Build Science 101: #8 Airtightness

In this episode Matt & Steve discuss the importance of air tightness in construction, ranking it second in significance after water management. They introduce the Blower Door test as a game-changing metric to measure air tightness, now incorporated into building codes across many regions.
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[@davemason1745]

Great content......Not a big fan of the background music.

[@bignicnrg3856]

Seriously.....so annoying

[@donna30044]

@davemason1745 Why is there even any background music?! It is totally unnecessary and annoying.😒

[@WBraxx]

Gives the video elevator talk vibes. 40 minutes elevator ride 😂

[@Michael_McMillan]

Is this guy a doctor? I can't read his handwriting at all! :)

[@chris7361]

Yes thank you gang keepm coming

[@JoshuaSpitaleri]

My understanding is that the nordic countries open their windows even in winter an hour before they go to bed. This is for fresh air, something you all are advocating for, and something we can achieve without opening the windows so we can control environmental variables. Doesn't negate what you talk about here, just interesting to note how important fresh air is.

[@theamerican7080]

I'm all for efficiency and reduction of heat/cooling losses, but I don't want the indoors and the outdoors to be completely isolated from one another as far as air quality is concerned.

[@stevenbaczekarchitect9431]

Please read what you just wrote?? Of course you want them isolated where air quality is concerned

[@theamerican7080]

@@stevenbaczekarchitect9431 I should have added that I live in a rural area where outside air quality is better than inside probably 90-percent of the time so, I'm not all that concerned with breathing higher air quality indoors as I do outdoors. Unless of course I had a compromised respiratory system or pulmonary issues, or I was elderly, I'd rather be exposed to a natural air environment to keep my immune system busy building strength.

[@Micahj15405]

​@theamerican7080 You can bring outside air with controlled inlets if that is applicable for you. Ie, windows, doors, etc. Im sure there are whole home air filter systems that would give exactly what you want with exterior air.

[@johnwhitworth2381]

Matt, could you talk about ductless ERVs in some future video. We have no ductwork in our home and using mini-split heat pump for heating/cooling. After a remodel our home is now so airtight that home air pollution is now a real issue, which we’re regularly reminded of by our Airthings sensor. Without ductwork what options are there out there to solve this tight home issue

[@MrAntkoe]

You have no bathroom fan? Use that for your ventilation

[@connorgarrett7064]

Lunos is a much better solution than nothing. You'll need to run low voltage to each fan but that's it.

[@cartoon-network814]

best show yet - this esplains how we are just wasting energy by not making our homes not air tight

[@jesinbeverly]

50 pascals over the entire surface area of your volume turns in tons pretty quickly.

[@greg925911]

So my question is, on that 20 Million dollar home and those 4 foot over hangs, how would one stop that problem

[@levijones7453]

What app is Steve using to redline?

[@SandyFunnies]

I live in a house in Maryland built in 1997 and it leaks like a sieve. I believe it wouldn't be able to get a blower door test. I still see new construction with sloppy tyvec.

[@nicholasgiovingo7043]

if only the track home builders would take this seriously and get on board. the idea you can have all these properties at the cheapest possible cost is the biggest joke in the whole industry.

[@mjoelnir1899]

The artightness here in Iceland happens on the inside of the outer walls. The insulation of the outer walls is always vented to the outside. You have a venting space between the water or rain protection and the wall. We have of course a rather cold climate. The airtightness and the vapour protection is here the same layer. You never let the vapour from the inside go into the isolation of the outside wall. Electrical lines and water and the water and other pipes on the inside of the artightness barrier. Why in the USA is the artightness done on the outside of the wall?

[@StainGlassProduction]

It definitely depends on your location's climate. In a place like Texas, it's often very hot and humid outside. Therefore, you place the air-tightness on the outside to prevent moisture from penetrating inside. Whereas up north (say in Minnesota), it's standard to have your vapor barrier on the inside of the exterior walls (although most buildings do a crappy job at it). Since the US is so large, the answer is really: "It depends".

[@mjoelnir1899]

@@StainGlassProduction When you are venting the isolation to the inside, how do you get rid of the vapour?

[@StainGlassProduction]

In southern states, the vapor barrier is often on the outside and in northern states the vapor barrier is inside. The walls either dry to the inside in the south or dry to the outside in the north. That is traditional, however now some northern builds are adding air/vapor barriers on the outside and a "smart" vapor barrier on the inside that allows moisture to dry to the inside while preventing moisture from entering the walls/insulation

[@kennethharman2779]

We typically get around 1.2-.75, ach 50, our best was .26 ach50

[@stevenbaczekarchitect9431]

Great!!!

[@yodaiam1000]

So what do you do about an attached garage? Is it inside or outside? I am designing mine as if it is outside but I have a attic space above the garage where some mechanical might go. Can I make the garage outside and the attic above the garage inside? How does that complicate vapour and air barriers? I don't want to vapour barrier the ceiling of the garage and vapour barrier the floor of the attic since that will trap water in the ceiling. How do you detail this situation to let vapour out?

[@stevenbaczekarchitect9431]

Always outside, it can be conditioned, but always outside

[@kentoakley9409]

Good video. Question? Do you have a cost efficient way to cool the attic (unconditioned) to reduce the delta. I too live in very hot Texas. I have heard that putting solar roof top fans don't work. It isn't feasible to convert the attic to a conditioned space since the rest of the house isn't tight.

[@ericschmidt5996]

Question, I’m having my attached garage ceiling sprayed with 7” of open cell. The existing drywall was removed as well as the existing r30. I have a master bedroom above the garage. Will I need to install a vapor barrier? Located in zone 5, thanks for any help!

[@CharlesGrace-z8l]

I do not get putting the air barrier to cold climate location. I have a Gore Text jacket to it breathe our vapour. Otherwise, I have condensation mugginess to me and my clothes So in yhe UK we have an internal vapour barrier. Then breath the structure out. To roofs or timber frame we have a breatherble memrane to control air penertration. But all the vapour to get out of the structure. We normally have brick wall with air cavities. Which we have tendered to fill with insulation. Which removes are drainage / centilation cavity..

[@romerbarrett4179]

I'm a 1950 house in climate zone 4. My house does not have interior insulation. The basement has cement blocks and bricks, and the rest of the house is all bricks. I would like to know if I can put foam board insulation.

[@TheOnlyFredo]

One issue I can't figure out. I have a 2800SF ranch with a large attic I plan to finish. I am going to use closed cell foam at the roof rafters and possibly a combo of closed cell and batt at walls. Does it matter if my soffit is vented or not? Right now I have vented soffit in site ready to be installed.any suggestions?

[@machickman4041]

Great stuff. Love a conditioned attic and being able to use it for storage and hvac.

[@randallcotner2155]

The monolithic dome home I'm building in the near future will be very tight, even around windows and doors. It'll finally be great to really reduce dust, with the conditioning an filtration of the air being pulled in through the exchanger:)

[@jamescole1786]

11/16/23...👍 on yur informational video today. Glad to hear both you & Steve Identify Joe Stebrik (spelling not right) as PhD with many insightful science proven methods, products & measurement tools to build the best possible air/moisture & temperature resistant home available. A+today guys!😊

[@koenraadprincen7212]

It's Joe Lstiburek (Building Science Corporation) :-)

[@josephraccuia9870]

If you want to measure the air tightness of the envelope then measure the cfm per sf of envelope at 50! A 1,000sf house with four corners and 1.0 ach@50 is a lot leaker than a5,000sf custom home with 20 corners at 1.0ach@50!

[@Timeculture]

That is very interesting

[@Timeculture]

So I totally agree that if they’re going to standardize it in the building code, it should be a factor of the SF of the house in question. That makes sense

[@asabriggs6426]

Thanks guys, I'm enjoying the series and finding it really informative (as DIY-er across the pond). Can't wait for the 201 lectures to come out. Keep up the good work!

[@masoudnobar6314]

🙏

[@bradyusko6333]

Not true Steve, it's not always hotter at the ceiling than the floor. Just shot the temp of the floor at 72 and ceiling at 71 and wall temp at 5' 71.3. So a well build house has very little temp difference. Thermal mass makes a difference too.

[@CasyMint]

Joe Steber? Can't find any info

[@felixcosty]

Thanks for the video. When I was fixing my first home with my Dad who built home from the 60's to the 80's, and we took the gyproc from the outside wall around a window that was leaking, and the pink insulation was all black, he said this is not good this house has way to many leaks. This house was a 70's built house.

[@MoonMoon-gu2ge]

Sorry guys, love your content but couldn't make it past 2min with that music. My tinnitus is eeeeeeing

[@beachboardfan9544]

Canada has had these standards for the past 15+ years. They use closed cell spray foam and then theres a caulking that gets sprayed into every seam and joint on a wall.

[@braxtonmann9459]

Cool video

[@lrc87290]

At what point do you need HRV or ERV?

[@ytgord]

once your house is tighter than ach50 3.5

[@briannorwick]

Thanks for taking the time to create this series!

[@BrianBriCurInTheOC]

Idaho has 4 Counties which Have No Building Codes and several States are similar

[@lrc87290]

Just the wall cavity needs to breath.

[@jerrydowell7202]

So helpful! I had been trying off and on for weeks to figure out why I couldn’t get my trailblazers front brakes to bleed. After trying this tip, I was done and test driving it 15 minutes later. Much appreciated! Thank you!

[@dustinabc]

Good ideas don't require force. Strict building codes are an excellent idea. But mandating them is a very bad idea.

[@Micahj15405]

Some of these builders have no reason to change. Their labor is happy with how they do things now, and the builders don't want to change anything as what they have now is profitable. Only way they'll come into the modern era will be by force(code changes) and/or prices for these techniques somehow become cheaper while the end user demands the changes.

[@bignicnrg3856]

Love the content......but Matt is annoying and loves to hear his own voice 😂

[@cp37373]

Fact.

[@lancedoyle5026]

good simple explanations

[@wademartin8822]

Amazing episode!!!

[@randomrazr]

holy jeez 40mins

[@durgaprasadala]

Reiterating building science. 100 times.... 40 minutes can be filtered to 4 mins.

[@stuartrinker]

We live in north Idaho. Always have a window open. That fresh air is so refreshing especially in the winter.