Wind-Rated Roofs - Panelized Structures, Inc.

Wind-Rated Roofs
DESIGNING COMMERCIAL ROOFS
TO WITHSTAND WIND UPLIFT FORCES
Wind-Rated Roofs
WOOD
The Natural Choice
Engineered wood products are a good choice for the environment.
They are manufactured for years of trouble-free, dependable use. They
help reduce waste by decreasing disposal costs and product damage.
Wood is a renewable, recyclable, biodegradable resource that is easily
manufactured into a variety of viable products.
A few facts about wood.
We’re growing more wood every day. Forests fully cover one-third
of the United States’ and one-half of Canada’s land mass. American
landowners plant more than two billion trees every year. In addition,
millions of trees seed naturally. The forest products industry, which
comprises about 15 percent of forestland ownership, is responsible for
41 percent of replanted forest acreage. That works out to more than one billion trees a
year, or about three million trees planted every day. This high rate of replanting accounts
for the fact that each year, 27 percent more timber is grown than is harvested. Canada’s
replanting record shows a fourfold increase in the number of trees planted between 1975
and 1990.
■
Life Cycle Assessment shows wood is the greenest building product.
A 2004 Consortium for Research on Renewable Industrial Materials
(CORRIM) study gave scientific validation to the strength of wood as
a green building product. In examining building products’ life cycles
– from extraction of the raw material to demolition of the building at the
end of its long lifespan – CORRIM found that wood was better for the environment than
steel or concrete in terms of embodied energy, global warming potential, air emissions,
water emissions and solid waste production. For the complete details of the report, visit
www.CORRIM.org.
■
Ma nufa c t ur i ng wo o d i s e n e rg y
efficient. Wood products made up 47
percent of all industrial raw materials
manufactured in the United States,
yet consumed only 4 percent of the
energy needed to manufacture all
industrial raw materials, according to
a 1987 study.
■
Material
Wood
Percent of
Production
Percent of
Energy Use
47  4
Steel23
48
Aluminum 2  8
Good news for a healthy planet. For every ton of wood grown, a
young forest produces 1.07 tons of oxygen and absorbs 1.47 tons of
carbon dioxide.
■
Wood: It’s the natural choice for the environment, for design and for
strong, lasting construction.
Form No. G310
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© 2006 APA – The Engineered Wood Association
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www.apawood.org
Wind-Rated Roofs
T
he roof system is an integral part of any
CONTENTS
structure, but designing and building commercial
Introduction . . . . . . . . . . . . . . .   3
roofs for wind uplift resistance is particularly
Wind Uplift Ratings . . . . . . . . . .   4
crucial in coastal and other high-wind areas. Many
Wood Structural Panel
Benefits . . . . . . . . . . . . . . . . . . . .   5
insurance companies require roof systems to be rated
UL Roof Assemblies . . . . . . . . . . .   5
for wind uplift resistance before they will insure the
FM Approvals-Tested
Roof Assemblies . . . . . . . . . . . .   7
building.
For More Information . . . . . . . 11
This publication from APA – The Engineered Wood
About APA . . . . . . . . . . . . . . . . . . . 12
Association provides assembly details for roof
systems with APA wood structural panels used as
the substrate. Each assembly contains a classification
based on Underwriters Laboratories or FM Approvals
testing that determines the maximum wind uplift the
roof system can resist. By following the classifications
required by the region in which the structure is built,
commercial designers and builders can ensure wind
uplift resistance and meet insurance requirements.
For additional information on wind uplift or roof
design or for assistance with specific design problems,
contact the APA Product Support Help Desk at (253)
620-7400 or help@apawood.org, or visit our web site
at www.apawood.org.
Form No. G310
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© 2006 APA – The Engineered Wood Association
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www.apawood.org
Wind-Rated Roofs
Wind Uplift Ratings
Wind uplift-resistance ratings are based on a roofing system’s performance in wind uplift tests. Underwriters
Laboratories (UL) and FM Approvals (Factory Mutual or FM) are two agencies that do research and testing and assign
wind uplift classifications that buildings must often meet to be insured. Because of the assemblies’ structural merits,
many commercial designers use UL or FM rated systems even when not required to do so.
UL assigns systems a semi-wind-resistive classification (Class 30 or 60) or fully-wind-resistive classification (Class 90).
FM assigns systems Class 1 ratings based on the wind uplift pressure (not wind speeds) in pounds per square foot (psf)
that the system resisted during testing, e.g., 1-90 or 1-105.
In 2004, APA participated in FM Approvals testing directed by the Asphalt Roofing Manufacturers Association (ARMA).
APA designed the wood structural panel decking systems, and APA members provided plywood and oriented strand
board (OSB) panels used for these tests over wood bases. FM conducted tests to evaluate the capability of the deck
components of the roofing system to resist a minimum simulated wind uplift pressure for one minute. Tests began with
30 psf of pressure, with pressure increasing in increments of 15 psf after each minute of successful resistance until failure occurred in any component. FM assigned systems classifications based on the last successful one-minute pressure
resistance, meaning a system that failed during the 135 psf pressure test would receive a 1-120 class rating.
It is important to note that a safety factor of two is required nationwide to receive FM insurance coverage on any building. Thus, to be insured in an area with wind loads of up to 45 psf, the structure’s roof system must be built to a 1-90
classi­fication. Many fire-rated wood roof assemblies can also qualify for wind uplift ratings. Tables 1 and 2 make a simplified comparison between the wind speeds, as shown in Figure 1609 of the 2003 International Building Code (IBC)
and the design corner uplift pressures given in Table 1609.6.2.1(2) of the IBC.
tABLE 2
tABLE 1
pRESSURES(1)
wIND sPEEDS AND
Maximum WindRoof Corner Uplift
Velocity (mph,Design PressureRequired
(psf)FM Rating
3 second gust)
85
33
1-75
90
37
1-75
100
45
1-90
110
55
1-120
120
65
1-135
Minimum Wood StructuraL Panel
Requirements for Panelized Roof Systems
(Panel Strength Axis Parallel to Supports)(1)
Minimum Panel
FM
Thickness (in.)Additional
Class(2)
and Span Rating Requirements
B, enclosed structure, Zone 3 of a flat roof,
height 30 feet.
(1) Exposure
1-60
15/32 – 32/16
5-Ply Plywood or OSB
1-75
15/32 – 32/16
5-Ply Plywood or OSB
1-90
19/32 – 40/20
4-Ply Plywood or OSB
1-105
19/32 – 40/20
5-Ply Plywood or OSB
1-120
19/32 – 40/20
5-Ply Plywood or OSB
1-135
19/32 – 40/20
5-Ply Plywood or OSB
(1) Minimum
thickness is critical due to fastener holding requirements. For additional cross-panel strength, stiffness and
fastener-holding capacity without additional thickness, specify
APA Structural I Rated Sheathing.
(2) Based on roof corner uplift design pressures from the IBC and
ASCE 7-05 for Enclosed, Exposure B and roof height 30 feet.
Form No. G310
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© 2006 APA – The Engineered Wood Association
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www.apawood.org
Wind-Rated Roofs
Wood Structural Panel Benefits
Wood structural panels provide a solid substrate to which the built-up or modified bitumen roofing is applied. When
adequately attached to walls, supports and other roofing layers, plywood and OSB contribute to one of the most solid
and stable roof systems available.
Plywood and OSB are light and easy to work with, making the construction process easier and more time efficient. The
lightness in weight does not compromise the panels’ strength; on the contrary, one of the greatest benefits of plywood
and OSB is their diaphragm shear strength. In addition, panels are less expensive than other options, allowing builders
to pass cost savings on to the owners.
UL Roof Assemblies
Two UL-Rated plywood roof systems with hot-mopped built-up roofing over a mechanically fastened roofing base sheet
are qualified for fully-wind-resistive ratings (Class 90).
One of these systems, UL Construction No. NM519, is illustrated in Figure 1. It uses 15/32-inch APA RATED
SHEATHING Exposure 1 marked PS 1 (C-D Exposure 1 plywood), installed across nominal 2-inch wood joists spaced
a maximum of 24 inches o.c. For a fully-wind-resistive rating (Class 90), the three-ply built-up roofing consists of a
fiberglass mat base sheet (UL Type G2) that is mechanically fastened to the plywood roof deck at lapped edges and
along three intermediate rows with a staple/tape system and two plies of fiberglass mat ply sheets (UL Type G1) that are
hot-mopped to the base sheet.
The second, illustrated in Figure 2, is UL Construction No. NM520, a panelized roof deck of 15/32-inch APA RATED
SHEATHING Exposure 1 marked PS 1 (C-D Exposure 1 plywood). The ­panels are installed parallel to 2x4 joists spaced
a maximum of 24 inches o.c., framed into glulam beams. For a fully-wind-resistive (Class 90) rating, the three-ply
built-up roofing is installed as described above for NM519 construction, with the rayon tape spaced a maximum of 81/2 inches o.c. If the roofing base sheet is fastened to the plywood roof deck at lapped edges and along two intermediate
rows with a staple/tape system
spaced a maximum of 11-1/3
FIGURE 1
inches o.c., the roofing sysFULLY-WIND-RESISTIVE ROOF ASSEMBLY — UL CLASS 90 (NM519)
tem qualifies for a semi-wind1/4"-wide rayon tape
Two-ply sheets (UL Type G1asphalt glass fiber mat,
resistive rating (Class 60).
Panelized roofs are commonly
used on the West Coast for
seismic or wind resistance
and are becoming increasingly
popular in Texas and Gulf
Coast regions where windrated roofing systems can be
used with the diaphragm shear
strength of wood roof decks
to provide economical, windresistant structures. Panelized
roof systems are also fast and
economical to assemble and
install. Because the panelized
sections are assembled on the
(rows spaced at
8-1/2" o.c. typ.)
10 lb nominal) hot-mopped with
surface flood coat(b)
2" nominal Douglas-fir or
southern pine framing
spaced 24" o.c.
maximum(a)
16-ga. x 7/8"-long
coated staples
spaced 4" o.c. typ.
15/32" APA RATED
SHEATHING 32/16 Exposure 1
plywood marked PS 1
Plywood face grain direction
Base sheet (UL Type G2 asphalt
glass fiber mat, 20 lb nominal)(b)
8d common deformed shank nails
(0.131" x 2-1/2"), spaced 6" o.c. at panel
ends and12" o.c. at interior supports
(a) Design in accordance with local building code requirements for roof loads and anchorage.
All framing must have 2" nominal or greater width for plywood deck nailing.
(b) Install roofing base and ply sheets with roll direction parallel to plywood face grain direction,
as with a panelized roof system.
Form No. G310
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© 2006 APA – The Engineered Wood Association
FIGURE 2
FULLY-WIND-RESISTIVE ROOF ASSEMBLY — UL CLASS 90 (NM520)
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www.apawood.org
All framing must have 2" nominal or greater width for plywood deck nailing.
(b) Install roofing base and ply sheets with roll direction parallel to plywood face grain direction,
as with a panelized roof system.
Wind-Rated Roofs
ground and lifted into the
place with a forklift, worker
time on the roof deck is minimized, increasing worker
safety on the job site.
Another type of wind-rated
roof construction uses proprietary metal roofing panels,
available from several sources,
installed over plywood roof
sheathing as shown in Figure
3. These constructions use
APA RATED SHEATHING
Exposure 1 marked PS 1
(C-D Exposure 1 plywood),
installed across wood or steel
framing spaced up to 24
inches o.c. Plywood thickness
depends on details of the proprietary construction, with a
minimum of 15/32 inch (Span
Rating 32/16) for some constructions, and 5/8 or 3/4 inch
(Span Rating 40/20 or 48/24,
respectively) for others. Metal
roofing panels are fastened to
the plywood roof sheathing or
framing with special clips and
screws.
Other types of proprietary
roofing products, such as prepared roof covering or steel
tile or shake panels, also are
rated for wind uplift resistance
when installed over 15/32inch plywood roof sheathing.
Other constructions use a single-ply roofing membrane over
minimum 7/16-inch OSB panels as roofing substrate over
steel roof decking, or 15/32inch plywood roof sheathing. For details, consult the
UL Building Materials Directory
under Product Categories
TGIK and TGKX.
FIGURE 2
FULLY-WIND-RESISTIVE ROOF ASSEMBLY — UL CLASS 90 (NM520)
FIGURE sheets
2
Two-ply
(UL Type G1asphalt glass
1/4"-wide rayon tape (rows spaced
fiber
mat,10 lb nominal) hot-mopped
with — UL CLASS 90
at (NM520)
8-1/2" o.c.,(b) with 16-ga.
FULLY-WIND-RESISTIVE
ROOF ASSEMBLY
surface flood coat(c)
(0.0625" dia.) x 7/8"-long
coated staples
Two-ply sheets (UL Type G1asphalt glass
1/4"-wide rayon tapespaced
(rows spaced
4" o.c.)
Roof
purlins
or
trusses
(b)
fiber mat,10 lb
at 8-1/2" o.c., with 16-ga.
(a)nominal) hot-mopped with
spaced
8'
o.c.
surface flood coat(c)
(0.0625" dia.) x 7/8"-long
coated staples
Base sheet
spaced 4" o.c.)
(UL Type G2
asphalt
glass fiber mat,
Base sheet
(c)
short 20 lb nominal)
(UL Type G2
asphalt
10d (0.148" x 2-1/8")
common
glass fiber
mat,
nails,
4" o.c.
at nominal)
edges and
(c)
short
20 lb
6" o.c. at interior supports(b)
Roof purlins
Steel
joist or trusses
spaced 8' o.c.(a)
hangers
Steel joist
hangers
15/32"
APA RATED
SHEATHING
32/16 Exposure 1 plywood
15/32" PS 1 (4 plies minimum,
marked
10d (0.148"
x 2-1/8")
2" nominal
Douglas-fir
or common
southern
APAGroup
RATED1 species) or 15/32"
all
nails,
4" o.c.
at edges
pine
framing
spaced
24" and
o.c.
SHEATHING
APA STRUCTURAL I RATED
6" o.c. at interior supports(b)
32/16 Exposure
1 plywood
SHEATHING
32/16
plywood marked PS 1
Plywood face grain direction
marked PS 1 (4 plies minimum,
2" nominal Douglas-fir or southern
all Trusses
Groupor1I-joists
species)
orfor
15/32"
(a)
used
purlins must have chords or flanges of 1-3/4"
minimumspaced
depth for
pine framing
24" o.c.
APA
STRUCTURAL
I RATED
plywood
deck nailing.
SHEATHING 32/16 plywood marked PS 1
Plywood face grain direction
(b) For semi-wind-resistive assemblies (Class 60), plywood deck nailing spaced 6" o.c. at all supports
and roofing base sheet attached with rayon tape rows spaced 11-1/3" o.c.
(a) Trusses or I-joists used for purlins must have chords or flanges of 1-3/4" minimum depth for
plywood
deck base
nailing.
(c) Install
roofing
and ply sheets with roll direction parallel to plywood face grain direction, as
with a panelized roof system.
(b) For semi-wind-resistive assemblies (Class 60), plywood deck nailing spaced 6" o.c. at all supports
and roofing base sheet attached with rayon tape rows spaced 11-1/3" o.c.
(c) Install roofing base and ply sheets with roll direction parallel to plywood face grain direction, as
with a panelized roof system.
FIGURE 3
METAL ROOFING PANELS — UL CLASS 90(a)
No. 15 asphalt
felt vapor retarder –
FIGURE
3
one or two
layers (may
be optional)
METAL
ROOFING
PANELS
— UL CLASS 90(a)
Metal roofing panels fastened to
plywood or framing with
steel clips and screws
2x4 15
wood
framing
No.
asphalt
felt (joists
vapor bolted
retarder –
Metal roofing panels fastened to
to steel
purlins
spaced
one
or two
layers
(may be optional)
plywood or framing with
48–60" o.c., or top
steel clips and screws
chord of trusses),
2x4
wood
framing
(joists
bolted
2x6 wood
8d deformed
to steel purlins
spaced
framing,
or
shank nails
48–60"
o.c.,
or
top
steel framing
or No. 8 x 2"
chord
of
trusses),
(min. 22 gage)
screws @ 6" o.c. at
2x6 wood
8dor
deformed
edges and 6"
12" o.c.
framing, or
shank
at interior supports
(for nails
steel
steel framing
or
No.
8 x or
2"
framing, No. 6 x 1-1/4"
APA
SHEATHING
(min.RATED
22 gage)
screws
@
6"
o.c.
at
No. 12 x 1-5/8" screws)
plywood per PS 1
edges and 6" or 12" o.c.
(min. 15/32" for framing
at interior supports (for steel
spaced 16" o.c.; 19/32",
Caulk or tape to seal joints
framing, No. 6 x 1-1/4" or
APA RATED
5/8"
or 3/4"SHEATHING
for framing spaced 24" o.c.)
(check manufacturers’ recommendations)
No. 12 x 1-5/8" screws)
plywood per PS 1
(min.
15/32"
for
framing
(a) Some rated assemblies and constructions incorporate OSB sheathing and proprietary products.
spaced
o.c.; 19/32",
or tapeMaterials
to seal and
joints
When16"
designing
and specifying, check the Underwriters LaboratoriesCaulk
(UL) Roofing
5/8"
or 3/4"
for framing
spaced
(check
recommendations)
Systems
Directory
(Category
TGKX)24"
for o.c.)
complete details
on amanufacturers’
particular assembly
in UL
Construction Nos. 200-500 (series). A change in details may affect the wind uplift classification
of the rated
assembly.
(a) Some
assemblies and constructions incorporate OSB sheathing and proprietary products.
When designing and specifying, check the Underwriters Laboratories (UL) Roofing Materials and
Systems Directory (Category TGKX) for complete details on a particular assembly in UL
Construction Nos. 200-500 (series). A change in details may affect the wind uplift classification
of the assembly.
Form No. G310
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© 2006 APA – The Engineered Wood Association
■
www.apawood.org
Wind-Rated Roofs
FM Approvals -Tested Roof Assemblies
FM Approvals (FM) tested the decking and the finish systems together and assigned uplift classification ratings for
the wood roof decking and base sheet/insulation/cover board/cap-sheet combinations separately. The wood panel
decking system and the finish roofing system above the wood decks were assigned different Class 1 wind uplift
ratings based on that assessment. The test results were used to assign each wood structural panel system a classification that specified minimum panel thickness, maximum support spacing, minimum nail size and maximum
nail spacing. Figures 4–10 of this publication show wood decking systems meeting FM classes ranging from 1-60
to 1-135.
Any of the wood panel systems will work with any of the finish roofing combinations shown in Figures 11–15. The
overall uplift classification of the decking system plus finish roofing system will be the lower of the two system ratings.
Thus, a wood deck meeting Class 1-105 with an insulation/cover board combination meeting Class 1-90 would be rated
1-90, or a wood deck meeting Class 1-105 on an insulation/cover board combination meeting Class 1-120 would be
rated 1-105.
FIGURE 4
FM CLASS 1-60 WITH ARMA ROOF COVERING(c)
Decks
The type of framing supports used is the designer’s choice.
The figures in this publication depict different framing
options with each figure to show the range of choices
available. The spacing of the framing in relation to the
wood deck is important, however, and spacing must be
followed as dictated in the figures to meet the FM classes
listed. Framing supports must also be designed in accordance with local building code requirements for roof
loads and anchorage. All framing must be minimum net
thickness of 1-1/2 inches No. 2 Douglas-fir or southern
pine or equivalent. For wood I-joists, follow manufac­
turer’s recommendations for minimum nail spacing.
Two panel edge
clips per span,
evenly spaced
Deformed-shank nails
(0.135" x 2-1/8") spaced
4" o.c. at supported
panel ends and edges
and 8" o.c. at
interior supports
Deform
(0.135
6" o.c.
and ed
12" o.
interio
suppo
"
48
Min. APA
23/32" 5-ply
plywood or OSB 48/24
RATED SHEATHING
Figure 4 shows a wood deck that meets FM Class 1-60.
It uses a minimum of APA 23/32-inch 5-ply plywood or
OSB 48/24 RATED SHEATHING installed over framing
spaced at a maximum of 48 inches o.c. The sheathing
should be secured to supports using deformed-shank nails
(minimum 0.135 x 2-1/8 inches) spaced a maximum of
4 inches o.c. along supported ends and edges and
8 inches o.c. along interior supports. Unsupported panel
edges should be clipped using two metal panel clips
evenly spaced between supports.
Minimum
1-1/2" net thickness
No. 2 Douglas-fir or
southern pine framing, or
equivalent, spaced
48" o.c. maximum(a)(b)(d)
(a) Design in accordance with local building code requirements for
roof loads and anchorage. All framing must be minimum net
thickness of 1-1/2 inches No. 2 Douglas-fir or southern pine or
equivalent. For wood I-joists, follow manufacturer’s
recommendations for minimum nail spacing.
(b) Attach wood framing to min. 22 ga., 1-1/2" deep wide-rib steel
roof deck with screws at 6" o.c.
(c) Panel strength axis across supports for direct-to-support
spacing as shown. To install panels with strength axis parallel to
supports spaced 24" o.c., as in panelized roof systems, see
minimum panel requirements listed in Table 2.
(d) Wood glulams, I-joists or trusses can be used in place of the
bar joists illustrated. The steel decking can be used over the
wood members.
Figure 5 depicts a wood deck meeting FM Class 1-75, with a minimum 15/32-inch 5-ply APA plywood or OSB 32/16
RATED SHEATHING. Sheathing should be installed over minimum 2x framing spaced at a maximum of 32 inches o.c.
using deformed-shank nails (minimum 0.135 x 2-1/8 inches) spaced a maximum of 6 inches o.c. along panel edges
and 12 inches o.c. over interior supports.
Form No. G310
FIGUR
FM CL
■
© 2006 APA – The Engineered Wood Association
■
www.apawood.org
Min. A
15/32
plywoo
32/16
(a) Desi
roof
thick
equi
reco
(b) Pane
spac
supp
min
c)
edge
span,
paced
nimum
kness
s-fir or
ng, or
paced
a)(b)(d)
ents for
m net
pine or
ib steel
rallel to
ee
the
the
Wind-Rated Roofs
FIGURE 5
FIGURE 5
(b)
(b)
FM CLASS
WITH
FM1-75
CLASS
1-75ARMA
WITHROOF
ARMACOVERING
ROOF COVERING
FIGURE 6
FIGURE 6
(b)
(b)
FM CLASS
WITH
FM1-90
CLASS
1-90ARMA
WITHROOF
ARMACOVERING
ROOF COVERING
Deformed-shank
nails
Deformed-shank
nails
(0.135" x(0.135"
2-1/8")x spaced
2-1/8") spaced
6" o.c. at6"panel
ends
o.c. at
panel ends
and edges
and
and
edges and
12" o.c. at
12" o.c. at
interior interior
supportssupports
Deformed-shank
nails
Deformed-shank
nails
(0.135" x(0.135"
2-1/8")x spaced
2-1/8") spaced
4" o.c. at4"panel
ends
o.c. at
panel ends
and edges
and
8" o.c.
and
edges
and 8" o.c.
at interior
at interior
supportssupports
All panelAll panel
edges edges
supported
supported
"
32
"
Min. APAMin.
19/32"
APA 19/32"
4-ply plywood
or
4-ply plywood
or
OSB 40/20
OSBRATED
40/20 RATED
SHEATHING
SHEATHING
MinimumMinimum
1-1/2" net
1-1/2" net
thicknessthickness
No. 2 No. 2
Min. APAMin. APA
Douglas-fir
or southern
Douglas-fir
or southern
15/32" 5-ply
15/32" 5-ply
pine framing,
or equivalent,
pine framing,
or equivalent,
plywoodplywood
or OSB or OSB
(a)
(a)
spaced 32"
o.c. maximum
32/16 RATED
spaced
32" o.c. maximum
32/16SHEATHING
RATED SHEATHING
(a) Design(a)
in Design
accordance
with local with
building
requirements
for
in accordance
localcode
building
code requirements
for
roof loadsroof
andloads
anchorage.
All framing
be minimum
net
and anchorage.
Allmust
framing
must be minimum
net
thickness of
1-1/2 inches
No.inches
2 Douglas-fir
or southern
or pine or
thickness
of 1-1/2
No. 2 Douglas-fir
or pine
southern
equivalent.
For wood For
I-joists,
follow
manufacturer’s
equivalent.
wood
I-joists,
follow manufacturer’s
recommendations
for minimum
nail spacing.
recommendations
for minimum
nail spacing.
(b) Panel strength
acrossaxis
supports
direct-to-support
(b) Panelaxis
strength
across for
supports
for direct-to-support
spacing asspacing
shown.as
Toshown.
install panels
with
strength
parallel
To install
panels
withaxis
strength
axistoparallel to
supports spaced
24"
o.c., as
panelized
roof systems,
supports
spaced
24"ino.c.,
as in panelized
roofsee
systems, see
minimum minimum
panel requirements
listed in Table
panel requirements
listed2.in Table 2.
(a) Design(a)
in Design
accordance
with local with
building
requirements
for
in accordance
localcode
building
code requirements
for
roof loadsroof
andloads
anchorage.
All framing
be minimum
net
and anchorage.
Allmust
framing
must be minimum
net
thickness of
1-1/2 inches
No.inches
2 Douglas-fir
or southern
or pine or
thickness
of 1-1/2
No. 2 Douglas-fir
or pine
southern
equivalent.
For wood For
I-joists,
follow
manufacturer’s
equivalent.
wood
I-joists,
follow manufacturer’s
recommendations
for minimum
nail spacing.
recommendations
for minimum
nail spacing.
(b) Panel strength
acrossaxis
supports
direct-to-support
(b) Panelaxis
strength
across for
supports
for direct-to-support
spacing asspacing
shown.as
Toshown.
install panels
with
strength
parallel
To install
panels
withaxis
strength
axistoparallel to
supports spaced
24"
o.c., as
panelized
roof systems,
supports
spaced
24"ino.c.,
as in panelized
roofsee
systems, see
minimum minimum
panel requirements
listed in Table
panel requirements
listed2.in Table 2.
FM Class 1-105 can be achieved by using the deck illustrated in Figure 7. A minimum of 19/32-inch 4-ply APA
plywood or OSB 40/20 RATED SHEATHING over framing spaced a maximum of 32 inches o.c. The sheathing is attached to supports using deformed-shank nails
(minimum 0.135 x 2-1/8 inches) spaced a maximum
of 4 inches o.c. along supported panel edges and at
a maximum of 6 inches o.c. along interior supports.
Unsupported panel edges are clipped using one metal
panel edge clip centered between the supports.
Figure 8 shows a wood deck meeting FM Class 1-120
using a minimum of 19/32-inch 4-ply plywood or OSB
40/20 APA RATED SHEATHING secured to supports
using deformed-shank nails (minimum 0.135 x 2-1/8
Form No. G310
"
24 Minimum
Minimum
1-1/2" net
1-1/2" net
thicknessthickness
No. 2 No. 2
Douglas-fir
or southern
Douglas-fir
or southern
pine framing,
or equivalent,
pine framing,
or equivalent,
(a)
(a)
spaced 24"
o.c. maximum
spaced
24" o.c. maximum
24
"
32
The wood deck in Figure 6 meets FM Class 1-90 by using
a minimum of 19/32-inch APA 4-ply plywood or OSB
40/20 RATED SHEATHING secured to supports using
deformed-shank nails (minimum 0.135 x 2-1/8 inches)
spaced a maximum of 4 inches o.c. along the perimeter
ends and edges and at 8 inches o.c. along interior supports. The panels are supported on framing spaced a
maximum of 24 inches o.c.
All panelAll panel
edges edges
supported
supported
FIGURE 7
FM CLASS 1-105 WITH ARMA ROOF COVERING(b)
Deformed-shank nails
(0.135" x 2-1/8") spaced
4" o.c. at panel ends
and edges and 6" o.c. at
interior supports
FIGURE
FM CLA
One panel edge
clip per span,
centered
Deform
(0.135
4" o.c.
and ed
at inter
suppor
Supports(a)
Min. AP
19/32"
plywoo
RATED
"
32
Min. APA
19/32" 4-ply
plywood or OSB 40/20
RATED SHEATHING
(a) Design in accordance with local building code requirements for
roof loads and anchorage. All framing must be minimum net
thickness of 1-1/2 inches No. 2 Douglas-fir or southern pine or
equivalent. For wood I-joists, follow manufacturer’s
recommendations for minimum nail spacing.
(b) Panel strength axis across supports for direct-to-support
spacing as shown. To install panels with strength axis parallel to
supports spaced 24" o.c., as in panelized roof systems, see
minimum panel requirements listed in Table 2.
■
© 2006 APA – The Engineered Wood Association
■
www.apawood.org
(a) Desig
roof
thick
equiv
recom
(b) Pane
spac
supp
minim
(b)
edge
span,
ntered
orts(a)
nts for
m net
pine or
allel to
ee
Wind-Rated Roofs
FIGURE 8FIGURE 8
(b)
(b)
FM CLASS
FM1-120
CLASS
WITH
1-120
ARMA
WITH
ROOF
ARMA
COVERING
ROOF COVERING
FIGURE 9FIGURE 9
(b)
(b)
FM CLASS
FM1-135
CLASS
WITH
1-135
ARMA
WITH
ROOF
ARMA
COVERING
ROOF COVERING
Deformed-shank
Deformed-shank
nails
nails
(0.135" x (0.135"
2-1/8") xspaced
2-1/8") spaced
4" o.c. at 4"
panel
o.c. ends
at panel ends
and edgesand
andedges
6" o.c.
and 6" o.c.
at interiorat interior
supports supports
Deformed-shank
Deformed-shank
nails
nails
(0.135" x (0.135"
2-1/8") xspaced
2-1/8") spaced
4" o.c. at 4"
panel
o.c. ends
at panel ends
and edgesand
andedges
6" o.c.
and
at 6" o.c. at
interior supports
interior supports
All panel All panel
edges
edges
supportedsupported
All panel All panel
edges
edges
supportedsupported
"
24
"
32
"
32
MinimumMinimum
1-1/2" net1-1/2" net
thickness thickness
No. 2
No. 2
Min. APA Min.
19/32"
APA 19/32"
Douglas-fir
Douglas-fir
or southern
or southern
4-ply plywood
4-ply or
plywood
OSB or OSB
pine framing,
pine or
framing,
equivalent,
or equivalent,
40/20 RATED
40/20 RATED
(a)
(a)
spaced 24"
spaced
o.c. maximum
24" o.c. maximum
SHEATHING
SHEATHING
MinimumMinimum
1-1/2" net1-1/2" net
thickness thickness
No. 2
No. 2
Min. APA Min. APA
Douglas-fir
Douglas-fir
or southern
or southern
19/32" 4-ply
19/32" 4-ply
pine framing,
pine or
framing,
equivalent,
or equivalent,
plywood or
plywood
OSB 40/20
or OSB 40/20
(a)
(a)
spaced
o.c. maximum
32" o.c. maximum
RATED SHEATHING
RATED SHEATHING spaced 32"
(a) Design (a)
in accordance
Design in accordance
with local building
with local
code
building
requirements
code requirements
for
for
roof loads roof
and anchorage.
loads and anchorage.
All framingAll
must
framing
be minimum
must be net
minimum net
thickness ofthickness
1-1/2 inches
of 1-1/2
No.inches
2 Douglas-fir
No. 2 Douglas-fir
or southernorpine
southern
or
pine or
equivalent.equivalent.
For wood I-joists,
For wood
follow
I-joists,
manufacturer’s
follow manufacturer’s
recommendations
recommendations
for minimum
for nail
minimum
spacing.
nail spacing.
(b) Panel strength
(b) Panel
axis
strength
acrossaxis
supports
acrossfor
supports
direct-to-support
for direct-to-support
spacing as spacing
shown. To
as install
shown.panels
To install
withpanels
strength
with
axis
strength
parallel
axis
to parallel to
supports spaced
supports
24"spaced
o.c., as24"
in panelized
o.c., as in roof
panelized
systems,
roof
see
systems, see
minimum panel
minimum
requirements
panel requirements
listed in Table
listed
2. in Table 2.
(a) Design (a)
in accordance
Design in accordance
with local building
with local
code
building
requirements
code requirements
for
for
roof loads roof
and anchorage.
loads and anchorage.
All framingAll
must
framing
be minimum
must be net
minimum net
thickness ofthickness
1-1/2 inches
of 1-1/2
No.inches
2 Douglas-fir
No. 2 Douglas-fir
or southernorpine
southern
or
pine or
equivalent.equivalent.
For wood I-joists,
For wood
follow
I-joists,
manufacturer’s
follow manufacturer’s
recommendations
recommendations
for minimum
for nail
minimum
spacing.
nail spacing.
(b) Panel strength
(b) Panel
axis
strength
acrossaxis
supports
acrossfor
supports
direct-to-support
for direct-to-support
spacing as spacing
shown. To
as install
shown.panels
To install
withpanels
strength
with
axis
strength
parallel
axis
to parallel to
supports spaced
supports
24"spaced
o.c., as24"
in panelized
o.c., as in roof
panelized
systems,
roof
see
systems, see
minimum panel
minimum
requirements
panel requirements
listed in Table
listed
2. in Table 2.
inches) spaced a maximum of
4 inches o.c. along panel edges and
6 inches o.c. along interior supports.
Framing should be spaced at a maximum of 32 inches o.c.
In Figure 9, the wood deck meets
FM Class 1-135. A minimum of
19/32-inch 4-ply plywood or OSB
40/20 APA RATED SHEATHING is
secured to supports using deformed
shank nails (minimum 0.135 x 21/8 inches) spaced a maximum of
4 inches o.c. along panel edges and
6 inches o.c. along interior supports. The sheathing is supported
on framing spaced at a maximum of
24 inches o.c.
Figure 10 illustrates a panelized roof
system that meets the panel attachment requirements for the various
FM Windstorm Classifications. See
Table 2 for the minimum panel
thickness and number of plies
"
24
FIGURE 10
FM CLASS 1-135 WITH ARMA ROOF COVERING(b)
Deformed-shank nails
(0.135" x 2-1/8") spaced
4" o.c. at panel ends
and edges and 6" o.c. at
interior supports
"
24
2x6
96
"
Supports(a)
Min. APA
19/32" 5-ply
plywood or OSB 40/20
RATED SHEATHING
(a) Design in accordance with local building code requirements for roof loads and anchorage.
All framing must be minimum net thickness of 1-1/2 inches No. 2 Douglas-fir or southern
pine or equivalent. For wood I-joists, follow manufacturer’s recommendations for minimum
nail spacing.
(b) To install panels with strength axis parallel to supports spaced 24" o.c., as illustrated, see
minimum panel requirements listed in Table 2.
Form No. G310
■
© 2006 APA – The Engineered Wood Association
■
www.apawood.org
10
Wind-Rated Roofs
required (for plywood) to meet the minimum strength and attachment requirements for each FM Windstorm
Classification using a typical panelized roof system installation with panel strength axis parallel to supports. The maximum support spacing is 24 inches o.c. for a typical panelized roof system.
The minimum panel thickness is based on the panels tested by FM or the minimum bending capacity required to resist
the design uplift pressures, whichever requirement is more restrictive. For instance, if the tested system were a 4-ply
plywood panel with the panel strength axis across supports, a panelized roof system with the panel strength axis parallel to supports may require a 5-ply panel because of its superior cross-panel strength. The design uplift pressures are
based on International Building Code Table 1609.6.2.1(2)
FIGURE 11
for components and cladding at corner locations and
FM CLASS 1-90
ASCE 7-05 (3-second gust).
Hot asphalt
Insulation/Cover Boards
The insulation/cover boards fill a layer of the roof system
between the wood deck and the roof covering. For all
the FM tested figures illustrated here, an Asphalt Roofing
Manufacturers Association (ARMA) roof covering1 must
be applied using hot asphalt. ARMA roof coverings can be
built up or modified bitumen. For more information on
roof coverings, consult the ARMA web site www.asphaltroofing.org.
Figure 11 illustrates an insulation/cover board combination that meets FM Class 1-90. A minimum thickness of
1-1/2 inches is required for the foam insulation, which
is attached to the wood deck using 3-inch stress plate
FIGURE 11
fasteners applied at a maximum tributary area of 1.45
FM CLASS 1-90
square feet per fastener (a maximum of 14 inches o.c.). A
3" plate
fasteners
Hot asphalt
minimum 1/2-inch fiberboardspaced
cover
board,
adhered with
14" o.c. max.
(1.45
sf/fasteners)
hot asphalt and walked in, covers the insulation.
ARMA roof
covering
12, which also meets FM Class 1-90, an ARMA
(builtInupFigure
or
modified
base sheet is secured to the wood deck with rayon tape
bitumen)
and staples. Strips of base sheet overlap for a minimum of
2 inches, and one strip of rayon tape is placed along the
center of the overlap. Additional tape is placed in three
evenly spaced rows between the laps. Staples
Foam(7/16-inch
insulation
crown x 7/8-inch 16 gage) are spaced
a
maximum of
(1-1/2" min.)
Min. 1/2"
5 inches o.c. along each row of rayon tape. Hot asphalt
fiberboard
coveradheres
board an ARMA ply sheet to
Wood
structural
panel
the base
sheet.
ARMA roof
covering
(built up or
modified
bitumen)
3" plate fasteners
spaced 14" o.c. max.
(1.45 sf/fasteners)
Min. 1/2"
fiberboard
cover board
ARMA r
(built up
bitumen
Foam
insulation
(1-1/2" min.)
Wood structural panel
Wood
structur
panel
FIGURE 12
FM CLASS 1-90
Rayon tape down center of each minimum 2-inch-wide
FIGURE
14 lap and 3 rows of rayon tape evenly spaced
base-sheet
between
laps.
Rayon tape with 7/16" crown x 7/8" 16 ga.
FM
CLASS
1-120
staples at 5" o.c.
ARMA
roof covering
Hot asphalt
(built up or modified
bitumen)
ARMA roof covering
(built up or modified
Hot
asphalt
bitumen)
3" plate fasteners
spaced 14" o.c. max.
(1.45 sf/fasteners)
Min. 1/2"
fiberboard
cover
board
ARMA roof covering
(built up or modified
bitumen)
■
FIGU
FM C
FIGURE
Hot a
FM CLA
ARMA
ARMA
(built
(builtu
bitume
bitum
Hot
asp
2" min
overla
Compo
foam n
(2" min
Min.
1/2"
2" min.
fiberboard
overlap
cover
board
3" plate fasteners
spaced 14" o.c. max.
(1.45 sf/fasteners)
Form No. G310
Rayon t
base-sh
between
staples
Hot asp
ARMA
base sheet
ARMA ply
or cap sheet
Wood structural panel
FIGURE
14 roof coverings consist of minimum 3-ply built-up roof or minimum 2-ply
FIGURE
15 bitumen roof coverings. The bottom sheet is mechani1 ARMA
modified
FM CLASS
1-120
FM
CLASS
1-135
cally fastened
or is adhered to the substrate with hot asphalt. Additional sheets are
adhered
with
hot asphalt.
Hot asphalt
FM CLA
2" min.
overlap
Wood
structural
panel
Foam
insulation
(12" max.)
ARMA roof covering
(built up or modified
bitumen)
FIGURE
3" plate fasteners
spaced 14" o.c. max.
(1.45 sf/fasteners)
Hot asphalt
© 2006 APA – The Engineered Wood Association
Composite or
foam nail base
(2" min.)
■
www.apawood.org
Wood
structu
panel
Option
foam in
(12" ma
foam n
11
Wind-Rated Roofs
FIGURE
An12ARMA
base sheet is also used in Figure 13, which
Class 1-105. In this case, the base sheet overminimum
ofeach
2 inches,
and
3-inch plate fasteners
Rayonlaps
tapeadown
center of
minimum
2-inch-wide
base-sheet lap and 3 rows of rayon tape evenly spaced
should
be spaced
a maximum
9 inches
between
laps. Rayon
tape with
7/16" crownof
x 7/8"
16 ga. o.c. at the
staples
at 5" o.c.
center
of the base sheet overlap. Evenly spaced between
Hot asphalt
the 11
laps are three rows of 3-inch plate fasteners spaced a
FIGURE
FIGURE 11
ARMA
roof
maximum
inches o.c. on each row.
FM CLASS
1-90of 9
FMcovering
CLASS
1-90
FIGURE 13
FM CLASS 1-105
FM CLASS
meets1-90
FM
(built up or modified
bitumen)
3" plate3"
fasteners
Hot Figure
asphalt
plate fasteners
Hot asphalt
14 provides an insulation/cover
board
combinaspaced spaced
14" o.c.14"
max.
o.c. max.
2" min.
(1.45
sf/fasteners)
tion
that
meets
FM
Class
1-120.
A
layer
of
foam
insula(1.45 sf/fasteners)
overlap
ARMA roof
ARMA roof
tion,
ranging between 2 and 12 inches thick, is adhered
covering
covering
(builttoupthe
or wood
(built
up or structural panels using 3-inch plate fasteners
modified
modified
bitumen)
applied
at a maximum contributory area of 1.45 square
bitumen)
feet per fastener (a maximum of 14 inches o.c.). The
ARMA fiberboard
insulation is covered with a minimum 1/2-inch
base sheet
cover
board,
adhered
with
hot
asphalt
and
walked in.
Wood
structural
panelThe
assembly in Figure 15 meets
Hot asphalt
3" plate fasteners at 9" o.c. max.
through center of min. 2" wide
base-sheet laps
FIGURE
12 covering
FIGURE
12
ARMA roof
ARMA base
FM
CLASS
1-90
(built
upFM
or CLASS
modified
1-90
sheet
bitumen)
Rayon tape
down
each of
minimum
2-inch-wide
Rayon
tapecenter
downofcenter
each minimum
2-inch-wide
2" min.
base-sheet
lap andlap
3 rows
rayonoftape
evenly
base-sheet
and of
3 rows
rayon
tapespaced
evenly spaced
overlap laps. Rayon tape with 7/16" crown x 7/8" 16 ga.
between
between laps. Rayon tape with 7/16" crown x 7/8" 16 ga.
staples at
5" o.c.
staples
at 5" o.c.
Hot asphalt
Hot asphalt
ARMA roof
covering
ARMA
roof covering
(built up(built
or modified
up or modified
bitumen)bitumen)
2" min. 2" min.
overlap overlap
Wood
structural
panel
ARMA
ply Foam
Foam
cap
sheet
insulation
insulation
FMorClass
1‑135.
In this
(1-1/2" (1-1/2"
min.) min.)
3 evenly
spaced
rows of 3"
plate fasteners at
9" o.c. between
base-sheet laps
FM CLASS
1-135 1-135
FM CLASS
ARMA roof
covering
ARMA
roof covering
(built up(built
or modified
up or modified
bitumen)bitumen)
3" plate3"
fasteners
plate fasteners
spaced spaced
14" o.c.14"
max.
o.c. max.
(1.45 sf/fasteners)
(1.45 sf/fasteners)
Hot asphalt
Hot asphalt
Hot asphalt
Hot asphalt
Min. 1/2"
Min. 1/2"
fiberboard
fiberboard
cover cover
board board
Composite
or
Composite
or
foam nail
base
foam
nail base
(2" min.)(2" min.)
Optional
foam insulation
(12" max., including
foam nail base)
Foam Foam
insulation
insulation
(12" max.)
(12" max.)
3" plate3"
fasteners
plate fasteners
spaced spaced
14" o.c.14"
max.
o.c. max.
(1.45 sf/fasteners)
(1.45 sf/fasteners)
Wood structural panel
Optional
Optional
foam insulation
foam insulation
(12" max.,
(12"including
max., including
foam nail
base)
foam
nail base)
Wood structural
panel panel
Wood structural
Wood structural
panel panel
Wood structural
For More Information
APA offers numerous publications on roof assemblies. For a complete list, visit www.apawood.org/publications and
search for “roof.”
You may also contact the APA Product Support Help Desk by calling (253) 620-7400 or e-mailing help@apawood.org.
Form No. G310
■
Hot a
ARMA
(built
bitum
Min. 1/2"
Min. 1/2"
assembly,
a foam insulation base layer directly above the
fiberboard
fiberboard
cover
board
Wood
structural
panel
cover
board is optional, but
wood
sheathing
a minimum
of a 2-inch
thickWood structural
panel composite or foam nail base is required. The maximum
ARMA
ARMA
base sheet
FIGURE 15
base
sheet
ness of the optional foam insulation and the foam nail base – Wood
the total
insulation
thickness
–
is
12
inches.
The
nail
Wood
FM CLASS 1-135
ARMA
ply
structural applied at a rate of 1.45 square
ARMA
base and optional insulation attach to the sheathing with 3-inchstructural
plate fasteners
feet
per ply
panel panel
or cap sheet
or cap sheet
ARMA
roof covering
fastener
(a maximum of 14 inches
o.c.).fasteners
3" plate
(built up or modified
spaced 14" o.c. max.
bitumen)
(1.45 sf/fasteners)
Hot
asphalt
FIGUREFIGURE
14
FIGUREFIGURE
15
14
15
FM CLASS
1-120 1-120
FMor
CLASS
Composite
foam nail base
ARMA
roof
covering
ARMA
roof covering
(2"
min.)
(built up(built
or modified
up or modified
bitumen)bitumen)
FIGU
FM C
© 2006 APA – The Engineered Wood Association
■
www.apawood.org
2" mi
overla
Wood
struct
panel
About APA
APA – The Engineered Wood Association is a nonprofit trade association of and for structural wood panel,
glulam timber, wood I-joist, laminated veneer lumber and other engineered wood product manufacturers. Based in Tacoma, Washington, APA represents approximately 150 mills throughout North America,
ranging from small, independently owned and operated companies to large integrated corporations.
Always insist on engineered wood products bearing the mark of quality – the APA or APA EWS trademark. Your APA engineered wood purchase is not only your highest possible assurance of product quality, but an investment in the many trade services that APA provides on your behalf. The Association’s
trademark appears only on products manufactured by member mills and is the manufacturer’s assurance
that the product conforms to the standard shown on the trademark.
For panels, that standard may be an APA performance standard, the Voluntary Product Standard
PS 1-95 for Construction and Industrial Plywood or Voluntary Product Standard PS 2-04, Performance
Standards for Wood-Based Structural-Use Panels. Panel quality of all APA trademarked products is
subject to verification through APA audit.
APA’s services go far beyond quality testing and inspection. Research and promotion programs play important roles in developing and improving plywood and other panel
construction systems, and in helping users and specifiers to better understand and apply engineered wood products. For more information on wood construction systems, contact
APA – The Engineered Wood Association, 7011 S. 19th St., Tacoma, Washington 98466, or visit the
Association’s web site at www.apawood.org.
We have field representatives in many major U.S. cities and in Canada
who can help answer questions involving APA trademarked products.
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Disclaimer
The information contained herein is based on APA – The Engineered Wood Association’s continuing programs of laboratory testing, product research, and comprehensive field experience. Neither
APA, nor its members make any warranty, expressed or implied, or assume any legal liability or
responsibility for the use, application of, and/or reference to opinions, findings, conclusions, or
recommendations included in this publication. Consult your local jurisdiction or design professional
to assure compliance with code, construction, and performance requirements. Because APA has no
control over quality of workmanship or the conditions under which engineered wood products are
used, it cannot accept responsibility for product performance or designs as actually constructed.
From No. G310/Issued June 2006