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April 7, 2022

TCL Episode #53 – A Real Science Guy – Greg Labbe from the Ryerson Building Science Research Lab

Show Notes

Greg Labbe, a chemistry guy who started in big pharma, quality control, and also worked in the mining sector. He was not meant to do bench work so he joined a small company that did home energy audits called Greensaver. He worked 12 years over there managing spray foam, retrofit and has assessed thousands of houses, so 20 years ago, he left the job and started his own consulting firm.

According to Greg, what’s the point of making things look pretty if they are not working properly or are not 100% functional as they should be. He prefers on knowing what’s happening behind the bricks, or behind the drywall. He is now managing Building Science Research Lab at Ryerson and he has students (PhDs and graduates) who are doing research on bricks, foam, caulking, etc.

Disconnect is the real issue!

When asked Greg about what’s wrong in modern building science, he replied that when diagnostics are done on buildings, it is found that most of the buildings are based on an air barrier system that is not fully integrated. He says the issue arises in the transition of the air barrier system, the junctions are usually done wrong, and you find condensation or degradation. The issue is usually in the rim plates, and ledger plates around the home, it’s never thermally broken, and it’s never airtight.

So, in other words, the disconnect is the real issue, it’s a trade issue. You have separate trades on the job site, every trade handling separate details of the time, and they are not working together consider creating a unified system (home). He also explained how theory is not just enough, and how we need more journeypeople on the job site, instead of apprentices.

Envelope seal better from Outside

Is an envelope seal better from the inside or from the outside? Greg replied that it’s certainly easier to get a better air seal when you’re doing it from the outside. It is because the electrical boxes and plumbing penetrations on the outside are about 1/10th of the ones they have inside. And so, it’s easy to put your air barrier on the outside. When your envelope doesn’t perform, the system cannot keep up.

Pink Insulation – Why still in?

Greg explains the reasons pink insulation is still in

  1. Quantity
  2. Price
  3. It attenuates sound better than fiberglass.

All about Spray foam!

Greg is a Cufca-certified spray former. He believes that one needs a strong arm like a horse to spray form, and he doesn’t have one as he gets older. Greg says that it is a great product in a basement, it’s great for a cathedral roof where you’re bonding the foam to the inside face of sheathing. He explained that spray foam is pushed out through a gun that has tiny little holes, and it should be cleaned properly, as things might get off-ratio. If you want it to cure right with minimum off-gas, make sure that temperature is key, and it should not go off-ratio. It’s an occupational hazard and can lead to severe sensitivity, so make sure that you’ve got fresh air.

Greg says that his issue with spray foam in a stud cavity is if you are using it as an air barrier system, your sheathing, your drywall, or your OSB it should be taped because that’s the most continuous layer. It should act as a zip system and be taped exteriorly.

Greg also discussed how a company is making a spray foam with zero global warming potential. As spray foams mostly use the chlorinated molecules to expand and create the little bubble. And that bubble, it stays in there. But the problem is that this bubble releases slowly over time and it gets into the atmosphere, and it can lead to ozone depletion.


In the basement, the first pass is one continuous layer of foam. And that one continuous layer behaves like a system, and then you can layer on top of that you could peroxyly wherever you want that base system is there. Let’s go up the wall.

Now we’re above grade, main floor. So, two by six, we’ve got sheathing, so why not just use the sheathing as the air barrier, you can tape it, that becomes your air barrier. You can spray foam on the inside and have a continuous layer on the outside whatever board foam you want to use.

And now moving up towards the cathedral roof. The one thing about a hot roof is that you should have the foam bonded to your sheathing. You can’t have a gap. If you’ve got an air gap back there, the air will find a way to get back there. And the air serves as a conveyor belt that will move moisture in and out. Usually, if it’s moisture air from the outside, it’s no big deal, but usually what happens is moisture-laden air from the inside eventually gets into those cracks. In theory, it should get ventilated but usually, it deposits all its moisture.

Is Spray Foam Toxic?

Greg explained that because of the formaldehyde, spray foams are toxic. The choice is to either scrape it all out or install a ventilation system like an HRV to dilute the pollution. Greg uses polyurethane foam which when installed properly is not toxic. However, it is bad for the people installing it within 30 seconds. Though the off-gassing can be hazardous for 24 to 72 hours, Greg explained how the chemical off-gas is way too much in the first 15-20 minutes.

Vapor vs Air Barriers

Greg also gave us a better understanding of vapor and air barriers. He said that the materials matter when this discussion comes. For example, a six-mil poly, can serve as both an air barrier and a vapor barrier. Suppose we have a piece of Tyvek. It is vapor open and it can be part of the air barriers system as well. So, no air will actually go through it, but the vapor moisture can go through it. If we consider membranes like Gore-Tex, it is vapor open and is also breathable, and it is also waterproof. And that’s a big distinction, different materials have different properties, that have single purposes when they’re by themselves, but when they’re connected to a system, the properties change. So, when they are contributing to the whole system, their functionality might change based on the climate and other conditions. For example, a six-mil poly is sometimes just a vapor control layer.

Other Takeaways

  • Carlito shared his technique when he lay tile, he cuts out a 24 by 24 piece of plastic. He red tapes it to the ground and comes back the next day to see how much moisture is caught up underneath.
  • The first two years after building a house, the moisture is insane. Everything in the house, e.g., concrete is drying out and curing and has a lot of moisture.
  • People pay to get balanced ventilation.
  • The building code changed a couple of years ago. Now you have to install an HRV.
  • Plants or big green wall is just a compilation of mold in the house. They are not used for air purification or air movement, in fact, they promote mold growth in the house.
  • If you want to make a change in this industry you have to test your work. Testing buildings for air leakage is one way to get buildings a little bit more efficient. Greg says that nothing beats finding people who care and who are just are willing to go an extra mile to bring efficiency in their work, and betterment in the industry.

Take out your pencil and paper, and hear the podcast to learn more about building science from the science guy Grey on the episode!