Page 28 - November 2015 Green Builder Magazine

The Homeowner’s Handbook SIXTH EDITION

Lightweight Glossary of Terms
Concrete Blocks
Know the Lingo

26 ■■ Dimensional Lumber: Wood that has been cut and shaped

from a single tree, typically used for framing.

■■ Load-Bearing Wall: A wall that helps hold up the house.
Interior walls may not be load bearing, but external ones
almost always are.

■■ Engineered Wood Products (EWP): Structural
products made in the factory from industrial wood scrap
or fast-growing species, assembled with resins under
extreme pressure.

■■ Oriented Strand Board (OSB): A type of engineered
wood panel. The thickness of OSB used in most
SIPs is 7/16”.

■■ Fly Ash: Controversial waste by-product from coal-fired
power plants. Used as a filler in some—but not all—brands
of lightweight concrete blocks.

■■ Sound Transmission Class (STC): Refers to how well
a wall partition attenuates sound. Products such as ICFs
have high STC ratings and greatly reduce noise levels
inside the home.

www.greenbuildermag.com 11.2015 Virtues Caveats LIGHTWEIGHT CONCRETE BLOCKS
Lasting Value
■■ Easy to handle ■■ May not be locally manufactured
Lightweight concrete is a structural material that’s been around
■■ Less energy intensive ■■ Contractors/masons since at least the 1920s. To create these blocks, the manufacturer
than concrete may need training replaces a portion of the concrete with something lighter and
better insulating, such as an industrial waste product like fly
■■ Durable and termite proof ■■ Waste components ash or petroleum-based polystyrene. Some companies such as
should be tested/verified Cresco Concrete, creator of Liteblok (www.crescoconcrete.com)
use a temporary agent that leaves nothing but air gaps behind.
INSULATING CONCRETE FORMS If a product does include fly ash, make sure the manufacturer
Light and Tight provides data showing that they have carefully tested and
screened the material to keep heavy metals and other toxins
Poured concrete walls alone have very little insulating value. Yet out of the end product.
concrete can last forever, or nearly so, if it’s protected from erratic
moisture changes and freeze-thaw cycles. That’s what makes STRUCTURAL INSULATED PANELS
ICFs an excellent structural system. They enclose both sides of Many Strengths
a poured cement wall within a water-resistant cocoon of rigid
foam. Another advantage to ICFs is that their assembly is quite The concept here is simple. Two sturdy panels—typically
simple, and the completed walls have an average insulating value oriented strand board (OSB)—are glued under pressure to a super
of about R-22. insulating layer of plastic-based rigid foam (either polystyrene

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