building envelope
GOAL: an envelope that keeps a building warm in winter, cool in summer, sheds moisture, and exceeds structural, fire, and acoustic requirements.
Important to understand: U-Value (the inverse of the American R-Value):
The lower the U-Value of your building envelope is, the better it is able to insulate you from climatic extremes. With a better-insulating envelope, measures need to be taken to keep air quality at it’s best, which is where ventilation strategies come in.
One of the most common errors in building envelope design is trapping moisture inside an envelope. This can happen many ways: building with improperly dried wood, trapping wood between two impermeable membranes, or convection through voids (this is why we pressure-test buildings now).
When these risks aren’t mitigated during the planning (or worse, construction) of a building, the ramifications can be career-ending. Growing up during the "Leaky Condo Crisis" of the 90s made for a constant reminder of the consequences of ignoring these facts.
It boils down to this: in our climate, the moisture that forms through normal and predictable building physics must be able to diffuse quickly and uninhibited towards the outside of the envelope. Everything else plays second fiddle.
Local fire codes will dictate which materials you may or may not use, depending on the type of project you have planned.