7 Minutes of BS (#BuildingScience w/a BEAT)

Vapor Permeance

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."

Radiant Barriers

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.

Makeup Air

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

Roof Ventilation

Roof Ventilation by ProTradeCraft.com

Reservoir Claddings and Mass Walls

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.

Mechanical Ventilation

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

Efflorescence

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

Thermal Bridging

Building science with a beat

Stack Effect

Stack effect is relentless: it is always working, when you’re awake or asleep, even during blackouts. And it feeds on itself.

Ice Dams

A big problem, for roofs in cold climates, but what causes it and how can you fix it?