“Airtight' Buildings Debunked by HOMEChem

I've been telling people that the 475 High Performance Building Supply membranes I build with are airtight but vapor open for years. Turns out, sometimes I'm an idiot. Here's the real deal. Featuring Delphine Farmer and Marina Vance of the HOMEChem Experiment.

[lazywhale]

Yes, by all means, go with a high quality building envelope and keep an eye on the type of foams (and other plastic based materials) you incorporate in to your construction.... Then remember that that super luxury sofa with 4 inches of foam rubber comfort along with the vinyl covering and the 1000 lb of carpet you install will off gas far more than the building itself. The only solution is to ensure you have a recovery ventilation system to provide the building with enough fresh air while minimizing heat/cooling losses.

[HamidA-tovy]

I think it's a terminology problem. It might be better to call it a wind barrier rather than an air barrier. The old technique was to place tar papers on top of each other, sheding the water out yet allowing the water to escape at the same time. Until Tyvek came up with a membrane similar to what is used in rain jackets. I think Tyvek know a lot about chemistery. Speaking of vapor barrier, experiments has shown that vapour can travel through drywall. If it takes months for glass water to build up, it will still cause the same problem, and months is a very short time for a house

[Sub-Zero-Homes]

"Air tight but vapour open" A house brick can transfer water through it by capillary action but it would require high pressure to allow air through it.

Most of everything in the universe is empty space. A brick has more empty space than matter. Technically there is no difference between a gas, solid and liquid. But you can't compress a liquid but you can a solid so which really is solid. Liquids and gases act differently. The fact the individual molecules may be the same size isn't a deciding factor because it is how they are arranged in a group such as carbon. A diamond is carbon and so is graphene but they are very different as a fully formed structure. Air and heat are two different things too.

[EdBartley]

Yes, everything has a leak rate. And no, you're not an idiot; the fact you made this connection is proof. We could build walls out of 10m thick lead and still have a leak rate. It's a question of magnitude; what order of magnitude is important? A 20mph wind exerts something on the order of 80 pascals (about 0.01psi), if my math is correct. The membrane likely stops enough air movement, at that magnitude, to be "considered airtight". So, yeah, science!

[simclardy]

So i bought an old house, 1865 on cape cod. I have been in the trades for 20 years. I am very interested in this discussion. Especially comparing old with new. I keep finding reasons to go back to the "old" method. Example, i reroofed with cedar shakes instead of asfault due to ecological concerns and discovered they reflect radiant heat better and provide better it is breathable.
Another example. wool socks vs high tech water wicking plastic socks:( no competition. Alpaca socks rock in the winter. So my next project is walls. Do i use sheetrock or stay with plaster? I would love to hear more. I feel like sheetrock is hygroscopic and would force me to use ac? Cheers

[jorgeantelohollweg]

Lot to learn everyday. I watched twice to fully understand. Thanks Corbett!!

[Sub-Zero-Homes]

I think we would all agree that a glass beaker is both air and water tight. And if we put some water in it this will prove to be the case. However, if we poured Superfluid liquid helium in there it would leak through the glass. Now, we are taught that in order for a liquid to escape a container air must be able to get in otherwise we have the vacuum effect. So if we sealed the top of the glass beaker, then what would happen?

Superfluid liquid helium.
The chemical element helium exists in a liquid form only at the extremely low temperature of -269 degrees Celsius, very close to absolute zero. watch?v=9FudzqfpLLs Search for it and you can see liquid helium running through a solid glass beaker. This is because the liquid has such little viscosity that it runs through the gaps in the beaker at a molecular level, so if you try to pour it into a glass container it will simply run straight through it.

I think the reason things don't pass through other things even though most of it is empty space and in theory they so easily could is because of energy/heat. Things are not just molecules sitting there completely still, they are bouncing around and this prevents things passing through other things depending on how much energy it has. Radiation has very high energy and passes through anything. Which is the reverse of the above experience where it was super cooled to make it a liquid and possibly reduce its activity allowing it to pass through a glass beaker.

[markn]

Sounds like the equating of knowledge to a lightbulb. The more you know equates to a bulb becoming brighter. Which leads to a larger sphere of darkness or what you don't know.

[emish]

What barrier would you recommend if i have foam in your stud bays before the drywall or shiplap? I also don't want moisture to get trapped between my exterior tyvek and my internal membrane, i have heard that condensation can occur between those two layers.

[ajbeck]

Hey bro, I like that poster. Where can I find 1?

[aimkevtadok]

Hope Matt Risinger end up on this Video ;)

[lgmnowkondo]

the one on the left has a serious rack...and a brain....nice!

[markbowman]

Nothing is 100% OR perfect. Does that mean we do not strive for it. Thank you for your input, but give credit to the people moving forward and working on solutions. You made it sound like, Give up you can’t get