Insulation

greater resistance to air and water vapor flows. Because the closed-cell foam is denser it
requires more material and thus expenses. Closed-cell foam is recommended for use over
open-cell below grade, especially in conditions of high water tables.
Spray polyurethane foam seals the entire building envelope of the home to prevent air
and moisture infiltration. Specifically polyurethane maintains a permanent shape and will
not sag or deform. In addition, it adds strength to the building structure. Lateral
movement by strong winds and storms create shearing forces on the home. Foam
insulation is monolithic and capable of reducing racking and shearing. Closed-cell spray
foam reinforces rigidity of the studs and sheathing.
In terms of installation and application, the foam is formed by trapping many gas forms
into a liquid or solid. One of the most popular foam insulations is polyurethane. It
contains polyol (a petroleum product), a surfactant, and a catalyst (to control reaction
rate). The size of the bubbles differs based on reaction rate and it dictates the density of
the foam product. Roofing foam must be denser than wall foam for higher strength. The
bubbles come from a blowing agent which is a liquid with a low boiling point, which is
capable of producing pockets of a gas. The last ingredient is isocyanate, which is highly
reactive. Isocyanate is separated from all components until dispensed through the hose
gun. Once it hits the substrate it drives the expansion reaction very quickly. Spray foam
insulation is applied to walls with an 80% pass. A downside to spray foam insulation is it
requires a skilled installer to prevent overspray.
Spray polyurethane foam has an R-value of approximately 6.0-7.0 per inch, depending on
formulation. This R-value is significantly higher than glass fiber, wool, and cellulose
insulations. It is adequate for residential, commercial, and industrial buildings. Spray
Polyurethane Foam provides more thermal resistance with less material than any other
commercial insulation material. It has a fairly low sound transmission coefficient of 37.
Spray polyurethane foam costs roughly $1.25-$2.25 per square foot. It forms to walls,
floors, and roofs as a tight seal, stopping air leakage as well as moisture infiltration.
Traditional fiberglass insulation stapled or placed into wall cavities does not seal the stud
and wall cavities, and gaps remain. For homes with crawl spaces and basements, high
humidity brings trouble for standard fiberglass insulation. Fiberglass absorbs moisture; it
may get heavy and fall from sub-flooring. Spray foam contractors are often hired to
remove old and wet fiberglass, and use spray foam as replacement. Spray foam maintains
its physical properties over time.
Oftentimes, no additional vapor barrier is required when using Spray Polyurethane Foam,
saving an additional item cost. Performance studies in the field suggest Spray
Polyurethane Foam systems used for roofing can last thirty or more years. Walls have a
longer lifetime exists due to its lack of exposure. Spray foam insulation increases a
home’s energy performance, structural integrity and air quality; and is increasingly used
to insulate walls, basements, and attics of homes.
Hurricane Katrina destroyed the original roof of the Superdome in New Orleans and
caused $250 million in damages to the structure. The state of Louisiana demanded a roof