Ultimate Guide To Spray Foam Insulation Terms

You're reading about spray foam insulation and keep running into terms you don't understand. Not only are you frustrated, but you feel like you aren't learning anything.

South Central Services has installed spray foam in hundreds of homes. We walk through these terms with our clients every week. To help you keep learning, we have compiled a glossary of these technical terms.

By the end of this article, you will understand the key terms related to spray foam insulation and building science.

Above-Grade

Above-grade means above the ground. In construction, above-grade refers to any part of a building at or above ground level.

Adhesion

Adhesion refers to spray foam insulation sticking to the surface it was sprayed against (substrate). If spray foam does not adhere, it cannot offer an airtight seal. Adhesion issues cause a gap between the substrate and the insulation, compromising effectiveness.

Air Barrier

An air barrier refers to creating an airtight seal. With an air barrier, air cannot infiltrate through gaps or cracks in a building envelope. Open and closed cell spray foam insulation can create an air barrier.

Air Infiltration

Air infiltration is the leakage of unconditioned air through gaps in a building envelope. Through air sealing, air infiltration can be prevented.

Assembly

An assembly refers to the building materials that create part of a building. Examples include a roof assembly, wall assembly, or floor assembly. Depending on the goal of an assembly, it can feature many different materials. A wall assembly may include drywall, insulation, wood, foam, wrap, and siding.

A-Side

A-Side is one of two chemical components that create spray foam insulation through a chemical reaction. A-Side is the conversational name for isocyanate.

B-Side

B-Side is one of two chemical components that create spray foam insulation through a chemical reaction. B-Side is the conversational name for polyol blend.

Band Boards

A basement band board is the transition from a masonry basement wall to wood floor joists. Band boards are also called rim joists. As the meeting point for basement walls and ceilings, band boards are usually insulated as part of the walls or ceiling.

Batting

Batting is a style of insulation. Batting could be fiberglass, rockwool, or cotton. Batting is cut ahead to fit a particular size cavity, like a wall cavity. Batting is not always sized to the cavity it is filling. Improperly sized batting creates gaps and compromises the effectiveness of the insulation.

Below-Grade

Below-grade means below the ground. In construction, this refers to any part of a building below ground level.

Blower Door Test

Blower door tests measure air leakage in a building. A professional uses a fan to change the air pressure inside the building, then measures how much air leaks inside (or outside) the building in an hour. The results are represented in air changes per hour (ACH).

Board Foot

A board foot is a three-dimensional measurement of length, width, and depth. While a square foot only measures length and width (1 foot by 1 foot), a board foot also accounts for depth (1 foot by 1 foot by 1 inch). Board feet are the measurement that spray foam contractors use to create quotes and calculate the cost of insulating with spray foam.

Building Envelope

The building envelope refers to the outer shell of a building that separates the interior conditioned space from the external environment. The building envelope helps to protect and regulate the indoor environment.

Can Foam

Can foam is a type of urethane foam. While spray foam is a two-component foam (polyurethane), can foam is most commonly a single-component foam. Can foam is sold at home improvement stores for a variety of purposes, including cracks, window frames, door frames, pest control, and outdoor use. Can foam is one of the five types of foam insulation for residential use.

Closed Cell Foam

Closed cell foam is one of two types of spray polyurethane foam (SPF). Closed cell foam is the more dense of these foams, with a closed cell structure. You can compare the cell structure to a foam board, which cannot easily be compressed and has no visible air pockets.

Conduction Heat

With conduction, heat travels through a solid material. Picture heating a pot of water on the stove. The burner element is the heat source. Heat conducts through a metal pan to heat the water. Traditionally, insulation materials are concerned with preventing conduction heat. Materials that do not conduct heat well are considered good insulators, and can prevent heat transfer through conduction as the sun beats against walls and roofs.

Convection Heat

With convection, heat is transferred through the air. Hot air rises, and cold air sinks. Picture a tray of cookies baking in an oven. Convection ovens cook food by circulating air and its heat around the food. Traditional insulation materials cannot prevent convection heat from altering indoor temperatures because they do not create an air barrier. Spray foam can create an air barrier and help avoid heat through convection.

Curing

Curing refers to the process which transforms liquid spray foam components into a solid, fully hardened state. During application, the foam undergoes a chemical reaction that causes it to expand, fill gaps, and eventually solidify. The curing process cools the foam, creating a durable, stable, and effective insulation barrier. Curing is the final step of the process to create spray foam insulation.

Density

Density is one of the distinguishing features between open cell and closed cell spray foam. Open cell spray foam is a flexible, low-density foam. Closed cell spray foam is a rigid, higher-density foam. Density determines ideal applications and other features of these foams.

Dew Point

Think of the air as a sponge that can only hold a certain amount of water. Dew point is the temperature where the air is saturated with water and cannot hold any more. Like a dripping sponge, the water vapor in the air condenses into liquid water. Warm air can hold more water vapor than cold air, which is why Pennsylvania summer days can feel either sticky or dry. It depends on the humidity content in the air. Dew point is essential in construction because it determines the vapor barrier needs in different climate zones.

Encapsulation

In construction, encapsulation refers to enclosing a portion of a building to join it with the building envelope. Crawl spaces are the most frequently encapsulated area of a building. To encapsulate a crawl space, a vapor barrier is installed on the floor and walls. The crawl space ceiling is left uninsulated, as the encapsulated crawl space joins the conditioned space of the rest of the home. Attics can also be encapsulated.

Energy Efficiency

Energy efficiency refers to the energy use of a building. For a building to be comfortable, it needs to use energy. An energy-efficient building uses less energy to provide the same amount of comfort and performance.

Fire Resistance

The only fire-proof building materials are noncombustible materials like glass or rock. Any combustible building material must be tested for fire resistance. Flammable building materials can resist spreading fire and developing smoke through added chemical treatments. Read more about flammability and fire safety of spray foam insulation.

Flashing

Flashing refers to a protective component or material used to prevent water or moisture intrusion at vulnerable areas of a building envelope. It is typically installed around openings like windows, doors, and roof penetrations to direct water away from these areas. Flashing acts as a barrier, ensuring that water doesn't seep into the insulation or the underlying structure and safeguarding against potential moisture damage.

Flash and Batt

Flash and batt is a hybrid insulation method that combines spray foam and batt insulation. This method most commonly refers to an inch of closed cell spray foam with a fiberglass batt. Spray foam is used for its air-sealing ability and higher R-value. The batt insulation layer is less expensive and can offer some sound attenuation. South Central Services does not install traditional flash and batt insulation. Instead, we offer a hybrid system.

Flood-Resistant

Flood-resistance refers to a material's ability to protect itself from water damage in the case of a flood. A flood-resistant product is not waterproof and cannot protect any other materials from water damage. Closed cell spray foam is the only insulation that is classified as a flood damage-resistant material by the Federal Emergency Management Agency.

Injection Foam

Injection foam is a three-component insulation made of water, resin, and a foaming agent. Spray foam and injection foam are different kinds of foam insulation. Injection foam can only be installed by contractors with injection foam equipment. The main purpose of injection foam is to insulate the exterior walls of existing homes.

Isocyanate

Isocyanate is one of two chemical components that create spray foam insulation through a chemical reaction. A-Side is the conversational name for isocyanate.

Open Cell Foam

Open cell foam is one of two types of spray polyurethane foam (SPF). Open cell foam is the less dense foam with an open cell structure. The cell structure can be compared to a yellow car wash sponge, which can be compressed and has visible air pockets.

Off-Gassing

Off-gassing is a byproduct of a chemical reaction. For spray foam insulation, off-gassing occurs during the manufacturing process. These off-gassing fumes must be directed outside of the building using ventilation. Contractors installing spray foam wear respirators to protect their lungs from these fumes.

Off-Ratio Foam

Off-ratio foam refers to spray polyurethane foam which has some amount of one chemical leftover which did not react to create foam. This type of foam is a result of equipment failure. Off-ratio is not a safe or inert product and should never be left as a finished product.

On-Ratio Foam

On-ratio foam refers to spray polyurethane foam where all chemicals have reacted to create foam. When installed within manufacturer guidelines, on-ratio foam is a safe and inert finished insulation product.

Personal Protective Equipment (PPE)

Personal protective equipment (PPE) is any clothes, equipment, or accessories worn to protect people from job hazards. Common examples include safety glasses, masks, and gloves.

For spray foam insulation contractors, PPE includes eye protection, respirators, masks, and disposable coveralls.

Polyurethane Foam

Polyurethane foam is a type of plastic foam. At a chemistry level, polyurethane foam is made of polymers linked by urethane.

Polyol Blend

Polyol blend is one of two chemical components that create spray foam insulation through a chemical reaction. B-Side is the conversational name for polyol blend.

Radiant Heat

With radiation, heat travels as visible and invisible light. Instead of warming the air around us, radiant heat directly warms things like the floor, walls, or objects in a room.

Retrofitting

Retrofitting refers to upgrading or modifying an existing structure or system to improve its functionality, efficiency, or performance. It involves making changes or additions to accommodate new technologies, enhance energy efficiency, meet updated building codes, or address specific needs without completely rebuilding.

Rim Joist

In a basement, a rim joist is the transition from a masonry basement wall to wood floor joists. Rim joists are also called band boards. As the joint between the basement walls and the basement ceiling, rim joists are usually insulated as part of the walls or ceiling.

R-Value

R-value, or resistance value, measures how well a material resists heat transfer. Materials with a low R-value have low heat resistance and conduct heat effectively. Materials with a high R-value have a high heat resistance and conduct heat poorly. Insulation products should have higher R-values because the insulation is supposed to conduct heat poorly and resist thermal transfer. R-value is measured per inch.

Sound Attenuation

Sound attenuation is the process of quieting the volume and distinctness of sounds as they pass through a material. Sound attenuation and soundproofing are not the same thing. With sound attenuation, you may hear sounds. However, these sounds will be muffled and indistinct.

Sound Dampening

Sound dampening refers to reducing or suppressing sound vibrations or noise transmission. It involves using materials or techniques that absorb, block, or reduce the intensity of sound waves. Sound dampening aims to minimize the impact of noise and create a quieter environment by employing sound-absorbing materials, adding insulation, or creating barriers. Sound dampening could occur within a room or between different areas or structures.

SPF (Spray Polyurethane Foam)

SPF is the abbreviation for spray polyurethane foam. Spray polyurethane foam is created from a chemical reaction between isocyanate and polyol blend. Spray polyurethane foam is manufactured and installed on-site to be used as insulation. There are two types of spray polyurethane foam: closed cell and open cell.

Spray Foam Rig

A spray foam rig is a truck or trailer that houses spray foam equipment. These rigs travel to job sites, transport spray foam components, and monitor the spray foam chemical reaction. A spray foam rig could cost as much as $100,000 for a professional contractor to create.

Substrate

Substrate is a construction term for surface. To install spray foam against a substrate is to spray the product against a surface. Any surface where spray foam can be installed is an example of a substrate.

Thermal Barrier

In construction, a thermal barrier is a physical material that creates a barrier between the potential fire and the building envelope. An example is drywall. Building codes determine thermal barriers and are usually measured in time. A building code may require a fifteen-minute thermal barrier, equivalent to a half-inch of drywall.

Thermal Bridging

Thermal bridging is the phenomenon where heat flows more easily through certain pathways or materials in a building's envelope, bypassing insulation. When gaps occur in insulation, an increased amount of heat transfers in these areas. These thermal bridges can lead to energy loss, reduced insulation effectiveness, and potential condensation issues.

Thermal Conductivity

Thermal conductivity refers to the ability of a material to conduct heat. It measures how well a material allows heat to pass through it. Materials with high thermal conductivity, like metals, are efficient at transferring heat. Materials with low thermal conductivity, such as insulation materials, are better at resisting heat flow and providing thermal insulation.

Underslab

Underslab is applying insulation beneath the concrete slab of a building's foundation or floor. Spray foam insulation is installed directly onto the ground surface before pouring the concrete slab on top. The underslab insulation helps to create a thermal barrier, preventing heat loss or gain through the foundation and improving energy efficiency within the building.

Vapor Barrier

A vapor barrier is a material's ability to prevent moisture in the air from passing through a wall, roof, or ceiling assembly. Vapor barriers stop outside humidity from coming inside and prevent inside moisture from entering the building envelope. Closed cell spray foam can create a vapor barrier, while open cell spray foam cannot.

Vapor Retarder

A vapor retarder is added to a material to help create a vapor barrier. For open cell spray foam, vapor retarder coatings can be added. Paper facings are added to act as a vapor retarder for fiberglass batt insulation. Another example of a vapor retarder is latex paint on your walls.

Ventilation

There are three types of ventilation: air infiltration, natural ventilation, and mechanical ventilation. Ventilation is necessary to exchange stale inside air with fresh outside air. Air infiltration is uncontrolled and can introduce outdoor air pollution to indoor air. Recommended ventilation for buildings includes natural and mechanical ventilation. An example of natural ventilation is opening a window. An example of mechanical ventilation is an HVAC system.

Yield

Yield refers to how much output is generated from an input. For spray foam insulation, yield measures the difference between the raw chemical inputs and the finished foam output. Closed cell spray foam has a smaller yield than open cell. If we start with the same amount of raw chemical components, less finished closed cell and more finished open cell foam product would be generated.

The Bottom Line About Spray Foam Insulation Terminology

Truly understanding insulation requires understanding many building science terms. As you do more research, consult this glossary for a refresher on confusing terms. You can also use this as a guide for conversing with insulation contractors to help you determine how educated they are about building science and insulation.

Want to learn more about spray foam and building science? Check out these articles.

• Does Spray Foam Insulation Make a House Too Airtight?
• Why Is Air Sealing a Home Important?
• Can Spray Foam Insulation Fail?