Planning glossary
R-value
A measure of thermal resistance under stated conditions; a product label is not the same as whole-assembly performance.
Example
Framing can bridge around cavity insulation, reducing the wall's overall thermal resistance.
Related concepts
Thermal bridge
A more conductive path through or around insulation that changes whole-assembly heat flow.
Read definitionEnclosure
The connected layers that separate indoor and outdoor conditions, including water, air, vapor, and thermal control decisions.
Read definitionAssembly
A defined combination of layers, components, and rules that turns geometry into a building element or quantity recipe.
Read definitionUse the term in context
Definition boundaryThis planning definition is not a substitute for the definition in an adopted code, standard, contract, manufacturer instruction, or professional document. Confirm the controlling meaning for the project.