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Why should I worry about wall strength?
Your walls are the main
structural component of your home. In wood frame
construction, the weight of the roof and any snow on
the roof push down on the walls with a compressive
force. Strong winds and wind gusts impose lateral
loads onto your house walls that tend to distort the
walls with a shearing force. Building codes require
that walls be designed to withstand these loads.
However, when walls are built to minimum standards,
while safe, you may sense wall creaking during high
winds or shaking when doors are slammed or the kids
are actively romping about.
What is a shearing force?
A shearing force on a wall tends to distort
the wall from it’s original shape as a rectangle
into a parallelogram. To test a wall’s resistance to
the shear forces imposed by wind loading, engineers
use a “racking test.” An 8 ft. x 8 ft. model wall is
built and placed in a large frame. The base of the
wall is secured to the frame and a horizontal
(lateral) force is applied at one upper corner. The
force in increased in 400 lb. increments until the
wall structure fails.
What is the effect of All Tech Insulation on wall
strength?
In a series of
racking tests*, walls with and without spray-applied
polyurethane foam insulation were compared. Two
exterior facing materials were tested:
(1) Vinyl siding over 15-lb. building paper;
and
(2) 5/8- inch textured plywood siding.
All wall panels were faced with 1/2-inch
sheetrock on the interior side and used 16 inch stud
spacing. For the stud wall panels that were
insulated with spray-applied polyurethane foam, the
stud cavities were essentially completely filled
with foam of 1.5 lb/ft3 density.
As the graph indicates, stud walls filled with
spray-applied polyurethane foam add significant
strength to home walls. Furthermore, for each load
applied, the foam filled walls deformed less and
offered greater resilience.
What does this mean to me?
All Tech Insulation Foam is sprayed into your stud
walls and fully adheres to the exterior sheathing
and studs, reinforcing both. With this added
rigidity, there will be less wall movement due to
shaking and vibration. Additionally your walls have
greater than code required resistance to “racking
events” such as hurricanes or other strong wind
situations.
PDF Brochure of Wall Strength(
249 k)
Contact an All Tech Insulation
engineer today (989-826-9999) for a deeper discussion
about your insulation requirements.
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