Unvented Unvented cathedral Unvented Unvented cathedral cathedral - PowerPoint PPT Presentation

Unvented Unvented cathedral Unvented Unvented cathedral cathedral roof cathedral roof roof roof by y interior y interior

Unvented Roof Unvented Roof ‐ Studies Studies Figure 10: Air Impermeable Spray Foam Insulation Figure 11: Unvented Flat Roof Assembly – High Density Spray Foam • In Climate Zones 5 or higher a Class II vapor retarder is required on the • High density spray foam insulation does not require an interior vapor interior of the spray foam layer. retarder in any climate • If a high density foam is used in this assembly, a Class II vapor retarder • Membrane, metal, and shingle roofs can experience night sky cooling that is not required in Climate Zones 5 or higher as the high density foam can depress roof deck temperatures significantly below ambient air itself qualifies as a Class II vapor retarder. temperatures. When membrane roofs and asphalt shingles are used it is typically necessary install rigid insulation above the roof deck or install air • A thermal barrier is required to separate spray foams from occupiable impermeable insulation below the roof deck. spaces due to the fire performance of spray foam insulations spaces due to the fire performance of spray foam insulations. Joseph Lstiburek, « Undertanding attic ventilation », Building Science digest 102

Cathedral Cathedral roof roof unvented unvented Retrofit or complex roof, No space to ventilate (old construction)

FLAT ROOF UNVENTED FLAT ROOF UNVENTED 75mm 75mm

CASE STUDY CASE STUDY

TEMPERATURE OF SHINGLES AND MEMBRANE TEMPERATURE OF SHINGLES AND MEMBRANE LECTURES TEMPERATURES OF THE MEMBRANE TEMPERATURES OF THE MEMBRANE TYPES OF BLACK GREY WHITE PVC "ENERGY SURFACES SMART" Temp. surface 180°F 157°F 128°F 108°F F F Temp. surface 82°C 69°C 53°C 42°C C

CATHEDRAL ROOF CATHEDRAL ROOF HOW IS IS VENTED? No venting Joseph Lstiburek, « Builder’s Guide », Building Science Corporation, 1998

STRUCTURE DETAIL STRUCTURE DETAIL Joseph Lstiburek, « Builder’s Guide », Building Science Corporation, 1998

CATHEDRAL ROOF CATHEDRAL ROOF VENTED VENTED BY OUTSIDE BY OUTSIDE BY OUTSIDE BY OUTSIDE

FLAT ROOF VENTED FLAT ROOF VENTED 75mm SPRAYED BY EXTERIOR SPRAYED BY EXTERIOR– – RETROFIT RETROFIT

VENTED CATHDRAL ROOF VENTED CATHDRAL ROOF KNEE WALL CATHEDRAL KNEE WALL CATHEDRAL VENTED VENTED VENTED VENTED VENTED CATHEDRAL VENTED CATHEDRAL VENTED CATHEDRAL VENTED CATHEDRAL

CANTILIVERED CANTILIVERED FLOOR FLOOR

CMHC CONSTRUCTION GUIDE CMHC CONSTRUCTION GUIDE

ROOM OVER GARAGE ROOM OVER GARAGE

CMHC CONSTRUCTION GUIDE CMHC CONSTRUCTION GUIDE