02x06 - Timber Skyscraper

[bunniefuu]

[taut mellow music]

Put simply, the way we build

our towns and cities needs to change.

The construction and
operation of current buildings

accounts for 40% of the
world's energy consumption,

and approximately 1/3 of
greenhouse gas emissions.

But could one of the
oldest building materials

known to humankind form
part of a modern solution

for our buildings and cities of the future?

[bright techno music]

A global technological
revolution is underway.

We think in the next 10 years,

you'll see more innovation

than we've seen in the past 15.

Driven by passionate, dedicated individuals

intent on shaping a new world.

I wanna create something new.

I want to create something that gives me

the sense of faith in new life.

This is why I'm here.

A greener world.

This is the last call to action

that we have to develop the solutions

that are protecting our planet.

A better world.

I have a family, and when I think about

the life I want them to have

and their children to have,

I want them to experience the world

where they can travel
and live without worry.

And that gets me been going every day.

Together, they are pushing engineering

to its limits.

Human creativity is the
most tremendous power.

And if you set a target,

things that you never thought possible,

become possible.

Creating extraordinary machines

that can help the planet
and humankind in the future.

[bright techno music]

[mellow music]

Architect and historian,
Professor Maxwell Hutchinson,

has not only been designing
buildings for half a century.

He's also been involved
in their conservation,

some of which date back
over a thousand years.

He's one of a growing number of people

within the construction industry

who believes that the huge carbon footprint

associated with our current
use of building materials

to just concrete is unsustainable.

There is general consensus
that we need to change

the materials we use in
building all of our buildings.

There's a huge amount of embodied energy,

that is to say, the energy that goes

into making the material,
transporting the material,

and putting it into position.

And Portland cement,

which is the principal
ingredient of concrete,

is incredibly-energy intensive.

It is estimated that
annual cement production

currently accounts for around


And what the cement is
mixed with to create concrete,

further compounds the ecological damage.

Every year, the construction industry

uses 50 billion tons of sand.

That's enough sand to
cover the United Kingdom.

And the problem is,

that the world is running
out of the right type of sand.

The wind-worn granules found in deserts

are far too smooth to bind
together to form stable concrete.

So acute is the shortage
that all over the world,

riverbeds, beaches, forests, and estuaries

are being stripped bare,

often by organized criminal gangs

operating on a vast scale,

with lethal consequences
for those who oppose them.

But what if we could find a sustainable way

of using an extraordinary
building material,

one that as part of its production process

actually absorbs carbon?

Well, the good news is we can.

[pensive music]

[bright music]

In downtown Milwaukee,

we might be seeing a glimpse of the future.

Amongst much media attention,

a groundbreaking ceremony is underway.

Normally, this takes place before

even a shovel breaks the earth,

but this is no ordinary build.

Although concrete
foundations, parking floors,

and lift shafts have been completed,

for those involved in this project,

it's all about what comes next.

If it's not been apparent,

literally, words cannot describe

the excitement I feel
about being here today.

Property developer Tim Gokhman

never intended to make history.

He just wanted to make a building

that people wanted to live in.

Standing 284 feet tall, its 25 stories

will house 259 luxury apartments,

a pool with retractable walls,

even an outside cinema.

When completed, it will be

the tallest timber building in the world.

And many believe, it'll point the way

for how we should be
constructing our cities in the future.

It's name, Ascent.

I remember a structural
engineer, John Peronto,

said this building would change the way

that codes are written.

John, I don't know where you are.

I thought you were being dramatic.

I was wrong.

He probably heard the quote.

I did say when we started this,

if we get it built, it
will change the code.

It will.

[mellow music]

To be able to create a building

that will change the codes and rules

that govern tall timber
buildings here in Milwaukee

has required the support and cooperation

of some of the finest engineering talent

from around the world,

the city planning authorities,

the fire department, even
the US Forest Service.

You know, it seems like

when you're doing something really special

and you believe in it,
things just come together.

What inspired Tim Gokhman

was seeing a project for
an 80-story concept design

by architects Perkins and
Will, Cambridge University,

and engineers Thornton Tomasetti.

These projects that we
do internally in the industry,

these are really what spur innovation.

And the aim of this particular project

was to see how far you could push

the boundaries of timber construction

with the innovative use of
prefabricated components.

They include Glued Laminated Timber beams

known as glulam beams,

and panels made from
Cross-Laminated Timber layers

called CLT.

Collectively, they are known
in the industry as mass timber.

It seemed like something out of the future.

It was unbelievable,

not just the fact that you
could do this to such a height,

but that all the wood was exposed inside.

And I sent it to the rest
of the development team,

our architect, et cetera, and
we asked them the question of,

"Can we build a high-rise out of timber?"

I think Jason's been waiting for years

for a developer foolish
enough to ask that question.

So he was pretty excited.

I would say a combination of excitement

with a healthy dose of fear tucked on,

because it had never been done.

Excitement and nervousness [laughs].

I mean, that it's one thing
to do research projects,

another thing then to
actually bring it to reality,

I would say River Beech
was more of a research project

than what you would call even
a concept study for a project.

But if it could be achieved,

the potential benefits are huge.

Some estimates suggest

prefabricated mass timber construction

is 25% faster than a traditional build,

reduces construction traffic by up to 90%,

and cuts the people required
onsite by three quarters.

It is such a pre-engineered system

that is done to a detail level

that is not typically done
for both steel or concrete.

Leads it to be much more complex.

The level of coordination that
we were required to manage

was like nothing we've ever seen before,

because we digitally built this building

down to the last group,

so it's been really, really eye-opening.

And this is the way that buildings

are going to be put together in the future.

Because of the concrete
base and elevator shafts,

Ascent is what is
technically known as a hybrid,

with timber making up 70% of the structure.

Although high-rise hybrids have been built

in Europe and Canada,
this is the first time

that anything even close to this

has been attempted in the US.

In general, I mean the mass timber frame

supports the weight of the floor.

So basically, everything
you're standing on in a wind,

like condition where you have
wind blowing on the building,

or you have, say, a seismic event,

that is resisted by the concrete cores.

A really good example
of the level of coordination

that had to happen for
this building to be built

is driven by the fact that
as the building goes up,

the timber structure
gets smaller and smaller

because it's carrying less gravity load.

However, the number of screws

attaching the members stays the same.

And so literally, near
the top of the building,

we were running out of space in the wood

for the screws to not
clash with each other.

And so, the amount of
coordination that it took

to make sure that the connections

were properly designed and free of conflict

was hundreds and hundreds of man-hours

by three or four different companies.

There are a bunch of theories as to,

is it going to build faster?

Is it going to be as precise

as you believe it's
going to be in the models

and as others are telling
you it's going to be?

Yes, it was all theory.

[bright music]

Most developers wouldn't have the grit

to really push on and
do a project of this type.

It's one thing to do something new,

it's another thing to be the first.

It's probably not something

a rational person's gonna take on.

We didn't realize how
challenging it was going to be.

And I think you need that for innovation.

[bright music]

Designing such an imposing wooden structure

is one thing, but to
bring the designs to life,

you need to find people who can build it,

but who do you need?

The materials obviously
points to carpenters.

However, the building's size and structure

requires the expertise of iron workers

who became synonymous with the skyscraper

in the first part of the 20th century.

For contractor C.D. Smith,

putting this team together meant

consulting with workers and unions

to create a new way for
these established trades

to combine their skill sets.

It doesn't matter if you're a carpenter,

iron worker or, you know,
an office guy like I am,

we all can have our opinions and thoughts

and maybe it's the right
move, maybe it's not,

but everyone does a
good job of communicating,

and everyone wants
to get to that finish line

as quick, as safe, and as
cost-effective as possible.

They call it a joint venture.

So basically, everybody
does a little bit of everything,

regardless of what union you are a part of.

There's a lot of first times,
a lot of people coming,

introducing different
ideas and different methods

that we're gonna adapt on the fly.

[mellow music]

Beautiful.

Normally, we set up a rebar and a pan

and you pour a column.

And then you build a
deck and you pour a deck.

Concrete's like making cake.

Wood's completely different than concrete.

This is pretty, pretty neat.

If all goes according to plan,

one of the benefits of
this prefabricated design

will be the speed of its construction,

and the fact that it will require

an assembly team of
just 12 skilled workers.

However, the complexity of the challenge

should not be underestimated,
all very different

from pouring concrete into molds.

Even the most experienced of contractors

could be forgiven for
feeling a little daunted

by the sheer scale of the kit of parts

they're going to be working with.

Some are glued.

Some are straddled, it's wood on wood.

Some have a nice plate and there's bolts

that go through the timber.

And then you see the screw detail.

There's a million screws and fasteners

that hold the whole picture together.

It's a big jigsaw puzzle.

And it's a jigsaw puzzle

that requires the utmost precision.

Certain columns, in one face,

they'll be 16-inch screws that hold it,

and trying to fit them
all in within the spec.

Each screw has to be within an inch

and a quarter of each other,

and then not hitting another
screw as you're driving in.

Every screw has to go
in at the perfect angle,

to make sure that the
screw thread is in contact

with the right layer of laminated timber

making up the beams and slabs.

Yeah, I'm learning every day.

And when it comes to positioning

some of the columns,

which require quick-setting
epoxy resin glue,

there is an added pressure
of time before it sets.

And then when I say,
"Ready, it's rocket time,"

you got eight minutes to set it.

So I put, and then you got a plummet,

before the glue hardens, too.

Every column has to be precisely vertical

to fit with the floors that will follow.

You can set like 12 a day.

We wanna get faster than that.

We wanna do 24 a day.

For a building that has

so many prefabricated elements,

good transportation is going to be crucial.

But Project Manager Chris
Johansen is keenly aware

this is one area that
could easily wreak havoc

with their tight schedule.

There's a lot of concern with
the global shipping industry

with COVID, there's
labor shortages at ports,

there's labor shortages at rail yards,

all of that combines into us

just starting delivery
of over 400 containers.

And then there's the weather.

Yeah, it's gonna be comin'
very shortly [chuckles].

If timber skyscrapers are to become

a familiar part of our cities,

there is one key attribute in particular

that is essential they possess: endurance.

[soft mellow music]

For anyone who doubts the longevity

and durability of timber, look around me.



This is St. Andrew's Church in Greensted

in the county of Essex in Southern England,

the oldest timber building in Europe.

Like many churches, it has evolved

and been added to over the centuries,

but its thick timber walls
date back over 1,000 years,

to a time when England
was still ruled by Saxon kings.

The structure and shape
and form of timber buildings

was determined by the
trees that were available

to build the building.

Engineers have to be able to calculate

every part of a building.

The challenge that we face
is how to take this material

and give it the uniformity
and predictability

that we need in our modern buildings.

[mellow music]

The prefabricated timber structure

needed to create Ascent
is being produced in Austria.

Almost half of the entire
country is covered in forest,

occupying an area the size of Switzerland,

and with centuries of experience
and an eye to the future,

they are currently planting
more trees than they harvest.

The slower a tree grows,
the denser its ring pattern.

The higher the density,
the greater the strength.

It's for this reason that
timber from the Ascent project

has been selected from
forests at a higher altitude

where the annual growth is slower.

One company, KLH, is making the CLT panels,

whilst another, WIEHAG,

is making the glulam beams and columns.

Founded by a local
carpenter over 170 years ago,

WIEHAG has become
one of the world's leaders

in prefabricated timber structures.

In their warehouse,
timber destined for Ascent

is stacked, ready to
undergo a transformation

that will enable it to meet
the most stringent of criteria

determined by the engineers.

Just to give you a picture,

we produce for that building



but we have to pre-select 6,000 cubic meter

of sawn timber.

You see some of it in the background.

From this 6,000 cubic meters,

we selected only the best parts.

We don't throw the others away.

We just use it for other projects,

for let's say normal projects,

but the pre-selection
process was an extra mile

for the Ascent building, yeah, definitely.

Before the selection
process begins in earnest,

the sawn timber is kiln-dried

to reduce the moisture
content down to around 10%.

It then passes through a metal detector,

to ensure that there are
no small pieces of metal

that could damage the
expensive and complex machinery.

Then there is a laser scan who checks

how warped the timber is,

because it might be a bit warped.

And then we have an End Grain camera

to look on the annual growth ring,

because we have to
know if it's the right side

or the left side of the board.

And also how fast is the timber grown,

so the thickness of the annual growth ring.

The timber is then planed

and analyzed by X-ray to assess the density

and to look for any
resin pockets or cracks.

Once they pass selection,
every individual piece of timber

is given its own data file
containing all the information

gained from this analysis.

These pieces are known as lamella,

which comes from the
Latin word often applied

to armor, meaning thin plate.

Any weak parts of the
lamella can be cut out

and different sections joined together

using a process called finger jointing,

which greatly increases the surface area

under which glue can be applied.

And as part of quality
control, sample joints

are regularly tested to destruction.

The pressure needed to break the joint

is it equivalent to that generated

by the weight of 30 tons.

That's the same as
a fully-laden fire truck.

[mellow techno music]

The single lamella can be endless.

I mean, obviously, our
[indistinct] has some limit

and that limit is 50 meter,

and this thin lamella of roughly 40 mil

is very flexible.

So you can bend it to the
shape of your architecture.

With the carefully selected lamella

formed into the right lengths,

it can now be glued and compressed together

to make up the large beams and columns.

Once dried, these are precisely cut to size

using CNC machine.

It's only with the advent
of computer-aided design

that this scale of prefabricated
mass timber construction

has become possible.

Then you have, let's
say, your perfect shape.

And the last step is
still a bit of manual work.

After a few cosmetic finishing touches,

the steel jointing elements are added.

Every detail is considered
during the manufacturing process,

right down to the loading
of the shipping containers.

The sequencing of loading is so complex

a special 3D load
planning software is used.

By loading the container,

we also think already on
the installation process.

So, what elements do the require first

and therefore, yeah, we place the elements

in the right order
already in the container.

[upbeat music]

Having left the factory,

the beams and columns begin
a 7,000-mile journey by sea

to Port Milwaukee on the
shores of Lake Michigan.

Here, they are stored until their contents

are needed onsite.

[upbeat music]

And when they are,
it's down to Jesse Miller

to ensure that they
make the final four miles

of their journey, safely and on time.

Every single load, I think we're somewhere

around 90 now, has been hauled by me.

And as long as I continue,

I should deliver the
whole wooden structure,

the whole building.

It's definitely a proud feeling.

I'm proud to be involved in this project.

[upbeat music]

You know, originally the plan was

to have material at the Port of Milwaukee

two to three to four weeks ahead of time,

and then it would be ready for us.

And with all of those with COVID,

Suez Canal, et cetera,

those dates were getting extended out

to where it was scheduling
things down to the date.

Load 91, here we go.

[upbeat music]

[mellow music]

Back onsite, and 11
weeks into the timber build,

things are really starting to take shape.

Well, you gotta look way up now [laughs].

So that's a big difference.

Handling the complexities of sourcing,

procuring, and managing
all the timber elements

is Taylor Cabot and
her team from Timberlab,

a mass timber design
and construction company.

Can you imagine standing
here in your living room,

being surrounded by this wood?

You know, it's gonna be a really rich,

warm environment for people.

Like, that view is just insane.

This is why people pay
the big bucks, right? [laughs]

There's absolutely no margin for air.

We have 1,863 pieces
and they're all unique.

One of these fell off
the side of the building.

We wouldn't have a
replacement for that piece.

We would be asking for a new
one to be made and sent to us.

It's extremely critical
that everybody is on board

with understanding that
these pieces are irreplaceable.

And in some ways, you can't
put a price tag on any of them.

We've been extremely
lucky, but I like to think

that a lot of that is,
you know, the hard work

and dedication of everybody

in having an amazing
crew to put it together.

Taylor is no stranger

to record-breaking timber buildings,

having worked on the iconic eight-story

Carbon12 building in Portland, Oregon.

When it was completed in 2018,

it was the tallest timber
building in America,

standing 85 feet tall.

[mellow strings music]

We were very proud of that,

and we just feed it a
couple days ago here on site.

Feels good to actually surpass it.

Somebody has to [laughs],
so might as well be me.

We're blowing it out
of the water, actually,

which is pretty exciting as well,

not to just eat it out with an extra floor.

We're looking at seven
days a floor right now.

On a really good week,
they've been able to do it in five.

They set all the beams
on one floor in one day.

This is over a third faster

than with a traditional build.

There would be no way to do that

in any other material.

Such is the work rate,

that on average, one beam or column

is lifted from the truck every 15 minutes,

and every single timber component

has to be assembled
with the utmost precision.

Figuring out how to bring
the pieces safely up to deck

and set them, two
tolerances of 16th of an inch,

really requires a extremely thoughtful crew

who understands that and has that skillset.

The most impressive thing is,

you give a guy a random task

that he's never done before,

and how quickly they can figure out,

"Oh, if I do this or that,

I'm gonna do it exponentially faster."

It took probably like three or four floors

before we kind of got it down pat.

[materials clattering]

What are we on, 16 now, 16th floor?

As far as what we've
learned on this project,

I think is gonna say a lot as far as

what's gonna start happening in the future.

I come home clean, so that's a good thing.

Life's likes that.

Yeah, it's fun.

Not like fishing, but it's fun.

We're here to make this
project go, and I think,

I personally think we're
knocking out of the park.

[mellow music]

As Ascent soars ever higher,

it's interesting to know that Milwaukee

is no stranger to
record-breaking buildings.

Just a few blocks away is the city hall.

When completed in 1895,

it was the world's tallest
building at 353 feet.

[mellow music]

In many ways, it's a
mirror of its new neighbor.

Its conventional structure
built around a steel frame

sits on wooden foundations made from

over two and half thousand
white pine timber piles.

Yeah, it is ironic,

the flip that you see right now

with the use of mass timber on city hall

versus how we're using it on Ascent.

But in some ways, you
know, it's very similar.

You know, we pushed technology pretty heavy

back then with city hall,

but we're also pushing technology

pretty hard right now
with the Ascent project.

[mellow music]

Today, we're obsessed with high buildings.

They define our cities,

but span, the space between walls,

is just as important.

If mass timber is to be adopted

on a much broader scale,

it needs to be capable of supporting

a wide range of structures

essential to our 21st
century infrastructure.

At the same time as Ascent is being built,

a huge mass timber
roof is under construction

as part of the ongoing renovation

at Portland International Airport.

For those involved in the
design of passenger terminals,

there is a sense that perhaps the wheel

has turned full circle.

When King's Cross railway station in London

was built in 1852, they
used a laminated timber roof.

It was 105-foot wide and 71-foot high.

It was one of the
engineering marvels of its time.

No roof like that had
ever been built before.

But there was a problem
because of the steam trains

underneath this remarkable roof.

The water vapor attacked the laminations

in the timber, so it had to go.

The material chosen to replace it

at the end of the 19th
century was wrought iron,

which had revolutionized
the world of engineering,

but would soon itself be usurped by steel.

If laminated timber was to have a future,

it needed to change.

[bright music]

Andrew Lawrence is a structural engineer

and timber specialist at Arup,

a company which is
renowned for its pioneering work

in the world of engineering
and construction.

The game changer is
having a really good glue.

It wants to be strong,

but also it wants to be waterproof.

And those waterproof glues

were not invented until the 1930s.

Right until then, we could

what we call laminate structures

by taking small planks of wood

and stacking them
side-by-side or above each other.

King's Cross station,
they're stacked horizontally,

but they're not joined.

They're not joined together.

So, it's like all the leaves of a book.

They can all slide over each
other when you bend the book.

But if you glue those planks together

with very good, strong, waterproof glue,

those leaves of a book become

like a thick sheet of cardboard.

So, that's what those glues give us.

We can essentially make
much larger members.

So if we had the ability to create new,

more resilient timber beams 90 years ago,

why haven't we seen
buildings like Ascent before?

One of the really exciting new developments

is what we call CLT,

actually stands for Cross Laminated Timber.

The explanation of it is in the name.

Wood is fibrous and it only
has strength in one direction.

And so we take those planks, those fibers,

and we lay those fibers in one direction.

And then in the next layer,

we lay the fibers at 90 degrees to that,

and the same again and again.

So we've made ourselves this
Cross Laminated Timber panel,

which has strength in two directions.

And we can glue those
together into very large panels.

These panels might be 16 meters long

and four or five meters wide.

Now, this might sound
an obvious thing to do,

but it was only first done in about 1998.

So, actually really recently,

and of course, it's taken time

for the manufacturing
capabilities to develop.

So that's only been available
to engineers and architects

as a cheap building
material for about 10 years.

So, if we've got these large panels,

I mean, that's a game changer.

With these CLT panels,
we can use that as the floor

or the wall of an entire building.

You can imagine it like a giant piece

of flat pack furniture,

made out of all these wooden panels.

And what we all know

from making a piece of flat pack furniture

is we can assemble that really fast.

And CLT panels have the added benefit

of being four times lighter than concrete.

Now, that can be hugely
important in construction.

So first of all, a quarter of the weight

means that you've got at least four

or five times less
truck deliveries to site.

Secondly, it means that we can save

on the cost of foundations,

and also because the wood is lighter,

perhaps we want to
build over a railway tunnel

or something like this.

Quite a lot of wooden
buildings I think about

have been built in locations

where we couldn't have
really built in other materials,

or we couldn't have
built such tall buildings

in other materials because
they'd have been heavier.

And of course, the
extension of that is that

if we want to add perhaps one
or two stories onto a building

then wood can often be a
light, light way of doing that.

One of the biggest hurdles

Ascent has had to overcome

isn't one of engineering,
but of perception.

Could a tall building really
be safe if there was a fire?

And there is one fire in particular

that occurred long before

there were proper building
codes to go on construction,

and has become synonymous
with timber buildings.

The Great Fire of London of 1666,

that started in a baker's
shop in Pudding Lane,

spread throughout these timber buildings

as far as the River Fleet.

After the flames of the fire had subsided,

to walk through the streets of London

would have been utterly remarkable,

because all the belongings
of people had gone,

the thatch on the roof had gone,

but the timber frames survived the flames.

[somber music]

This ability of large timber members

to withstand fire, is something

that would later be proved
on numerous occasions

in the large factories and
warehouses of the 19th century.

And it's quite interesting
that some of code work

and the code information
we still have today

is actually based on dimensions and sizes,

which came out of engineers
looking at those fires.

Because of their extensive experience

in this field, David Barber
and the team at Arup

were appointed as fire
engineers for Ascent.

One of the challenges they faced

was that the existing building codes

for tall buildings in Milwaukee

were based on traditional steel

and concrete construction methods.

To make the case for timber construction,

it was essential to work closely

with those we turn to,
should the worst happen.

Often some of the
really clever ideas we get

to how we can solve some issues

come from fire departments

and the experience they have.

We had a fantastic fire department

who were enthusiastic about it,

understood what was going on.

So, we want to have them involved,

especially where it is quite
innovative and quite different.

I was very pleased to be a part of it.

You know, it's great to
have the world's tallest

mass timber building
in the state of Wisconsin,

and more specifically
in Milwaukee in general.

I think it's a big win for the city.

And I think buildings of
Cross Laminated Timber,

mass timber are going to change skylines

in big cities forever.

With a fire,

what's inside a building
is every bit as important

as the material used for its construction.

The majority of your heat is going to come

from the contents inside the apartment.

You know, we look at our
consumables and our furniture.

Arup had already been
independently conducting

some groundbreaking research

into how mass timber buildings

react to internal fires.

We've been doing some large tests

on very large compartments.

We've exposed Cross Laminated Timber.

We've been carrying those out in France.

And as part of that,

the process has been to work out

how do fires react and change

in larger compartments and larger spaces.

The tests have been able to help quantify

to what extent exposed
timber in a modern building

will feed a fire once it's started.

In the same way that, you know,

we engineer for earthquakes and tornadoes

and high winds and high snow loads,

and all those sort of things,

as long as we know about it,

we can then safely engineer for it.

So, it's a matter of
understanding what the issue is,

understanding what the
data is, the sort of loads,

and the way that the
structure is gonna be impacted,

and then work out what are the mechanisms

and levers that we have to pull

to be able to design the structure

to withstand that type of fire

and that type of fire development.

Whilst the research has been invaluable,

it was still not enough

to instigate a change in building codes.

Because of the
unprecedented height of Ascent,

it would need to prove
that in the event of a fire,

it would have the same structural integrity

as a conventional skyscraper.

So we were absolutely
looking at sort of something,

which is a sort of breakthrough.

And to achieve that breakthrough,

the timber columns would
need to withstand a fire

for at least three hours,
which is more than 50% longer

than previous comparable tests.

The facilities and expertise
needed to conduct them

were to be found courtesy
of the US Forest Service

at the world-renowned
Forest Products Laboratory

in Madison, Wisconsin.

[energetic music]

We've installed the glulam
column with thermocouples

that allow us to monitor the temperature

throughout the glulam
as it's exposed to the fire.

And it's well understood that char of wood

forms around 300 degree Celsius.

So we can monitor that


through the depth of the column.

And then by doing that,

it enables us to calculate char rates.

Within 25 minutes, the
temperature in the furnace

will reach 1100 degrees Celsius.

It's this surface charring that is key

to timber's ability to withstand fire.

It forms what is sometimes referred to

as a sacrificial layer,

which acts as a barrier
to further combustion.

Once we obtain char rates
from the glulam column,

then structural designers
can use those char rates

to appropriately design the size

of their glulam beams and
columns within a building.

It's incredibly exciting
to be on the forefront

of all of this and to
watch these structures

going up very close by to us.

It's a really exciting time to be a part

of this type of research.

In contrast, steel behaves
in a very different way

when heated to similar temperatures,

which is of particular
concern in an emergency.

In the case of a steel building

when that fireproofing falls off,

the beam is gonna be heated.

We all know what happens
in metal when it heats up,

it expands, and a 100-foot column,

or steel I-beam will elongate

approximately nine inches
at 1100 degrees Fahrenheit.

Now that might not seem like a lot,

but imagine that nine inches

pushing out against the walls, right?

So that's nine or 18 inches on both sides

and that's gonna cause significant stress

in a lot of the catastrophic collapses

like we've seen on
these types of buildings.

What has reassured firefighters

is that laminated timber
behaves in a very similar way

to those solid timber
frames of centuries past,

and although badly
charred, it still retains

its structural integrity.

It's worth remembering
that in modern buildings,

sprinkler systems would
do their job long before

the need to depend on sacrificial charring.

The 21st century construction codes

are all about engineering
for the worst case scenarios.

We are looking at the
structure in these fires,

assuming that the
sprinklers haven't worked,

and these have reliabilities of,

you know, 95, 96, 97%.

So they're incredibly
reliable fire safety measures,

but we also start to look at, you know,

what if the fire department is delayed,

they can't get to the building?

And so we kind of rule them out as well.

So we're looking at, you know,

very, very sort of low likelihood fires

and looking at the worst
case situation for those.

And then we have to work out,

so what other mechanisms
and levels of safety

do we have to put in place?

In addition to sprinkler systems,

we have automatic fire detection systems,

which sound alarms and which allow floors

where the fire is closest
to be evacuated first.

We have certain systems
which protect stairs

with pressurized air and
they keep the smoke out.

And often they're within corridors as well

so that people can leave their units

and within a smoke-free environment.

And then also, we have lobbies for people

who can't walk downstairs,
and we have protected spaces,

which allow people with
disability to be able to wait safely

for the fire department to
come and take them away.

And often, people have no idea

that those systems are actually there.

They hear fire alarms and
they maybe have an idea

that there's a sprinkler in their building,

but often there can be a multitude

of other firefighting
systems, of water supplies,

and tanks and pumps and
all sorts of other systems,

which are in place, and
backup power supplies

to make those systems incredibly reliable.

So when they are needed, that they do work

and that's the most
important thing and, you know,

modern high-rise buildings
have those fire safety measures.

[mellow music]

Look at the brown of the wood.

It just it feels good to see that, right?

This is a future of construction.

This is Brian Brashaw and Steve Kuennen

who work for the Forest Service.

Their role is not only to
look after the nation's forests,

but to also promote the
sustainable use of timber.

Forests make everybody's lives better.



comes from forested land.

So, clean water, clean
air, wildlife habitat,

they support rural economics.

They support jobs.

They absorb carbon dioxide,

and they convert that into carbon.

For every one ton of its dry weight,

a tree will have absorbed
two tons of carbon dioxide.

Our mission is to maintain a healthy

and resilient ecosystem.

A healthy, resilient forest

are critical to our way of life.

Around the world, it's estimated

that 1.6 billion people heavily rely

on forest resources for their livelihood.

All of the trees that we're
looking at are storing carbon,

but we also have the ability
when a tree is harvested

and used for a value added product,

like Cross Laminated Timber,

or mass plywood products,
structural composite lumber,

those kinds of things, we
have the ability to store that

for another 100 years or
the life of that building itself.

So that's a long-term storage.

At a time when many forests

are under threat from climate change,

non-native invasive species,
and catastrophic wildfires,

if demand for timber
dramatically increases,

will that mean we'll deplete
this vital natural resource?

The good news is that Brian,
Steve, and their colleagues

from the US Forest Service believe,

as counterintuitive as it may seem,

that the opposite will happen.

Their research suggests that
increased demand for timber

will incentivize good forest management

and provide the funds with which to do so.

When we manage forest,

part of management revolves around harvest,

as we remove some of those trees

to create healthy conditions,

to be a healthier forest,
to be more fire-resilient.

And those opportunities to store carbon

in harvested wood products or in the forest

are certainly better than
seeing the carbon go up

in catastrophic wildfires
that we face nationally.

We have incredible opportunities

to naturally regenerate, to plant.

The United States has a wide diversity

of forest types and species.

And we have more forest than we've had

at any time in the last 70 years.

So biodiversity matters.

Why does it matter?

Because if we have all of the same thing,

if something goes wrong,

then all of the same thing gets wiped out.

It's important for us to
have different species,

different age classes,
old trees, young trees,

and actually areas where there's few trees,

but there's more grasses and other things

that grow symbiotically with trees.

To help create what they believe

will be a win-win scenario for forests

and a sustainable construction industry,

the US Forest Service has been proactive

in the promotion of
responsibly sourced timber.

The Forest Service has invested
in mass timber since 2014.

Part of that is education.

We need to make sure
that engineers and architects

and construction firms
understand this material,

how they can design with
it and how they can build.

And then market development.

We have a wood innovations
program that I manage

that supports early stage investments.

And those investments can
support engineering and design.

We're trying to diversify.

We need to have as
many markets as possible.

The more markets we have,

the more management
we can do on our landscape.

What it does is it expands our ability

to manage our landscapes.

In the case of Ascent, a proposal came in

to evaluate and provide
early stage engineering

and technical assistance advice

as they were planning this project.

And I think, even today,
I just get really excited

as I saw this building going up,

the ability to walk through it, you know,

the ability to put out and touch, right?

I mean, typically you don't think about

touching a concrete column,
or hugging a concrete column,

and certainly a place
I'd love to live someday.

You wanna hug it?

I know you do.

All right, good.

[mellow music]

Anything that can be made from wood,

we can figure out how to do it here.

We know how to use 100% of that tree.

We don't have to waste anything.

We have the technology
to do it, right now today.

And that's really important
for people to understand.

We can utilize the materials
that come from the forest

and regenerate more forest behind that.

So as you take a tree, you grow a tree,

or two or three.

One area of research

that the laboratory has been conducting,

which could have huge benefits
for the construction industry

is in the field of
nanocellulose technology.

Well, cellulose is a
major component of wood.

And so we're taking this component

down to its smallest scale.

An added smallest scale.

It has remarkable properties.

It's lightweight, stiffer than Kevlar,

and has a tensile strength
eight times that of steel.

And when it's used in concrete,

the crystals enable the
cement to bind differently,

making it much stronger.

The amazing thing about this material is

you can reduce the amount of cement needed

to have structural
performance by about 20%.

And so we're testing that now

out on a bridge, out in California.

It also has the potential

to form a basis of a much lighter

and stronger alternative to glass,

which is not only 2/3 more
thermally efficient than glass,

but also has structural properties.

We're still working out
some of the features of this

to get it to be completely
transparent, but we're 90% there.

And because nanocellulose

has the ability to conduct electricity,

if a combination of chemically treated

and untreated fibers are
incorporated into flooring,

when they come into
contact through compression,

they produce electricity, which means

that floors in places like busy hallways

could produce significant
amounts of energy.

So we can build a building,

the structural components from wood,

we can put flooring down
that's wood, even ceilings,

and now the windows, and have that produced

from a wood product.

And what if we could then take

another byproduct from a wood process,

such as in Pupa paper-making, the lignin,

and we can produce an insulating foam.

Now we've increased the carbon storage

in that building considerably,

a plant-based organic
building whose component parts

can biodegrade easily
and go back into the soil

to benefit the soil as organic material,

or it can be dissolved
in sunlight and seawater.

Then we would have a
purely sustainable system.

[mellow music]

As timber construction enjoys

a growing renaissance,

just what heights could
a timber building reach?

So, if we're making a
building entirely out of wood,

then the optimum
height is about 10 stories.

If we get above that sort of height,

we're going to struggle to make it

strong enough to resist wind loading.

The walls and columns
supporting that building

are really going to start to get quite big.

So it's above about 10
stories that it makes sense

to start to combine
wood with other materials.

Which is why Ascent, with its 25 stories,

has adopted this hybrid approach.

You're going to see hybrid systems

with steel as well as concrete,

that really allow you
to get the full aesthetic

and almost biophilia of
the space of exposed wood,

yet use steel where it makes sense.

Whilst it's unlikely that we will ever see

a timber building as tall
as one of John Peronto's

other projects under construction,

the one kilometer high Jeddah Tower,

it is at lower heights

where the true potential of timber

can be fully realized.

We talk about the glamorous tall buildings,

but the majority of what
we build across the world

is smaller buildings.

Just imagine if the majority of those

could be built out of wood,

imagine how much carbon dioxide

could be locked away
inside those buildings.

The best thing we can do,

whatever we build our building out of,

the best thing we can do

is make them last as long as possible.

From a sustainability point of view,

there is nothing worse
than demolishing a building.

All that effort and energy

that's gone into building
the building is thrown away.

Now conventionally, we talk
about 50-year design lives.

I want to change that.

I want us to talk about


even 200-year design lives,

but obviously, there will come a point

where that building has
reached the end of its life.

The next step is, can
we reuse the components

from that building in a new building?

And the beauty

of a prefabricated mass timber building

is that it is far easier to
dismantle and do just this.

[mellow music]

But possibly the most extraordinary vision

for a sustainable building

is a recent award-winning proposal

from Guess Line Architects in Ukraine.

Their idea is to create
a living skyscraper,

which integrates genetically modified trees

as part of the structure.

[mellow music]

As it grows, they envisage
their living skyscraper

could connect with nearby buildings,

forming a green network
over an entire block.

[mellow music]

[upbeat music]

Back in Milwaukee,

the full 25-story height of Ascent

has just been reached.

It's known in the industry as topping out

and as is tradition, it's
something to be celebrated.

Just six months after the
first timber was installed,

and having shaved 1/3
of the construction time

for a traditional build,

the final CLT slab is being signed

by those involved in Ascent's construction.

Everything went great.

That's about it.

You guys have a good day.

Still feels a little bit surreal

to be standing here and looking at that.

This is proof that tall
timber works, unequivocally,

and that is going to truly contribute

to changing the way that
buildings are designed and built.

There are people not
just in the United States,

but throughout the world, on social media,

sending their congratulations

for discovering Ascent for the first time,

because so many people are
sharing images of us topping out.

The phone is ringing.

People want to know how it got done.

Can they do it?

And so we're looking at timber projects

in three or four other states right now.

Our hope is to be doing these

basically all over the country.

So when people look at
Ascent, I hope they're inspired.

I hope they can see
that there's a way to build

a more beautiful product
in a more sustainable way.

Would you do it again?

In a heartbeat, we're
doing it again right now.

We're gonna do it again,

and hopefully, we're
gonna do it multiple times.

On paper, at least in
the city of Milwaukee,

we could build a timber
building up to 420 feet tall.

Project like this out of mass timber

will definitely help the
industry move forward.

And just because it
hasn't been done before,

it doesn't mean we can't.

It feels like we're on top of the world.

It really does.

It's great to see timber
reach these heights.

[bright strings music]

[mellow techno music]