The area inside a SIP building envelope is considered conditioned space and will be ventilated by the building’s HVAC system. There is no need to provide a vented attic beneath a SIP roof, and doing so would compromise the conditioned space of the building.
Research conducted by Building Science Corporation on test homes in hot climates demonstrates that including the attic in the conditioned space allowed for more energy-efficient space conditioning and less probability of moisture related issues. [Rudd, Armin and Joseph Lstiburek. Vented and Sealed Attics in Hot Climates. Building Science Press, 1998]
Some building science experts recommend venting the roof by providing an air space between the SIP roof panels and the roofing material (known as a “cold roof”). This practice is not a requirement for SIP buildings, but an extra measure to improve the durability and moisture resistance of the building.