- Hurricane Grace is back.

- So that's a multi-hazard storm.

So what can we do before the event?

- [Dr. Anne] Your structure is now more like a balloon.

- [Delphine] This is a really hard experiment to do.

- Water is thousand times heavier than air.

They are reproducing large scale phenomena of the ocean, but there is some limits.

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(gentle music) - We know wind and water can knock a home over, but for those that still stand, what physics, chemistry and microbiology might be at work?

- If this was just a typical home show, you know, we would just mop up the mess and replace the windows and the drywall and do a thrilling reveal of the rehab.

- Hmm, let's be more interesting.

The science of homes goes deep on this one and we'll hear about the latest research on hurricanes, tornadoes, tsunamis, and floods.

- And even the latest building codes might fall short of preventing our disasters.

(dramatic music) - It's the shields we build and the risks we take.

It's the disasters that will test us and what will grow from them.

It's real life and the physics, chemistry and microbiology of the science of homes.

- When you get a huge amount of water into a home or you have a really humid environment inside a house, then what happens?

There's a whole world of microbiology that people think about, but there is also the potential for a huge amount of chemistry to occur.

So when you add really high humidity, you're gonna make water films.

And you've seen this when you have a really humid day and you get water condensation on your, perhaps on the glass or inside your home.

So this is the experiment that we've done at Casa.

So we have pumped up the humidity of the house to 75% for several days in a row and watched the chemistry.

You can visibly see the water films forming inside the house.

It looks like the house is sweating.

We suddenly see not just the chemistry on the organic surfaces of the homes and on the paints, but we're suddenly creating this film of chemistry that can act just like a glass of water but with a huge surface area.

So we have this massive water film inside the house, gases that are soluble, so things that can move into that water film will all tend to move out of the gas phase and onto that water surface.

So we can watch them move by measuring the chemistry in the air.

And then you get reactions inside that water film and then we can see that pump out new and different chemicals.

This is a really hard experiment to do, but I think it's really relevant because with flooding events and with hurricanes, and these events are only going to increase with climate change, they already are, we're seeing more and more water in homes that is changing the composition of the air that we are breathing just by adding water.

- So hurricanes, we have wind, we have rain, we have wind-driven rain, we have storm surge, and we have flooding.

So that's a multi-hazard storm.

The thing with hurricanes and tornadoes, 'cause tornadoes are often also in the middle of severe storms where there's rain involved, is both of these types of wind events do create enough uplift that you see damage on the roof.

And that's a lot, again, because we're not designing to prevent that uplift.

And so when you have that uplift on the roof, you see the roof shingles start to come off, you might see roof panels start to come off.

You might see windows get broken by windborne debris.

So that's another important part of the hazard combination of these types of storms too, is the windborne debris that's creating missiles on our homes.

So now when you have damage to your windows, damage to your roof, and then it rains and that water gets inside, now it's gone from being a structural problem on the roof that maybe could have been fixed, once you've got all that water damage, everything's completely lost.

Inland flooding is becoming a really big problem in the United States, and I do think it's taken a lot of researchers, a lot of policy makers off guard because when we think about flooding, we think about coastal flooding.

So back in 2016, Hurricane Matthew hit the east coast of the United States and devastated parts of North Carolina in particular.

When that happened, we were able to mobilize and start a field study in Lumberton, North Carolina.

We've gone back to Lumberton six times now and we're planning one more field trip before the end of this project.

So that's really special.

Longitudinal studies that last for more than one time point is special, more than two time points is extremely rare, and to the best of my team's knowledge, which there's about a hundred of us, there's no one else who has data like this.

We survey the same 567 households every time, and then there's 350 businesses.

Many of the houses are still vacant.

They've been abandoned.

We recorded somewhere close to 20% of our sample is abandoned housing.

The public housing, as of the last time we did our study, had not been rebuilt.

Actually, what's really special about that community too, unfortunately, special about them, that was 2016 with Hurricane Matthew, in 2018, they were catastrophically flooded again by Hurricane Florence.

And then we all know what happened in 2020 with the COVID-19 pandemic.

So this community represents what's likely to be a new norm of being hit by repeated disaster before you're able to recover from the previous disaster.

(fans whirring) - We're standing in front of the wall of wind, AKA WOW.

- We can create up to a category five hurricane wind speeds, over 157 miles per hour.

Our goal is to certainly focus the wind towards the turntable where the structure is.

But a hurricane wind is not nice and straight and laminar and smooth.

It's actually very turbulent.

We have engineered into the system a turbulent flow that mimics a hurricane flow.

So over the ocean there's not as much friction, right?

So the wind speeds are pretty high over the water.

As that hurricane circulation moves on shore and then starts moving inland, it can drop tremendous amounts of rain at that point, but the strongest and highest wind speeds are typically right along the coast.

- We take information both from the laboratory and from field to put into our computational models because a lot of design now is done on the computer simulating a structure.

It is fraught with possible problems.

You put the wrong data into a computational model and you are gonna get the wrong answer.

Calibrating models from reconnaissance and what we see in the laboratory from experiments is essential before we can use those computational models to actually design buildings.

- Guys, I'm at the Institute for Business and Home Safety.

(machines whirring) Aaaahhhh!

(door creaks) - Whoa.

- It's quite the big space - Now inside this house, which they built by the way outside of this facility and then rolled it in, you can see the fans out this window here, it looks like a regular house except that we've got sensors and sensors in here with miles of cable connecting all this stuff.

- We can get over 400 sensors on a typical home, and we need the level of granularity to have the good science.

So it takes us a while to instrument these things.

And then we put 'em to the test for a number of weeks.

So we design our homes, our building codes and standards re designed as if the home remains intact and enclosed.

So if you introduce an opening, let's say a broken window or a large broken garage door, your structure is now more like a balloon than it is like an enclosed building.

And so, you know, all of that wind is gonna come into that garage space.

It's going to expand and push.

So the inside is now trying to pop out just as much as the wind is pulling on the outside.

It really dramatically increases the wind loads on the structure and leads to a lot of damage.

The flexibility and movement of the building products is critical to find out.

Sure, there's some things that we can't fail in this facility and we might need a facility that can do some stronger winds in the future, but I tell you what, I've got a lot of things to do first before we start thinking about that.

- So people who are looking for a new home beware because this is basically cardboard approved by code because they staple it in this very specific way, but it's only approved for the strength that it has when it's dry.

So as soon as it gets wet, we have a major problem because cardboard wet is not gonna hold up your house.

- [Grace] So aside from wind, which clearly we have, what else are you spraying around in here?

- We can do plenty of stuff in here.

One thing that comes together with the wind are raindrops.

So with the sprinkler system that we have here, right here in front of the fans, we can deliver eight inches per hour of, you know, tropical-style rain to measure.

How does that interact and where does it go?

Big raindrops and small raindrops, the distribution that you would actually see in a tropical storm because people have gone out and measured it and we are replicating it.

They are the correct raindrop sizes.

- Wow.

- It was a T word.

My wife doesn't like to use the T word, but yes, we had a extreme wind event according to what insurance companies like to call it.

There's not such thing as a tornado with the insurance.

It's an extreme wind event.

It was our trees.

We had six-foot diameter trees in our front yard, about 60 feet tall, 'cause it's one of the reasons why I bought this house.

It just shredded them to pieces.

Yes, we had rain immediately after, but in about two or three hours after that tornado we had another band of rain come through and so we got water in certain sections of the house.

I did best as I could.

I actually used towels and so forth where I knew water was gonna come in and so it didn't get into the living space too badly.

- So tornadoes up to this point, they're not in our building codes.

This is kind of bizarre to me because I grew up in Alabama, which is kind of the new tornado alley.

We get more than 1200 tornado touchdowns every year in the United States.

So they're the most frequent natural hazard that we have on record.

But they're very localized, and I think that's why you don't see them in building codes is they touchdown and their swath is relatively small compared to say a hurricane which may cross state lines.

Tornadoes are special though.

They have a really different kind of extreme loading pattern.

So if your building's standing up, you get this lateral movement.

You also get a twisting, and then you get a really strong uplift.

And that twisting and that uplift is what is so different about tornadoes than a lot of the other types of natural hazards that we study.

I know this show's about housing, but it was a really special thing we saw after the 2011 EF5 tornado that went through Joplin, Missouri.

There was a hospital that was completely destroyed.

And when I say completely destroyed, I don't mean structurally.

I mean non-structurally because the windows were blown out and the water came in and then everything was contaminated and they had to completely scrap the hospital.

So that was a really big light bulb moment for why we need to be designing for tornadoes.

Tornadoes aren't in our building codes yet but there were federally-funded investigations on some of that damage, and I was working on the committee that now has written tornado load provisions that has been adopted into the next version of the "International Building Code," which should be published in 2026.

So in 2026 we will have tornado loads, but even then those aren't for residential buildings.

So there's still a lot of work to be done there.

- The effect of the wind on structures is relevant and is very destructive.

We should not underestimate that.

Well, the difference between the water hazards and the air hazards is how heavy it is.

Water is thousand times heavier than air.

So you need thousand times less volume of water to produce the same force.

Wind needs to be significantly stronger.

Not a thousand times.

It actually goes to the square of that.

So 1 million times faster to produce the same effect of the waves.

The waves are not running that fast, but they are thousand times heavier and stronger.

From that perspective, once the water reaches the house, it's not only flooding that is the only problem that you have, is that the waves are able to go to reach your doorstep, and that is the major destructive process that you have a wave that is moving and is hitting your structure because you have the storm surge.

So that combination is then whatever happens with the wind is not relevant because waves dominate.

When we talk about storm surge or when we talk about tsunamis, the easy to understand dimension is how big are things.

So how high is gonna be the storm surge or the tsunami.

There was a warning of between one and three-feet tsunami.

To the surfers that are surfing waves that are eight feet or more, sounds like, well, this is not relevant.

The relevant thing of a tsunami is that not only is three-feet high, that it's super long.

It's 20 minutes long and that creates a change in water level of one foot that is moving inland during 20 minutes in one direction, and that creates significant flooding and forces that knock off people on the beach.

So when we hear about tsunamis in Banda Aceh that reaches as high as 40 meters, it's not because the tsunami is 40 meters high.

The tsunami was only 10 meters high, but it has the power to go uphill up to 40 meters high.

The movies are creating a problem in the understanding in the general public.

At Oregon State, we do have two very big facilities and they are reproducing large scale, sometimes even full-scale phenomena of the ocean.

But there is some limits.

We cannot make tsunamis that are 10 meters high or we cannot go as deep as the ocean.

So we have to reduce the scale.

Reduction of the scale allows you to do the testing in a reasonable cost of what you are trying to investigate and also allows you to go into the extreme conditions so you can control having something that may not happen in the next thousand years.

- The common perception around the turn of the century was that tsunamis wipe out everything.

So the only solution is to evacuate, to get everybody up to high ground.

Once it's safe to go back, you try to recover.

But Waikiki, for example, is impossible to evacuate.

There are 150 to 200,000 people in Waikiki at any point in time.

You cannot move that many people in the two to three-hour warning time that we have.

But what we saw in the 2008 Indian Ocean tsunami, even in the horrific Tohoku tsunami, there were people who survived by going up in taller buildings.

Multi-story condominiums, office buildings, that building designed for earthquakes, which is common in Japan and on the west coast of the US has enough toughness to resist the tsunami flow, even if that flow comes up two or three floors in the building.

Alaska, Washington, Oregon, California, and Hawaii are now required to design for tsunamis all critical and essential facilities that are within the tsunami zone.

- There is particular situations when the tides approach to the coast and are affected by rivers or the shape of the coastline.

The tide becomes significantly bigger and also becomes asymmetric.

And that is called tidal bore.

So tidal bore happens all the time in the Amazon River.

Is called pororoca, and is a natural hazard, but it is not causing disaster because it happens on a regular basis in a place that is relatively unpopulated.

The largest tidal bore in the world is in an estuary in China that is nine meters high.

So it goes from zero to nine in a matter of seconds in some locations.

So it was a natural place that it was not producing disasters because it was part of nature that people start populating, and actually it's a touristic attraction.

But when they were not controlling it, the tidal bore was producing disasters because of the population that was living here.. - When we first moved into this floating home, we were just on cloud nine.

And about the fourth night, I woke up in the middle of the night and I sat up in bed and I thought, oh my god, I don't know a thing about a floating home.

But neighbors are very helpful.

You can ask.

They'll be glad to come over and look at it and help get you through whatever needs to be done.

It was a one-story house that they built in the '70s.

They built a second floor in the '90s.

Early on there were no building codes and in that way it was the wild, wild west.

People were able to do whatever they wanted.

We've fallen in twice.

And you find that tools don't float.

- There are people that come and will dive down and get your stuff for a price.

I think there's a romance to living on a floating home, and the community that, you know, works to get together.

We have parties and it's a very congenial kind of atmosphere.

Helping each other, obviously, 'cause they saved our house when it was about to float away.

Or at least bang into something else.

It's interesting when you have parties because you have to tell people not to all congregate on one side or the other.

- The houses that are floating, normally you would see them in a body of water that are not moving or moving very slowly.

But if you have waves, the house will start moving significantly and then people inside, as a minimum, will get very sick.

But it could be even exceeding the design forces of the house and start twisting or maybe breaking or even over topping and capsizing and destroying the house.

So those houses or any structure that is not intended to respond to waves needs to be protected with other structures or other ways to affect the response of the house.

- When we looked at this home, they had very heavy furniture, so we knew that it would probably be okay to bring the grand piano and the waterbed.

We sort of knew that ahead of time, But when you take the waterbed out, which we did, then you have to figure out whether you need some more support underneath it.

- We really were conscious of it.

Grand piano, waterbed, LPs, living room, and they are great big giant logs.

And if they're underwater, then they don't decay.

And just like in the forest, you can see weeds growing on the logs.

You don't want that to happen here.

And so you get your bathing suit on, and when the water's warm enough, you go in there and scrape those off.

- It is counterintuitive, but if we want to protect the house is that the houses are on stilts.

So what people have done is removing that element that is in the way of the water.

So when you have storm surge, when you have waves, as long as the waves are not reaching my house, the house is gonna be okay.

So what we are researching is how to design that those shapes on those stilts, for example, on houses to minimize or control the amount of forces that are felt by the structures.

- One of the best things that you can do to mitigate wind damage, water damage to your home is just being educated on, yeah, what those tools are out there.

I think insurance is really important if you can afford insurance, but that's a bandaid for fixing it after the problems happened, right?

So what can we do before the event?

There's this really cool standard that was developed out of the IBHS actually, and it's called the fortified Standard.

- So this first one here on the left, we have your typical 15-pound underlayment.

It's just stapled on.

Now let's say we've lost some asphalt shingles and now this underlayment is sitting there exposed to the wind, and you're gonna show exactly how easy it is to pull that right off.

- Oh, that's really easy.

- That is really easy, and that is a very thin piece of material.

- This is not very different from the construction paper that my kids play with.

- Exactly.

That's what you might've used to cover your school books, right?

So the shingles come off.

That underlayment's easy to pull off.

And now we've got that gap between the two pieces of plywood that is just ready for the rain to come in.

So over here we have a 30-pound felt, so it's a little bit thicker, and we're giving it a better fighting chance because we've fastened it with more fasteners and using that button cap to try to keep it on.

- Okay.

- Yep, that one's gonna- - Did pop.

- Yes.

And this is why we got the safety glasses on this one.

Yeah, it's a little hard.

There you go.

- All right.

It'll rip.

- It will rip.

I'm gonna give you a help on this one because it is harder, right?

Oh, we're moving it all around.

- Okay, got it.

This is a workout.

- It is.

And so this particular roof is gonna have a lot more wind resistance.

This is a bitumen tape, and there are many that qualify, and it simply provides the bridge between the two pieces of wood so that the water can run right off and down into the gutter.

- Right.

And there would be little holes and penetrations from nails from the shingles, but you're not nearly as concerned as this gap.

So now Hurricane Grace is back.

- Now some of it you see goes over, but some of it is gonna go right in through this crack and down into the attic.

- Right.

- It does.

- [Grace] Look at how much water's going down there.

- Yep.

It is a lot.

So on a typical home, it might cost an extra $500 to do the tape.

- It's tape!

Right.

Tape is not an expensive building material.

- Tape is not that expensive.

But people have to get comfortable with it and learn that it's not crazy, Your plywood's still gonna get wet.

You might get one or two drips through those nail holes, but most of it is gonna make it to the gutter and it's not coming down through your insulation onto your couch.

- Wow.

Yeah.

- Sadly, my very own parents experienced what it means to have an unsealed roof deck, and I was literally standing in their kitchen with a broom handle, knocking holes in the ceiling to allow the water to come out without dropping the ceiling on my head.

- Oh no!

- Right.

So the amount of water that comes in and then just exacerbates the damage is terribly impressive.

- If you're building a home, that's the best time to incorporate this because we're talking about the structural system.

This is behind your drywall or behind your shiplap.

You can't see it, so it's not easy to access.

But hurricane straps that are tying your roof to your studs, we want more than just nails, more than even just screws connecting that roof system to your wall system and that wall system to your foundation system.

There's still a lot that you can do from a non-structural standpoint too.

If you are in an area where inland flooding or coastal flooding is a problem, when you're building, making sure your outlets are high enough off the ground, making sure that you're elevating your HVAC system, and then paying attention when you get those weather alerts and taking your stuff and putting it on the countertop, taking it upstairs if you have a second level.

Keep as much of it away from that water as possible.

Depending on what you might have in your yard, think about that windborne debris.

What is now gonna become a missile when it is being blown a hundred miles per hour at your house?

And picking up that stuff and bringing it inside.

And that'll at least go so far until, you know, everything becomes outside, right.

If you already have a home and you're not planning to build a new one, like most of us, then it comes down to, does it make sense to retrofit?

And I think that's kind of depending on where you live and what your hazard risk really is.

People do retrofit their home and add those things, but it's a pretty big inconvenience on the household to be able to open up their house that way.

- Whether or not you're ready to start preparing your home now for the wind and water that's coming, it's always better to know, isn't it?

- This season on hazards isn't really about if, it's when.

And frankly, we all need to know a lot more still.

- But before we all rush out and start spending money on the latest and greatest miracle fix, join us in the next episode as we explore unexpected side effects of many products being marketed to you as we speak.

- Learn tons more about all of this science and how to use it on your own home at homediagnosis.tv.

And we'll see you next time.

(gentle music) (gentle music continues) (gentle music continues) (gentle music continues) - [Announcer] "Home Diagnosis" is made possible by support from Broan NuTone.

Better Air.

Better life.

By the got mold?

test kit.

Real science, real simple.

By AirCycler, Retrotec, Rockwool, and RenewAire.

By generous support from these underwriters and by viewers like you.