Glossary of building termsUpdated 2 months ago

Glossary of useful building terms

With all the building jargon and terminology out there, it can be intimidating to even start a conversation about insulation.

With that in mind, we put together our list of key insulation terms to help you make more informed decisions.

Insulation Terms

R-value measures how well insulation resists heat flow. The higher the R-value, the better it insulates your space.

Thermal bridging is when outside temperatures are transferred inside and vice versa. Think of a structural metal beam that runs from the outside to the interior. When that beam transports cold air (in winter) to the inside of the structure, that is thermal bridging.

Air-tightness is how well a building keeps outside air from leaking in. The tighter the seal, the more efficient the home.

A convective loop is the cycle of air inside a room resulting in heat loss. When warm air rises and cool air sinks, it creates a cycle that can make a room lose heat.

Wind washing is when wind pushes air through walls or insulation, making your home drafty and sometimes causing condensation.

Vapor drive is when moisture moves through walls, which can lead to condensation inside your home.

Types of Insulation

Batts are precut insulation designed to fit into specific cavities.

Loose-fill (also referred to as Blown-in) is a blown application generally seen to reduce the potential for gaps in cavities. Most commonly used for attics

Facing (or face) is a covering applied to one side of insulation. Popular with fiberglass.

Vapor barrier is any material (typically a plastic film) used to resist the diffusion of moisture

Insulation Metrics

R-Value (again) measures how well insulation resists heat flow. The higher the R-value, the better it insulates your space.

Flame spread and smoke development measure resistance to flame and how much smoke is developed. Most insulation conforms to Class A of the building code by adding toxic flame retardants.  Wool is naturally self-extinguishing.  

Sound transmission coefficient (STC) is a rating scale used to measure how well an entire wall system (with multiple layers) blocks sound.

Noise reduction coefficient (NRC) measures how well a single material absorbs sound

WUFI is the measure of an insulation’s ability to manage moisture.

Building Terms

Joists are lengths of timber (or steel,etc) arranged in parallel to support floors or ceilings.

Studs are vertical framing pieces, usually wood and typically 2×4 or 2×6 measured at 16 or 24” on center.

Furring strips are wood or other material used to level a surface or bump out a cavity so that  insulation can be installed.

Rim joists attach perpendicularly to the joists providing support for the ends of the joists while capping off the end of the floor.

On-Center (O/C) is the measurement from the center of one stud to the center of another stud.

Eaves are the part of the roof that overhangs a wall.

Soffit vents are vents in a soffit (underside of an eave) that allows fresh air into an attic.

Baffles are chutes that channel from soffit vents into attic space. This helps reduce moisture in your attic.

Attic vents are placed on a roof to allow air flow.

A ridge vent is installed at the peak of a roof to allow air flow in an attic.