Unvented attics have been designed and constructed for some 30 years. They are referred to by various names, including conditioned attics, semi-conditioned attics, indirectly conditioned attics, hot roofs, and compact roofs.

In Canada, products approved for use as a thermal barrier for foamed plastic must pass either CAN4-S124-M, Standard Method of Test for the Evaluation of Protective Coverings for Foamed Plastics, or CAN/ULC-S101, Standard Methods...

For decades, designers of attics and crawlspaces have used cross-ventilation to minimize potential for moisture accumulation and condensation. However, spurred by recent claims of energy savings and moisture control, unvented attics have become popular...