"You can't simply go down to the hardware store and buy a box labeled air barrier."

This episode features Jonathan Smegal, M.A. SC a Senior Project Manager with RDH Building Science Laboratories breaking down the topic of air barriers in walls and roofs.

"A layer in the enclosure that stops the air movement from the interior to the exterior, and it often requires many components that are put together to make a durable continuous air barrier system."

In this episode, we are joined by Sarah Gray, an engineer with RDH Building Science Inc. to talk about using simple physics to outthink simple physics.

Using gravity to beat surface tension, and slope to beat gravity.

Vapor permeance is the property of a material – and in our discussions this will be building materials – which permits the passage of water vapor through it.

Today's guest is Jonathan Smegal of RDH Building Science Laboratories...

Some materials have high vapor permeance which means they allow a lot of water vapor to pass and other materials have significantly less vapor permeance, so they block water vapor movement and these are called vapor barriers or vapor retarders."

Thin foil can block massive amounts of heat transfer, but it needs a massive temperature difference to be effective. So, in residential construction, thermal insulation makes radiant barriers largely irrelevant.

Houses cannot expand and contract with changes in pressure like balloons can. Instead, they need paths for air to balance the pressure

Roof Ventilation by ProTradeCraft.com

Guest: Sarah Gray, P. Eng., RDH Building Science Inc.

Reservoir claddings include brick, stone, terra cotta, and even stucco, that are all porous materials. When exposed to rain or vapor diffusion, those pores will absorb and hold water until, the pores dry out. Just like a dam holds back lake water, the damned bricks hold the rain.

Exhaust, supply, balanced, and backdrafting. How to visualize what you cannot see.

Physics vs physical structures and how salt can blow apart brick.

Building science with a beat