Issue:
DS2013 – 053 by Jared Cejka of Pella Windows &
Doors. The Petitioner requests
clarification with regard to the appropriate approach for comparing the design
pressure for his product to that of the building.
Background:
Situation
#1:
Pella Corporation is a manufacturer of windows and
doors, and distributes Florida Approved products through retail locations in
the state of Florida. The scenario in
which the Declaratory Statement is sought involves a customer of one of Pella’s
distributors. The contractor has
purchased a Florida Approved Single-Hung
window; and as with all of Pella’s products, this window has a design
pressure that has been tested to and is based on allowable/nominal design
loads. As indicated by ASCE/SEI 7-10,
the testing requirements for fenestration products based on allowable stress
design loads has not changed. However,
the calculations used to determine a home’s design pressures now results in
pressures based on strength design loads; thus, a conversion must be made to
the home’s pressures in order to properly compare the product to the
structure. According to Building Code
Section 1609.1.5, this section states that since the product has been tested
for wind load resistance based on allowable or nominal wind loads; the design
loads for the structure that are determined in accordance with ASCE/SEI 7-10
and are based on strength design loads must by multiplied by a factor of 0.6
for appropriate product to structure comparison.
2010
Florida Building Code, Building
Section 1609.1.5 Testing to
allowable or nominal loads.
Where testing for wind load resistance is based on
allowable or nominal wind loads, the design wind loads determined in accordance
with ASCE 7 or Section 1609 are permitted to be multiplied by 0.6 for the
purposes of the wind load resistance testing.
Situation
#2:
The contractor has a Florida Approved Pella single-hung window that has a
design pressure based on allowable stress design. This window is being installed in a residential
home opening that has a design pressure that has been determined in accordance
with ASCE/SEI 7-10; the pressure is based on strength design loads. Utilizing the table from the Residential Code
Section R301.2.2 for this opening, and following the rows/columns for design
wind speed, wall zone, and effective wind area; you are provided with a design
pressure that is based on an ultimate design wind load.
Florida
Building Code, Residential
TABLE R301.2 (2) COMPONENT AND CLADDING LOADS FOR A
BUILDING WITH A MEAN
ROOF HEIGHT
OF 30 FEET LOCATED IN EXPOSURE B (See attached)
R301.2.1.7
Testing to allowable or nominal loads.
Where
testing for wind load resistance is based on allowable or nominal wind loads,
the design wind loads determined in accordance with ASCE 7 or Section 1609 of
the Florida Building Code, Building are permitted to be multiplied by 0.6 for
the purposes of the wind load resistance testing.
R612.5
Performance.
Exterior
windows and doors shall be designed to resist the design wind loads specified
in Table R301.2 (2) adjusted for height and exposure per Table R301.2 (3). For
testing required in Sections R612.6, R612.7, and R612.8, design pressures
determined from Table R301.2(2) or ASCE 7 are permitted to be multiplied by
0.6.
Staff
Recommendation: