Air control material

A material that has sufficiently low air permeance and adequate strength that it can be part of an air control layer system. Examples: gypsum board, plywood/OSB, foam board, duct board (with a facing flame spread rating of 25 or less), sheet metal or dimensional lumber. Recommended maximum air permeance for an Air Control Material is 0.02 l/(s m2) @ 75 Pa (0.004 cfm/ft2 @ 0.3" WC) when tested according to ASTM E 2178 or E 283.

Air-impermeable material

Air permeance equal to or less than 0.02 l/s m2 @ 75 Pa (0.004 cfm/ft2 @ 0.3" WC) when tested according to ASTM E 2178 or E 283.

Aluminum coil stock

Aluminum coil stock, as used in this guide, refers to thin aluminum metal sheet that is coated to resist corrosion and suitable for forming into various shapes on a metal brake or a roller-extrusion die. Aluminum coil stock is typically manufactured in rolls or "coils".

Bituminuous membrane

A self-adhered membrane composed of rubberized asphalt adhesive; typical material has a polyethylene facer, and is vapor impermeable.

Building paper

Also known as "tar paper," asphalt-saturated Kraft paper, or asphalt- impregnated cellulose fiber; a paper (cellulose fiber) and asphalt-based drainage plane or water control layer.

Butyl membrane

A self-adhered membrane based on synthetic rubber (elastomer); typical material has a polyethylene facer, and is vapor impermeable. Butyl rubber adhesives (as opposed to asphalt) typically have fewer chemical compatibility issues than asphalt-based adhered membranes.

Closed-cell spray foam insulation

Spray-applied foam insulation where the cured foam is of predominantly closed cell structure. Characterized by low vapor permeability. Density is generally between 1.5 and 2.5 lb. per cubic foot. The typical range for R-value is 5.6 - 6.3 depending on product and installation. Vapor permeance is less than 1 at approximately 2" thickness or greater.

Dampproofing

A coating, typically asphaltic, that is applied to a foundation wall and that significantly reduces or totally prevents the wall surface from wicking water from the soil. Although typically marketed as "water proofing" the more reliable function of these coatings is preventing capillary transfer (wicking) to the foundation wall surface. Dampproofing is typically not able to withstand significant hydrostatic head pressure, which makes the use of drainage very critical.

Dense-packed fibrous insulation

Fibrous insulation that is installed to a non-settling density, usually 3-4 lb/ft3. Although dense-packed fibrous insulation cannot be used as an air control material it typically does inhibit airflow through cavities.

Dimple mat

A plastic sheet that is formed with uniform protruding dimples to one side to allow the dimple mat to create a uniform separation between the surface of the dimples and the surface of the sheet. A dimple mat also provides a compressive strength of at least 10 psi / 10% deflection. Most commonly used to establish a drainage space between soil and below-ground structures, dimple mats can also be used to create a drainage space between layers of built assembly such as in the case of the slab retrofit assembly illustrated in this guide. Because of the continuous nature of the plastic sheet, a dimple mat can also be used to establish a water, air or vapor control layer

Drainage mesh

A non-moisture sensitive material that has an open structure allowing the passage of liquid water and that provides a compressive strength of at least 10 psi / 10% deflection. Its application is similar to that of a dimple mat with the exception that a drainage mesh does not, without a top sheet, provide resistance to water, air or vapor flow.

Epoxy paint or coating

A durable paint or coating that is capable of resisting hydrostatic pressure and vapor pressure

Expanded polystyrene (EPS)

A foam plastic insulation material formed of styrene beads expanded in a mold. EPS is produced to differing properties according to the recognized types of EPS. Type I EPS is most common but also the lowest recognized density, thermal resistance and compressive strength of the recognized EPS types. Because of its poor compressive and flexural strength, Type I EPS is not recommended for use as insulating sheathing or as a rigid board insulation. Type II EPS is suitable in some conditions for use as an insulating sheathing and as rigid board insulation. Type II EPS has a minimum compressive strength of 15 psi and a minimum thermal resistance of R-3.5 per inch. EPS is not suitable for ground contact or applications where it is subject to immersion in water.

Extruded polystyrene (XPS)

A foam plastic insulation material formed by extruding foamed styrene through a die. XPS is generally stronger, has greater thermal resistance and is less vapor permeable than EPS. Typical thermal resistance ranges from R-5 to R-5.6 per inch depending on manufacturer and specific product.

Flashing tape

A thin flexible membrane strip with contact or pressure sensitive adhesive. Both the membrane strip and adhesive must be impervious to water.

Flashing membrane

A flexible membrane that is impervious to water.

Foil-faced polyisocyanurate

Polyisocyanurate insulation board material with foil facing laminated to both sides. The foil facing provides dimensional and shape stability to the polyisocyanurate insulation boards. Foil-faced polyisocyanurate board typically has a greater R-value than other types of polyisocyanurate insulation board material and is also vapor impermeable (less than 0.1 perm). For some foil-faced polyisocyanurate insulation board products, the foil facing is intended as a finish, in other products, the facing contributes to the ignition barrier of the foam.

Free-draining backfill

A back fill material that provides very little resistance to the movement of water by gravity.

Fully-adhered membrane/material

A flexible film or sheet building material that is adhered to or incorporated with its substrate in a continuous manner. The membrane bridges minor gaps and cracks. A fully-adhered membrane may be a peel-and-stick type membrane or a liquid applied membrane.

Fully-adhered air control membrane

An air control membrane that is adhered to or incorporated with its substrate in a continuous manner. It must be durable and capable of withstanding pressures and minor building movement to which it would be subject in operation.

Fully-adhered water control membrane

A water control membrane that is adhered to or incorporated with its substrate in a continuous manner. It must be durable and capable of withstanding pressures and minor building movement to which it would be subject in operation.

Furring strip (or vertical furring strip)

A strip of material having uniform thickness used to create a uniform separation between a cladding or finish material and substrate. A furring strip also typically provides an attachment structure for the cladding or finish material.

Housewrap

Any of the numerous artificial polymer rolled sheet goods designed to function as drainage planes, a class of sheathing membranes. Some are also used as part of an air barrier system. Can be made of spun-fiber polyolefin, perforated plastic films, or coated and micro-perforated polymers. Housewraps made of visibly perforated (macroscopic hole) plastic films are not recommended.

Insulating sheathing

Non-structural insulating board products with varying R-values and a wide variation in vapor permeability and drainage characteristics. Materials include expanded polystyrene (EPS) excluding Type I, extruded polystyrene (XPS), polyisocyanurate, rigid fiberglass, and mineral wool.

Insulation

Any material which significantly slows down or retards the flow or transfer of heat. Building insulation types are classified according to form (e.g., loose- fill, batt, flexible, rigid, reflective, and foamed-in-place) or material (fiber glass, rock and slag wool, organic fiber, foam plastic).

Installed R-value

A metric commonly referenced in building codes and used by industry. This is simply the R-value labeled on the product installed in the assembly.

Loose-fill fibrous insulation

Fibrous insulation material that is installed with blower equipment or poured in place.

Liquid-applied air control membrane/material

See fully-adhered air control membrane above.

Low expansion foam sealant

A foam sealant that has been engineered to cure with minimal expansion and minimal expansive force.

Mastic

Heavy-consistency compound that may remain adhesive and pliable with age. Typically an airtight, waterproof compound that is applied to exterior walls and roof surfaces or used to provide a robust and durable air seal to air duct distribution systems.

Non-moisture-sensitive material

A material that is not degraded by prolonged contact with liquid state water. Most, but not all, plastics are non-moisture-sensitive materials. EPS and polyisocyanurate foam insulations are somewhat moisture sensitive and should not be used in applications were they will be subject to extreme vapor pressures, submersion in water or ground contact. Wood materials remain water sensitive regardless of treatment.

Open-cell spray foam insulation

Spray-applied foam insulation where the cured foam is of predominantly open cell structure. Characterized by high vapor permeability - 6-29 perms at 3" thickness, 4-18 perms at 5" thickness. Density is generally between

0.5 and 1.0 lb per cubic foot. Typical R-value ranges from 3.8 to 4.0 per inch depending on product and installation.

Polyisocyanurate

A closed-cell foam insulation material typically sold in rigid boards. R-value can range from R-5.6 to R-6.5 per inch, depending on the manufacturer, the age of the foam, and the presence or absence of foil facings. Polyisocyanurate is somewhat moisture-sensitive and not suitable for installation in ground contact or where it is subject to immersion in water.

Rigid Board Insulation

See insulating sheathing above.

Rigid Foam

Rigid board material that provides thermal resistance and compressive strength of 15 psi at 10% deformation. Examples include foam plastic insulation such as EPS (excluding Type I), XPS, and polyisocyanurate.

Roof Underlayment

The materials installed beneath roof cladding capable of protecting the cladding substrate from liquid water. At the perimeter of the roof, at valleys, penetrations, and wall-roof intersections, the underlayment must be a self-sealing ice and water control membrane. In the field of the roof, away from edges, valley, penetrations and intersections with walls, the roof underlayment may be an ice and water control membrane, roofing felt, or an engineered roof wrap.

Sealant

Any flexible product which when applied to the join of two or more materials will adhere and permanently seal the joint to the passage of air. Examples: caulk, foam, and mastic. Within the construction industry, the use of the term to describe products is regulated (Relevant test methods: For foam sealants

- ASTM C1642; for acrylic, silicone, and urethane caulk - ASTM C-920).

Self-adhered water control membrane

See fully-adhered water control membrane above.

Self-adhered air control membrane

See fully-adhered air control membrane above.

Self-sealing ice and water control membrane

A membrane capable of maintaining air and water tightness around installed fasteners that penetrate the membrane. It must be noted that self- sealing membranes typically do not self-seal over a hole left by a fastener that has penetrated the membrane then, subsequently been removed. Self- sealing membranes typically include bituminous or butyl compositions.

Semi-rigid mineral fiber insulation

A type of insulation that is sold in formed boards composed of mineral fibers (typically fiberglass or rock wool). Normally used for its non- combustible properties.

Sheathing tape

A thin film tape usually with an acrylic adhesive that is compatible with the sheathing material used.

Sill pan flashing

A flashing that covers the bottom of a window or door opening and that includes end dams to either side of the opening as well as a back dam (toward the inside) and/or slope to the exterior.

Spray Foam Insulation

See closed-cell spray foam insulation and open-cell spray foam insulation above.

Tape

In this guide "tape" designates a durable thin film strip with a durable adhesive that is compatible with the substrate materials.

Vapor impermeable

Describes materials with a permeance of 0.1 perm or less (e.g. rubber membrane, polyethylene film, glass, aluminum foil).

Vapor permeable

Describes materials with a permeance greater than 10 perms (e.g. most housewraps, building papers).

Vapor semi-impermeable

Describes materials with a permeance of 1.0 perm or less and greater than

0.1 perm (e.g. oil-based paints, most vinyl coverings)

Vapor semi-permeable

Describes materials with a permeance of 10 or less and greater than 1.0 perm (e.g. plywood, OSB, most latex-based paints).