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SWH Solar Racking Installation Guide | Version 12.10.v2
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[2.1.] Using Standard Beam Calculations, Structural Engineering
Methodology
ASCE 7-10
Step 4: Select Rail Type
Step 5: Determine the Downforce Point Load, R (lbs),
at each connection based on rail span
R (lbs) = PLB/2
R = Point Load (lbs)
P = Total Design Load (psf)
L = Rail Span (ft)
B = Module Length Perpendicular to Rails (ft)
It is the installer’s responsibility to verify that the building
structure is strong enough to support the maximum point
loads calculated according to Step 5.
Total Design Load (downforce) (max of case 1, 2 or 3):
P
B
L
R
psf
ft
ft
lbs
Step 1
Step 3
Module length perpendicular to rails:
Rail Span:
Downforce Point Load:
Table 8. Downforce Point Load Calculation
It is the installer’s responsibility to
verify that the building structure is
strong enough to support the point
load forces.
Selecting a span and rail type affects the
price of your installation. Longer spans
produce fewer wall or roof penetrations.
However, longer spans create higher point
load forces on the building structure. A
point load force is the amount of force
transferred to the building structure at each
connection.
When designing the SWH Flush Mount Installation, you
must consider the downforce Point Load, R (lbs) on the
roof structure.
The Downforce, Point Load, R (lbs), is determined by
multiplying the Total Design Load, P (psf),
(Step 1)
by
the Rail Span, L (ft)
(Step 3)
and the Module Length
Perpendicular to the Rails, B (ft) divided by two.
t
x
x
/2
