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Building Science Fundamentals Workshop taught by Joe Lstiburek – A Recap

Last month, members of the Ziger/Snead team attended the Building Science Fundamentals Workshop led by Joe Lstiburek.

Joe is an acknowledged expert and often a forensic witness in court cases involving failures in building construction. His two-day workshop is a deep dive into how professionals involved in designing and constructing buildings need to understand the physics of air and water; the materials used in modern construction and how the order of these in the wall/roof/foundation assembly are critical.

During the workshop, we learned that the first two questions you must answer when designing the building environmental separation are:

  1. Where are you in the world? What is the external environmental load? Locality matters. There is a big difference between hot and humid Florida and cold and dry Minnesota.
  2. What is in the building? What is the internal environmental load? How the building is used matters.


For Senior Associate, Darragh Brady, it was understanding how differently we build and condition buildings now versus in the past. We used to build solid, thick masonry buildings which allowed moisture to move both ways through the assembly and we put enough energy into our buildings to dry/dehumidify them if there was too much moisture. Now we build out of layers of easily damaged light weight or hollow materials, some of which are permeable to moisture and some of which are not. In addition, we try hard to limit the amount of energy we use to heat or cool a building, so there is much less energy to ‘dry’ the building. If you reduce the drying potential you must reduce the wetting potential.

It has always been true that ALL buildings leak and construction isn’t perfect. The difference now is that we must control the movement of water, air and vapor through the environmental separation and understand the complexities of the materials we are using.


- Not a lot happens in the field of a wall: it all happens at the holes, the corners, and the parapet.
- Any building with AC in a remotely humid climate should not have a vapor barrier on the inside of the wall.
- Don’t be a dope, slope!
- Vapor - one water molecule - golf ball - can have building wraps that are hydrophobic but vapor permeable.Water- 75 to 150 molecules – basketball vs. golf ball

- Definition of a problem: you must have at least one of the following
- People
- Pollutant (hot, wet, UV, ozone)
- Path
- Pressure

Get rid of any one of these and you get rid of the problem. For example, you solve mold problems by solving water problems.

- Do not trust test and balance reports, they only measure flows not pressure. These reports can be inaccurate, therefore it is best to measure the pressure directly.

- If you smell vomit in a building you know there are wet ceiling tiles. If you smell dirty socks, check air handlers. Acoustical insulation when it gets wet smells like dirty socks!

- If your spray foam is crunchy, gooey or smells like dead fish it has been installed incorrectly.