Episode 206: Air Sealing and Insulation Layers

There’s a fear abundant in the general public that houses “need to breathe” and they shouldn’t be built too tight, but what does that mean? House wraps, all-in-one Weather Resistant Barrier (WRB) sheathing, tapes, foams all can help seal a house tight, but then it must be ventilated right. And insulation in the cavities of your walls is good, but how can you add a continuous jacket of exterior insulation to really up your family’s comfort and energy efficiency? Every home is a system, and the skin of a home is as critical as the skin of your body.

Featuring a consulting/testing visit to Anna’s new house, where she’s having some trouble with moisture condensation, high performance enclosure expert Johnny Rezvani of 475 Building Supply, Matt Risinger of the Build Show, and the cherry on top: a field test of wind driven rain, or ‘Hurricane Test’ by Landus Bennett, using a pressure washer and 5 blower door tests at the same time.

DIVE DEEPER WITH THESE RESOURCES:

TRANSCRIPT:

Coming up on Home Diagnosis...

We are literally turning our home into an airtight submarine- why?

Buildings have evolved quite a bit in the last two decades or so.

Yes, we're going to have eaves.

But why do we not have eaves right now?

The skin of the house is a huge deal.

Right now Landus is pressure washing my house and I'm really hoping that it is watertight.

"

Home Diagnosis is made possible by support from the Alfred P. Sloan Foundation,"

by Fantech, 'Breathe easy,'

by Broan-NuTone, 'Come home to fresh air,'

by Aprilaire, 'Everyone deserves healthy air,'

by AirCycler, Retrotec, and Santa Fe Dehumidifiers,

by generous support from these underwriters

and by viewers like you.

In the previous episode, we dug into the invisible impacts of windows and doors.

We went back in time, to when shelter meant just a tree in a field, added a nice cozy fire, put walls around it and cut windows and doors in those walls.

Well, we've only been putting glass into windows and homes for a few hundred years, and once we do that, we start to notice another phenomenon of home performance.

When you solve big problems, you are able to start noticing smaller problems.

So drafts probably started to bug people at home, and that's when we would have actively started air sealing our homes.

In case you didn't know, most homes also had no added insulation until the past 100 years or so.

And that really helps control comfort, but it also has some surprising side effects.

So now we'll look into the single most important system in any home: the enclosure. Let's do some science.

They say home is where the heart is.

And we certainly put our heart into building our first house.

So how hard could it be to build another one?

I'm Grace.

And I'm Corbett.

In our TinyLab, we helped homeowners gain control of their homes through scientific testing. Now, as we build our forever home, we're testing ourselves.

Even though we know a few things about the invisible dynamics of homes, we're teaming up with scientists and building experts to design and build a perfectly-tuned home for our family.

The physics, chemistry and microbiology of a home might seem mysterious, but it doesn't need to be.

While this is a personal story full of twists and turns...

It's also the story of the science of homes.

Join us to unlock the mysterious science of your home, too.

Just like the skin on your body is the biggest organ, the skin of the house is a huge deal and you want to start planning for this in the planning stage, which obviously we did.

And here it is installed.

There are a bunch of ways to control the indoor physics and chemistry of the house using the skin.

On the TinyLab, we used a clothlike membrane.

And here we're using an all-in-one sheathing that has the weather resistant barrier on it, so it makes the job a little bit faster.

In either case, we're going to be using tape to make sure to seal the seams.

No matter what kind of project you're doing to an old or a new. Home. The skin should be of central. Importance, and. You should definitely be planning for that.

On Home Diagnosis, we break down the invisible physics and chemistry dynamics behind how every home works using the 4-3-2-1 approach.

Our one goal is to control the two systems, and the most important of these two is the enclosure.

Your home's enclosure is made of the air seal and insulation layers.

And better air sealing is the first of three recommendations we'll usually make.

It's the first recommendation not only because it's inexpensive, needs no maintenance and uses no energy, but also because it has a super power.

It controls all four of the elements of home performance.

Heat bleed: air sealing can cut down on a lot of the heat bleed you might think is due to A/C or insulation problems.

Airflow and pressure: air sealing and fans are the only significant ways to change this.

Moisture: most wetness in homes is in the air, so if you seal for air, you're also sealing for moisture.

And air quality: if you don't control where the air your family breeze is coming from, then you can't know if it'll keep them healthy.

But if you look in the phone book.

Do people still do that?

You won't even find a category called 'air sealing.' And that kind of thing is why we make Home Diagnosis- to show you what you haven't been told about why your home gets out of tune, and how to make it all better.

Buildings have evolved quite a bit in the last decade, last two decades or so.

We are still using a lot of the components that you would use, let's say, 50 years ago. It is still stick built and still wood-based.

You're still using screws and nails to put things together.

But the layer beyond that is changing fundamentally the way that we build to address the 21st century challenges that we have.

And those things include greater amount of comfort, greater amount of control over your environment, greater amount of air filtration and indoor air quality.

All of these things can be addressed by the way that you choose your materials the way that you put them together, and the way that you test and ensure the performance of a building.

Many homes built today don't have their performance ensured or tested. But it's never too late.

When you guys did your gut renovation on this home, did you already have performance in mind or was that something that was brought to you as a concept?

We didn't really talk about it. We were using a very good builder, and we just kind of trusted the subcontractors to do what they needed to do to make the house work.

So how has the performance of this home been?

Then we started having issues, major issues a couple of years after it was finished.

They did spray foam insulation, and we saw that we were getting a lot of condensation on the windows and couldn't really explain why that was happening.

Thought it was a window problem. So we ended up calling an HVAC company to come out and figure out what was happening, and they tested the house and the house couldn't breathe.

And so we were having condensation issues. They brought in outside air and encapsulated our crawl space.

We stopped seeing condensation in the main living space, but we still had issues in an attic space, sweating on the door from the attic into the house, and that room was just really very humid and hot, so it half-fixed the issues.

Alright Corbett. You ready?

Ready.

All right. We're going to run some tests and figure out what's happening.

Awesome.

So, the crawl space. Now, looking around here, having heard that it's been encapsulated, the story is a little bit more complicated than a typical encapsulation would be.

And part of it has to do with this insulation in the ceiling, which is spray foam.

So the first thing to do is to cover up the dirt floor in here with a thick plastic vapor barrier, basically, to stop the evaporation of the wet soil up into the house.

That's a good thing. But they used more spray foam to glue this plastic to the columns and to the walls and things like that.

It's not great at doing all things, and some of the marketing says it's a silver bullet that will solve all your problems, and that just can't be true.

There are no silver bullets in home performance.

Now all of this spray foam has flame retardants that come out of it.

All of this stuff is very useful for certain situations.

But it also is kind of a science experiment every single time you put it in.

So the installer of this is the most singularly important person in the entire chain.

Based on what I'm seeing here, this installer was in kind of a hurry.

Maybe not trained and maybe not paid as much as they should have been.

But the fact that this is insulated up here, and then also at the walls means that the crawl space is not part of the house.

And it's not part of outside. So what is it?

It's possible that it's like our studio space is going to be, and it's just its own separate little house.

In which case we don't know what is going to happen in here, temperature-wise and humidity-wise.

The company that did the encapsulation knew that, which is really good.

We have a monitor system and we also have a dehumidifier that you can see ducted right here into this space.

Let's go upstairs and take a look at that side attic and what's going on up there.

All right. So, good news is that the insulation does not appear to be very confused.

We have continuously insulated roof, not insulated at all on the floor, which is the right way to do it.

You want either-or. You don't want both, and you don't want neither.

There you can see the recessed can lighting behind me. That's good that it's exposed.

That's what it would look like in your attic if you had all the insulation out.

So you can see what a huge bunch of air leakage that could be.

Now, the solution for this water issue on the back of the drywall has been to put a dehumidifier in this side attic.

It seems like there is hot, moist air coming in here in the summertime and then meeting up with a called back of an air conditioned space, which is the living space right next to it.

So what we're going to do is, of course, run a blower door and we're going to run a zonal pressure test on this space, see if it's connected to outside.

Then we'll come in and we'll try and pinpoint exactly where this leak is so that we can solve it once and for all.

And this house is 4,300 square feet.

The rule of thumb, if there is such a thing for people who run blower door tests, is you expect about one CFM per square foot.

So, 4,300 square foot house- about 4,300 CFM. And look at that.

We're coming right in at about 4,300 CFM.

Which is a little concerning, because this house is supposedly completely spray foamed.

And this is not the performance that the spray foam companies are trying to sell.

And that's the thing is that if you're going to have your house spray foamed, and part of the reason that you're paying twice, three times, four times as much than for conventional insulation, is because it's supposed to air seal as well.

You always want to prove it.

Just because somebody says that it's going to do something, doesn't mean that that's the case.

Now this door has been opened while we do the tests because, of course, it's supposed to be part of the house.

But when we close it, you can see that number one, I can feel a huge breeze here, and we could pick that up with smoke.

And I can see that it's blasting right into the room.

The next big thing is a zonal pressure test.

Since this is an inside room, we want this top number to be zero.

It's not zero, it's nine.

Which means that there's an 18% connection to outside in that room.

Even though it's supposedly all air sealed, and it's inside the house.

That's a big number.

Now I have proven that there is air leakage inside that room.

All I have to do is go inside and find it with an infrared camera and with my smoke.

We can see that there's definitely 50 degree air coming in around this chimney.

I'm just going to check that with smoke.

And yes, you can see pretty clearly, I hope, that this is a huge leak.

I can feel it, you can see cobwebs shaking in the wind.

And that's another indicator- spiders always spin their webs in places where air is moving through.

And so if you see a cobweb, that generally is an indication that there is an air leak there.

So this is actually a very fixable problem. They've completely left this unsealed, but this is not a fireplace flue.

This is not a furnace flue.

This is the vent for the kitchen, so it's not going to be super hot.

In fact, by the time it gets up here, it's probably cooled down from whatever it was, even if they were firing all six burners down there.

So this could be easily sealed with, if you wanted to be really safe, a fire safe foam, if you wanted to match all the rest of the foam.

But this can be sealed with simple fire caulk, and it would take care of this problem.

This is definitely the most major leak that we found in this attic.

But of course, we would scan the whole thing just to find all of them, since we've got the blower door, since we've got this equipment.

We just go ahead and identify everything so that we can come back and fix it later on.

This fix is literally going to be half a day for one person.

There are a handful of rooms in a house that commonly proved to be very confused about whether they're indoor or outdoor spaces when we test them.

And we'll put attics and crawlspaces aside, and quickly touch on one that's often much more dangerous to your family's health: the garage.

Think about all the contaminants in a garage.

Gasoline canisters, paint cans, cleaners, solvents, and cars, which make carbon monoxide when they run.

We don't want any of that stuff under the sink. That's why we keep it out there.

But testing proves that many garages tucked against or under living space actually breathe right into the home.

And it's not the connecting door we're worried about.

It's actually the wall and ceiling cavities that often tunnel directly into the house.

Depending on how a home is constructed, it can be simple or more complicated to seal these leaks.

But remember, even if there are no exhaust fans creating suction, any time it's cold outside and warm inside your home is sucking in air from the bottom to replace what's pushed out of the top.

Garages are always on the ground level, and that's where the home breathes in all winter long.

So never run your car in the garage, whether the garage door is open or not.

You can find out how much your garage is breathing into your home by having a blower door and zonal pressure test performed by your builder or your home improvement contractor.

It takes literally half an hour of science to figure this out and set your mind at ease about the air your family is breathing.

This is our friend Landus Bennett.

He has been in the building industry since the seventies and is also a wood scientist, so we've brought him out to our build to kind of torture my house.

Exactly. So what we do in the lab is we do water penetration tests, especially around your tape on your sheathing, and the windows.

And we do that by spraying water on it and pulling a differential pressure.

So what we're going to do here is you're going to pull the blower door test.

You're going to pull a pressure on the inside, and we're going to spray the outside of the building.

Then we're going to look for leaks.

All of the sheathing, all of the wrap, the tapes...

The whole enclosure, yes- the tape, the seams, the windows, the doors, the whole enclosure.

If he can pull the blower door test pressure high enough to where we're simulating inclement weather, wind driven rain...

this is a test I think that builders should consider that they can do on site.

You don't have to go to a lab to do this.

I think that this is where the anxiety becomes reality that you can fix.

It might sound like a nightmare to some people to have your anxieties become reality, but it's nice to know where the problems actually are and where you just think the problems are.

We have the pressure washer running outside.

I'm going to run the blower door to a much higher pressure than normal- we just ran the test, which is only to 50 Pascals.

I'm going to run it up to more than double that to start this test. 125 Pascals.

I can actually feel that in my ears.

Now I've got my infrared camera, I'll be able to see the water as it's coming in when Landus about to blast this thing. Here we go.

Right now, Landus is pressure washing my house, and I'm really hoping that it is watertight.

Not seeing any obvious water coming in. And just to make sure that we're doing this right, I'm going to go ahead and take this up to one inch of water column, which is 250 Pascals.

OK, we're spraying pretty hard on the window, and what the blower door is able to do is pull the water in around all the things that might not agree with gravity.

So we're actually pulling the water up and into the window to see if any of it comes out here.

And the infrared can see things that our eyes can't see.

But even with it, I can't really see any water.

A little bit right here. Just to remind me.

We're also testing the roof here.

We have spots that you can see I marked out in orange paint already that were from when it rained, naturally, and we fixed them.

And of course, the whole thing about performance testing is, it's before and after.

So we tested it with rain. Then we fixed it. And now I want to see what I did actually worked.

People are often asking, 'Well, how much does this cost per square foot to build?'

The unsatisfying but correct answer is: how much for a bag of groceries?

You know, it depends on what you put in it.

The putting on the tape is not difficult.

It's when and how that you might be doing it.

If you're thinking about it in three dimensions, as you're building, you're going to have to put on first layer of structure, then the air barrier, then the second layer of structure.

And a lot of people will get that wrong the first time, and they're going to put their structure together and say, 'OK, the structure is done. Now let's think about the air barrier.' Well, you missed your chance to do it easily.

We often see people having real challenges the first time they're building differently.

The real challenge is integrating these different components and methods.

Once you overcome those challenges the first time, you probably know it the next time.

Our most common track for a lot of professionals is they do it on their own home, or like you guys do it with your own home.

You've done that trial and error. You figured it out.

You figure out your favorite way.

Now you can go and export it to the rest of the world.

There are tons of ideas out there for improving home performance, but not all of them are good ideas.

Some of them show a fundamental misunderstanding about the dynamics of physics and chemistry, which is what Home Diagnosis is trying to clear up.

So here are a few tips to avoid silly fixes that usually under-deliver on results, and cause more side effects than they're worth.

First, replacing windows in your home is rarely as helpful as you'd think.

Even if you double or triple the insulating value of a window, you're probably not going to reach the same heat resistance as an uninsulated wall.

Trying to insulate a home using windows is a drop in the bucket when you're looking at the home as a system.

Plus, we can stop wrapping water heaters in insulation.

They come with insulation built in nowadays, so if you want to insulate something, insulate your hot water pipes instead.

Next, heating strips or wires are advertised to stop pipes from freezing and ice dams from forming on roof eaves.

If you have either of these problems, they're likely caused by air leakage, which is why we make such a big deal about air sealing your home as a first step.

And if there's air leakage from your home into your attic space, don't let anyone install more attic ventilation, especially attic fans.

Whether they're solar powered or not, attic fans can depressurize your home's interior and cause air quality issues.

The idea that attic fans can lower the heat in your attic saving you cooling costs is silly if the attic floors are sealed and insulated properly.

Attic ventilation is primarily for controlling moisture anyway, not temperature.

We can all make smart decisions about our homes if we think of them as systems and test to prove what's causing problems and how to fix them.

We always want to kind of follow the four orders of importance on the house.

Yeah, really, the most important thing for a house is making sure our waterproofing is correct.

The next most important thing is making sure air tightness is correct.

The third thing is making sure a vapor barriers are in there in the correct spots and are done correctly.

And then lastly is insulation.

You know, we can have the most insulated house in the world, but if water leaks into that wall cavity, it's all for naught, you know, the house is going to fall apart.

The key to our enclosure, just like any good enclosure, is in layers. In redundancy.

You don't want redundancy that's like glasses and contacts at the same time, because that doesn't work.

But there's such a thing as belt and suspenders. You are absolutely sure your pants are going to stay up.

So here on the outside, we have our air tightness and water tightness layer in one.

It's called a WRB- weather resistant barrier.

It is taped at all the seams. It's also our sheathing, so it was one step to put up.

Followed by the exterior insulation. This is mineral wool- it's basically. Made of rocks. So it can be exposed to the weather.

This is two inches thick. Why not three inches? Why not just one inch?

Well, the energy model is the answer.

Now, this two inches is protected by our rain screen.

This is a 3/4 inch thick screen, basically, that's going to create this air gap between the siding that's going to go on outside of this and the surface, where rain, in case it gets behind our siding- which it probably won't- but just in case, it's able to get in here and either dribble down or get ventilated out and get evaporated.

This is something that's going to make my siding last years and. Years longer.

And I won't have to paint, or stain, or replace like other people do on a very regular basis.

So all of this breathing space, what Landus was talking about with 'drying potential' is really what all of this comes down to.

In addition to, of course, the control over the interior physics and chemistry.

The way that the foundation wall to above grade wall junction works here is also really cool.

We'll have the two inches of insulation, plus the rain screen, meeting up with our three inches of insulation.

As you can see, they pretty much line up here.

The cladding is going to go over here and we're going to have something that can resist being buried underneath the ground, and you'll see what that is when we get there.

But here we're going to have a bug screen, so that bugs can't get up inside of this nice warm cavity that I've made. We don't want that.

These outside layers of the enclosure are continued on the inside where we have cavity insulation.

If your house is insulated, it's probably insulated like this- with insulation stuffed between the studs.

That is not great by itself, but it is great when you've redundantly added the exterior, and we've got two layers of insulation working for us.

There should be no gaps anywhere- zero.

There should be no compression.

So if I put this insulation in here and I tuck it in like this, that hurts the insulation.

Because the main ingredient in insulation, you know this, is air bubbles.

This is a two by four wall.

We filled it completely full with the same exact mineral wool insulation, and we've added another air tightness layer.

This is going to give us that 100-year air tightness, because we have a redundant layer on the outside and on the inside.

Now, the fact that we filled this full of stuff that we care about on this show means probably it's not a good idea to put things like light switches, electrical outlets and plumbing in a wall like this.

But of course, we're going to need those things, so we are going to put them on interior walls.

Now, if you follow me into our really big room, you're going to see a different kind of construction.

Even though we're using the same insulation and we're using the same air tightness layer, we're using a different construction principle here, because the two by four is now a two by six, and we've created a two-inch pocket for us to put those services.

Now this is going to go all the way from the floor, where you can see it's sealed, up to the ceiling, where it continues uninterrupted.

The ceiling insulation is thicker than the wall insulation, and that's again because of the energy model.

We have also added the radiant barrier.

Now, radiant barrier doesn't work well in all climates, but here in Atlanta, Georgia, the radiant barrier is the perfect solution for us.

So even though our house is starting to look like a house, if you look at the edge, you might notice something is missing.

There's no eaves. Which is normally a bad thing for a house.

Eaves help get rain off of the house.

The TinyLab doesn't have eaves, but the TinyLab was built for the road.

So the answer is: yes, we're going to have eaves.

But why do we not have eaves right now?

Up on the roof, you can see it a little clearer.

We've got the roof underlayment coming along, being taped again to the wall, going down and being taped to another section of the roof.

Now here is where the eaves are going to come out, so we're going to attach what's called a 'ledger.'

After we've made sure that this shape itself is airtight and watertight, we'll put that on and hang these eaves from them.

So we'll have two feet of rain protection everywhere around the house, in addition to the extra overhangs at the front and the back.

Building to code. Home inspections.

If you're getting a passing grade, why bother doing more?

Life is expensive. Don't spend more than you need to, right?

Look, I like a good deal just as much as anyone.

And if something does the job well, I'm not going to pay more for brand or bragging rights.

But remember that where performance is concerned, 'code compliant' is the worst we're legally allowed to build to.

Maybe aim a little higher.

And here we are, normal people building our own home.

OK, it's not so normal, but we are literally turning our home into an airtight submarine.

Way beyond code, way beyond the point of energy savings, even.

Why? Because I'm OK with paying a little more and waiting a little longer to gain more control over my family's health.

I want to know exactly where the air my family breathes is coming from.

I want to make sure that any off-gassing, dust and pollen, or other contaminants are being exhausted or trapped in filters that I can monitor, and that my home's pressures are equalized.

Home performance is not a one-size-fits-all approach.

You can have as much control of your home's physics and chemistry as you want.

You're deciding for your family, whether you knew it before watching Home Diagnosis or not.

The jacket that keeps your home comfortable, or not, is a pretty simple thing.

But the details can get very confusing, which is why we try so hard to make this show clear and concise.

And there's so much more we can explore about the air sealing and insulation in homes, and their fascinating side effects.

One of these we'll dig into in the next episode is fire.

Once we've made our homes less vulnerable to air leakage and heat bleed, the fires happening around us at home start to have a more interesting impact on performance.

Tune in next time.

Home Diagnosis is made possible by support from the Alfred P. Sloan Foundation,

by Fantech, 'Breathe easy,'

by Broan-NuTone, 'Come home to fresh air,'

by Aprilaire, 'Everyone deserves healthy air,'

by AirCycler, Retrotec, and Santa Fe Dehumidifiers,

by generous support from these underwriters

and by viewers like you.