The intent of this guide is to educate designers, construction professionals, and building developers on best practice enclosure design principles for mass timber enclosures, including roofs, walls, and floor/soffit conditions. Version 2 of this guide includes expanded discussion on fire protection, examples of higher-performing enclosure systems, and design discussion for balcony assemblies. Additionally, new photos and illustrations are provided throughout the guide. This guide is a compilation of new and previously published content authored by RDH Building Science; resources used to compile this document are included in the references and additional resources sections of this guide. This guide is a companion to Moisture Risk Management Strategies for Mass Timber Buildings, also published by RDH Building Science.