Roxul ComfortBoard IS - Manual (Page 6)

4 ROXUL
® The Better Insulation™
Building Science for COMFORTBOARD IS Walls
A functional overview of the building enclosure
The building enclosure is defined as the physical component of a building that separates the interior
environment from the exterior environment: it is an environmental separator. In general, the physical
function of environmental separation can be further grouped into three useful sub-categories as follows:
1. Support, i.e., to support, resist, transfer and otherwise accommodate all structural loading
imposed by the interior and exterior environments, by the enclosure, and by the building itself.
The enclosure, or portions of it, can sometimes be an integral part of the building superstructure
either by design or in actual performance.
2. Control, i.e., to control, block, regulate and/or moderate all the loadings due to the separation
of the interior and exterior environments. This largely means the flow of mass (rain, air, water
vapor, pollutants, etc.) and energy (heat, sound, fire, light, etc.).
3. Finish, i.e., to finish the surfaces at the interface of the enclosure with the interior and exterior
environments. Each of the two interfaces must meet the relevant visual, aesthetic, durability
and other performance requirements.
Control and support functions must continue across every penetration, every interface and every
assembly. The lack of this continuity is the cause of the vast majority of enclosure performance problems.
For physical performance, the most common required enclosure control functions include resistance to:
rain penetration, air flow, heat transfer, condensation, fire & smoke propagation, sound and light
transmission (including view, solar heat, and daylight), insect infestation and particulate penetration, and
human access. As these functions are required everywhere, continuity of these control functions,
especially at penetrations, connections and interfaces between materials, is critical to a successful
enclosure.
The most important control function with respect to durability is rain control followed by air control,
thermal control, and vapor control. The level of fire and sound control required varies with code
requirements and owner requirements. This guide will provide recommendations for residential wall
construction with insulating sheathing for rain control, air control, thermal control, and vapor control.