DESlGN/INSULATlON
Materials
There are a variety of materials used as thermal insulation, each with advantages and
disadvantages in application within particular envelope systems. The Insulation Contractors
Association of America (ICAA) manual describes the various types of insulation and provides the
relevant specifications for each. Most of the material in this section is based on this document as
well as Chapter 20 of the ASHRAE Handbook of Fundamentals, Thermal Insulation and Vapor
Retarders - Fundamentals and Brand. Additional information on the various insulation materials
and systems is available from the relevant industry associations listed in the Appendix C of these
guidelines.
Insulation materials used in commercial construction include inorganic fibrous and cellular materials
such as glass and rock wool, perlite and vermiculite. Organic fibrous and cellular materials are also
used, such as cellulose, foamed rubber, polystyrene, polyurethane and other polymers. Metallic or
metallized organic reflective membranes are also available, and are used as radiant barriers with air
or gas-filled spaces. Insulation materials are available in a variety of forms including loose-fill,
flexible and semi-rigid, rigid and foamed-in-place. All insulation materials have advantages and
disadvantages, and their application must be considered with regard to issues of thermal
resistance, degradation over time, shrinkage or settling, compatibility with adhesives and other
proximate materials, and environmental concerns of recycling and offgassing.
Batt or blanket type mineral insulation is often used in stud walls for heat and sound control, and to
be effective it must completely fill the cavity being insulated. When installing this insulation, the
pieces should be as long as possible to minimize end joints, and where they do occur the material
should be butted tightly together to avoid gaps. The batt should extend the full height of the cavity,
butting flush at the top and bottom, again to avoid any gaps. When the batt is held by friction, it
must be slightly oversized to prevent sagging and the associated gaps. When the cavity is more
than about 2.5 m (8 feet) high, or it does not completely fill the cavity, additional mechanical
attachment is necessary. Various mechanical fasteners are available, but it is important that they
do not compress the insulation.
Insulation is also available in rigid boards consisting of mineral fibers, extruded polystyrene,
expanded polystyrene, polyurethane, polyisocyanurate and light-weight cementitious composite
materials. Mineral fibers boards should not be held up with adhesive alone since the fibers tend to
come loose at the point of contact; some means of mechanical attachment is required. Mineral
boards are advantageous when applied to rough surfaces, such as concrete masonry, because
they are flexible enough to conform to the surface without leaving air spaces between the insulation
and the backup. Rigid plastic boards have the advantage of rigidity and greater thermal resistance
per thickness. They can be held in place mechanically or with adhesives. When rigid board
insulation is applied in a cavity, the design must account for the exposure of the insulation to water.
The insulation boards themselves should not be considered as a waterproofing material; a separate
waterproofing system is required.
Various materials are available in the form of sprayed insulation, including mineral fibers, cellulose
and foamed plastics. Sprayed insulation can be used in a variety of applications including exterior
walls and can provide continuous coverage that is free of voids and cracks. When using sprayed
insulation, there are several important jobsite issues to be considered, including proper preparation
of the surface to receive the insulation, job scheduling to avoid damage to the completed work and
temperature conditions at the time of the installation. Some spray insulation materials, including
foamed plastics, can provide an air and water tight barrier. The insulation may need to be
supplemented by flexible seals at interfaces between envelope components in order to
accommodate differential movements.
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