest...
...but I do believe one must be as environmentally responsible in the building of such as the building itself. Or it seems a bit pointless in going with this alternative from that narrative.
...but I do believe one must be as environmentally responsible in the building of such as the building itself. Or it seems a bit pointless in going with this alternative from that narrative.
MAC
New Member
Harvesting of wood for mass timber is not done from virgin or old growth forests. It is sourced from the same tree farms that produce soft wood lumber for the building industry...ie. stud framing for the housing.
Also, the harvesting of farmed trees is far less environmentally damaging than either steel or concrete that require the mining of natural resources....causes pollution, the refining of resources...more pollution and then repurposing of said material which caused additional pollution. Also, farmed timber naturally embodies and stores previous carbon emissions, which is a significant win that no other building product can do.
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UtakataNoAnnex
Senior Member
Ryan J
New Member
Looking at the pictures, I'm hoping it's not just wood superficially wrapped around steel beams. Is it? It would be a shame if the wood is just for show.
Or are we just seeing two steel framed truss "cores" going up the height of the building, surrounded by fully wood-beam structures around them?
Or are we just seeing two steel framed truss "cores" going up the height of the building, surrounded by fully wood-beam structures around them?
ProjectEnd
Superstar
The core is steel and the rest is wood.
Northern Light
Superstar
@UtakataNoAnnex asks broadly about how sustainable mass timber / CLT really is.....
So, if we're honest, the jury on that is still out.
The benefits outlined by @MAC are broadly accurate, but a variety other factors come into play.
Some seem to work out, in theory........but we don't have the time/experience to show that they do, yet.
While others raise serious questions.
This is a somewhat dated report from Yale, looking at the sector in 2019:
e360.yale.edu
A somewhat more recent report from 2022/updated 2024 from a different source, can be found here:
greenbuildingcanada.ca
I think both read as reasonably balanced. There are clear benefits, there are more problematic bits and some unknowns.
Further study remains necessary.
****
The electric car is not an unreasonable analogy.
The benefits of not burning fossil fuels are clear enough.....
But the electricity running an electric car is only as clean as the grid that powers it. (ie. much of China's power grid is coal powered, so not very green, if you're charging your car w/the product of a coal power plant....the advantages
are more....dubious).
Additionally, one must weight the environmental costs of mineral extraction, notably Lithium, but many other critical minerals as well. There's also the matter of disposing of spent batteries. (highly toxic).
One of the unknowns of Mass Timber that is a big factor here is how it will be disposed of when the time for demolition comes. Its largely too early to answer this question. But, simply, if you eradicate the timbers through conventional demolition or industrial chipping, the carbon-storage value is wiped out.
So its all be a bit more nuanced that most people are comfortable with.
Its very much worth exploring the tech; but it is not yet a proven panacea.
So, if we're honest, the jury on that is still out.
The benefits outlined by @MAC are broadly accurate, but a variety other factors come into play.
Some seem to work out, in theory........but we don't have the time/experience to show that they do, yet.
While others raise serious questions.
This is a somewhat dated report from Yale, looking at the sector in 2019:
As Mass Timber Takes Off, How Green Is This New Building Material?
Mass timber construction is on the rise, with advocates saying it could revolutionize the building industry and be part of a climate change solution. But some are questioning whether the logging and manufacturing required to produce the new material outweigh any benefits.
e360.yale.edu
A somewhat more recent report from 2022/updated 2024 from a different source, can be found here:
Cross Laminated Timber Pros and Cons | Green Building Canada
Cross laminated timber construction shows great promise for the green building industry. Learn about the pros and cons of this material here.
greenbuildingcanada.ca
I think both read as reasonably balanced. There are clear benefits, there are more problematic bits and some unknowns.
Further study remains necessary.
****
The electric car is not an unreasonable analogy.
The benefits of not burning fossil fuels are clear enough.....
But the electricity running an electric car is only as clean as the grid that powers it. (ie. much of China's power grid is coal powered, so not very green, if you're charging your car w/the product of a coal power plant....the advantages
are more....dubious).
Additionally, one must weight the environmental costs of mineral extraction, notably Lithium, but many other critical minerals as well. There's also the matter of disposing of spent batteries. (highly toxic).
One of the unknowns of Mass Timber that is a big factor here is how it will be disposed of when the time for demolition comes. Its largely too early to answer this question. But, simply, if you eradicate the timbers through conventional demolition or industrial chipping, the carbon-storage value is wiped out.
So its all be a bit more nuanced that most people are comfortable with.
Its very much worth exploring the tech; but it is not yet a proven panacea.
UtakataNoAnnex
Senior Member
To be clear, I do not want to discourage our pursuit for more environmentally sound products, developments and services. We owe it to ourselves and our planet to push forward here. Nor do I want this to feed some conservative trolls' "I told you so" moment...as that's entirely missing the point and is unhelpful. They want to see the planet burn anyways...
...that all said, we still have to be very careful and holistic in how we approach in saving the environment here while trying to sustain ourselves, as our cures can end up being worse than the issues we trying to resolve. It's an important distinction we have to recognize. And this tower is good starting place to address this among others, IMO.
...that all said, we still have to be very careful and holistic in how we approach in saving the environment here while trying to sustain ourselves, as our cures can end up being worse than the issues we trying to resolve. It's an important distinction we have to recognize. And this tower is good starting place to address this among others, IMO.
MAC
New Member
No, it's fully mass timber. The exit stair cores are steel as a requirement by Toronto Fire, due to the timeline that the building permit was submitted. If it were now, that requirement would not have been required.
Any steel used is due to the challenges have having a cantilever with mass timber...this is still a bit of a challenge out of mass timber, but the cantilever is required to make the floor plate viable for use.
MAC
New Member
Yes, only the exit stairs. The elevator cores are timber. The steel that is visible is a vertical truss that transfers the cantilever loads to the foundations.