The main component which gives structure to your home is the walls. In wood
frame construction, the weight of the roof, shingles, Standing rain water, the weight of the
roof, snow, and shingles all add weight to the roof on wood construction, which results in a
compressive force to the walls from exerting downward forces.
Imposing lateral forces on the walls of the homes are created from gusts and
high winds from storms. A "shearing force" can be generated by the lateral forces that distort
To be able to withstand these forces and loads, a home's walls are required by
building codes to be designed in a certain way. Walls are nevertheless sometimes built to the
minimum standards, so sounds of creaking and shaking that are created through movement or during
high winds can often be heard.
To reinforce both the studs and the exterior sheathing inside the walls, higher
density closed-cell spray foam is recommended, for it adheres fully to both. There will be less
wall movement due to vibration, wind, and occupant activity with the added rigidity that
closed-cell spray foam provides. "Racking events" such as hurricanes or high wind situations can
also be avoided with closed-cell SPF because your walls will have greater resistance than what
is required by building code.
Adding structural strength to the building is another benefit of an SPF
application. SPF filled walls could add from 75% to 200% racking strength to walls of vinyl
siding, gypsum board, light gauge metal, or OSB plywood, as NAHB Research has demonstrated.
A wall can change from its original rectangle shape into a parallelogram due to
shearing forces. Engineers tend to use a "racking test" in order to test a wall's resistance to
the shear forces imposed by wind loading. In order to do so, a model wall that is 8 ft. x 8ft.
is placed in a large frame after being constructed. Then, a horizontal (lateral) force is
applied at one upper corner of the wall while the base remains secured to the frame. The force
is increased until the wall structure fails, with constant 400 lb. increments added throughout
The Added Strength Effect of Spray Foam on the Wall
Walls with spray-applied polyurethane foam insulation and without were compared
in a series of racking tests. These racking tests evaluated two exterior facing materials:
1. Plywood textured siding
2. 15-lb. building paper with vinyl siding on top of it.
The interior side of all the wall panels used 16-inch stud spacing and it was
faced with half-inch sheetrock The stud cavities of the wall panels that were insulated with
spray-applied polyurethane foam were filled with 1.5 lb/ft^3 foam density.
The stud walls that were filled with spray-applied polyurethane foam add
significant strength to the home walls, as the graph indicates. The foam filled walls also
deformed less with each load that was applied, and, additionally, the walls offered greater
Spray-applied polyurethane foam insulation was compared with conventional R-19
fiberglass batts during a second series of racking tests. The wall panels were faced with
drywall on both sides during one comparison, and the wall panels were faced with drywall on one
side and OSB (oriented strand board) on the opposite side during another. The average foam
density used was 2.26 lb/ft3 and the wall panel used steel studs spaced 24 inches on center in
The graph indicates once again that the spray foam insulated wall system had
Test results are reported in "Testing and Adoption of Spray Polyurethane Foam for Wood Frame
Building Construction" (May 25, 1992) prepared by NAHB Research Center for The Society of
the Plastics Industry/Polyurethane Foam Contractors Division.
Test results are reported in a letter from Bob Dewey, Mechanical Engineer, NAHB Research
Center to Mason Knowles, The Society of the Plastics Industry/Spray Polyurethane Foam
Division (November 18, 1996).
What can spray foam do for your Texas home or building?
Empire Spray Foam is conveniently located in North Texas and proudly serves the Tarrant, Dallas,
Denton, Wise, Parker, Hood, Johnson, Ellis, Kaufman, Rockwall, and Collin Counties with high
quality spray foam and coatings designed to meet the needs of homeowners and businesses. Whether
you are looking for energy savings, structural reinforcement, or weatherproofing, we have the
solution. Call today to discuss your spray polyurethane foam options 817-516-2014.
Empire Spray Foam, LLC | Phone: 817-516-2014 | Company Headquarters: 5008 Vesta Farley Road, Fort Worth, TX 76119