GreenBuildingAdvisor - Building Science

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In our last episode, Dr. John talked about How Heat Moves Through Homes and why radiant barriers work better in outer space than on earth.

In this episode, Dr. John talks about the history of insulation, how different materials work, and where they make sense.

TRANSCRIPT
The history of insulation comes about because of the history of structural engineering. Now, I’m a recovering structural engineer, which is probably why I like to think of it that way.

Podcast NID:  History of Insulation

Subtitle:  To avoid moisture problems in walls, think about the permeability of all the wall’s components — not just the “designated” vapor retarder Images: 

Today’s walls, roofs, and floors are better insulated, tighter, and made with a much greater variety of components than they used to be, making them a lot more susceptible to moisture problems when they get wet. Compared to the old days, today's walls and ceilings are more complicated and can be very slow to dry.

Subtitle:  Solar degradation of lignin at wood’s surface is the single most important factor affecting the weathering of wood and subsequent paint adhesion Images: 

The weathering of wood is very different from decay; weathering is breakdown at the surface only. While there are a number of forces that contribute to weathering of wood—moisture, temperature, abrasion by wind-borne particles, air pollution—it’s the narrow band of high-energy ultraviolet light in sunlight that is the dominant force (see Image #1).

What bare wood looks like when cut or milled