When the outdoor air temperature swings from hot to cold, a building’s insulation regulates the temperature inside. The heating and cooling system of a well-insulated building doesn’t have to work as hard - and that results in cost and energy savings for you. Insulation also provides thermal comfort and protection from extreme weather.
Life-safety and energy-efficiency are why building codes, often modified by state code officials to be climate-specific, require that plans for a construction project demonstrate that the proposed insulation for exterior components - roof, walls, foundation - will achieve specific R-values before a building permit is issued. If you’re not familiar with R-values, they indicate how well insulation resists heat loss. The higher the R-value, the better the insulation.
Many types of insulation are available, made from different materials and with different methods of application. Understanding the advantages and disadvantages of each type helps builders, architects, and homeowners make the best choices for their project. Two common types of insulation are rigid foam board and spray foam.
So, how do you decide between them?
Rigid Foam Board Insulation: High R-Values Per Inch
Rigid foam board insulation is foam plastic that has been hardened and formed into sheets that are easy to cut on site. Most rigid foam boards are made from one of three types of plastics: polystyrene, polyisocyanurate (polyiso), and polyurethane.
Rigid foam insulation offers very high R-values per inch of thickness. This becomes important during the project’s design phase when the team is figuring out how to insulate the structure to meet R-values required by the building code. Rigid board insulation increases the wall assembly’s R-value without a significant increase in the overall thickness of the wall. If you want to maximize interior space, keeping the exterior wall thickness to a minimum is essential.
Spray Foam Insulation: Expands to Fill Any Space
Spray foam insulation also offers extremely high R-values. Most often made from liquid polyurethane and a foaming agent, spray foam insulation is applied using a spray can for small cracks and air leaks, or blown in with a pressure-sprayer for larger applications (referred to as “foamed-in-place”). The liquid foam expands and hardens as the material cures. Because its shape conforms to the space in which it is applied, spray foam provides an effective air barrier and is excellent for use in hard-to-reach places, and curved or irregular spaces.
The two types of spray foam are open cell and closed cell. Open cell is lighter and more pliant with foam bubbles that expand, burst, and fill with air. Closed cell is much denser and durable; its cellular structure is closed and filled with gas.
Rigid Foam and Spray Foam: Installation is the Key Difference
Rigid foam boards and spray foam insulation are installed using completely different methods, which informs the decision of which product to choose.
Because it can be sprayed on, blown in, or poured, spray foam insulation is frequently used in retrofits and remodels to fill in existing wall cavities and awkward spaces like attics, where other types of insulation might be difficult or impossible to install. Spray foam’s high R-value makes it a good choice when an existing wall or roof cavity needs to be brought into energy code compliance.
Rigid foam boards are cut to fit and then mechanically attached to the structure. Often seen in new construction, rigid foam boards can be used to insulate just about any part of the building from foundation to roof. They’re commonly part of exterior wall assemblies, including below-grade walls. Some rigid insulation boards are made specifically to be exposed on interior walls of structures like parking garages or farm buildings. Others are manufactured with air and water barriers on one side, eliminating the need to buy and install additional products.
Advantages of Rigid Board Insulation
Cost
Rigid foam insulation boards are less expensive to install than spray foam. Special equipment and certified installers are typically required to install spray foam insulation.
Thermal Performance
Rigid insulation boards are installed continuously over the studs preventing thermal bridging and heat loss.
Ease of Installation
Rigid foam can be cut to fit on site, and attached to roof or wall structure. When multi-functional boards with integral air and water barriers are used, additional time and money is saved.
Basement Insulation
Rigid foam boards are very well-suited for insulating basement walls as they are water-resistant and easily installed by adhering them to the foundation walls behind the studs.
Rmax Rigid Foam Insulation Boards
Rmax is a leading manufacturer of polyiso rigid foam insulation boards with a variety of products to suit any insulation need. If you decide that rigid foam insulation boards are the right choice for your project, Rmax is happy to provide more information and answer any of your questions. Contact the experts at Rmax today.