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Presented on [ Date ] by [ Presenter’s Name ]
Progressive Multi-Family Design: New Opportunities for Light Frame Mid-rise Structures
Workshop
“The Wood Products Council” is a
Registered Provider with The
American Institute of Architects
Continuing Education Systems
(AIA/CES), Provider #G516.
Credit(s) earned on completion of this
course will be reported to AIA CES for
AIA members. Certificates of
Completion for both AIA members
and non-AIA members are available
upon request.
This course is registered with AIA CES
for continuing professional education.
As such, it does not include content
that may be deemed or construed to
be an approval or endorsement by
the AIA of any material of
construction or any method or
manner of handling, using,
distributing, or dealing in any
material or product.
______________________________
Questions related to specific materials, methods,
and services will be addressed at the conclusion of
this presentation.
Updates to the California Building Code along with the availability of innovative new
products have created opportunities for designers to add value to their mixed-use and
multi-family projects by increasing scale and improving aesthetics. This workshop will
introduce a new code allowance for additional stories in podium structures and review
specific ways it can impact building designs. Referencing built projects and common design
techniques, discussion will cover fire-rated detailing provisions, including those relevant to
the detailing of wood shaft walls, and options for cost-effectively integrating mass timber
into projects that are otherwise light wood-frame. Code provisions related to safety during
construction will also be reviewed to demonstrate how to minimize the risk of fire on large
wood projects.
Workshop Description
1. Determine the design Challenges and solutions using a multi-story podium under
four and five stories of wood-frame construction, using references to built examples
2. Discuss opportunities and requirements for wood shaft wall designs, including
detailing options, cost benefits and relevant code provisions.
3. Investigate opportunities for combining wood-frame and mass timber solutions in
multi-family mid-rise applications in order to take advantage of the aesthetics and
speed of mass timber while deriving the economic benefits of wood-frame
4.Review 2015 IBC Chapter 33 provisions regarding construction safety that can
minimize on-site risk of construction fires on large wood projects.
Learning Objectives
Presented on [ Date ] by [ Presenter’s Name ]
Examining Mid-rise Fire Resistance Rated Design for Shaft Enclosures, Beams and ColumnsImportant Provisions and Detailing Options
Presented by:
Lisa Podesto, PE, MS
Senior Technical Director
Outline
• Shaft Enclosure
• Code Provision Review
• Assembly Options
• Applications
• Individual Encasement
• Columns
• beams
Material Allowance Provisions
SECTION 713
SHAFT ENCLOSURES
713.2 Construction.
Shaft enclosures shall be constructed as fire barriers in accordance with 707 or
horizontal assemblies in accordance with section 711, or both.
SECION 707
FIRE BARRIERS
707.2 Materials.
Fire barriers shall be of materials permitted by the building type of construction.
There is no restriction on combustible material within shaft walls or fire barriers (when not also exterior
walls) in Types III, IV or V construction.
SECION 707
FIRE BARRIERS
707.5 Continuity.
Fire barriers shall extend from the top of he foundation or floor/ceiling assembly below to
the underside of the floor or roof sheathing, slab or deck above and shall be securely
attached thereto. Such fire barriers shall be continuous though concealed space such as the
space above a suspended ceiling. Joints and voids at intersections shall comply with Sections
707.8 and 707.9.
Continuity Provisions
SECTION 713
SHAFT ENCLOSURES
713.5 Continuity.
Shaft enclosures shall be constructed as fire barriers in accordance with 707 or horizontal
assemblies in accordance with section 711, or both and shall have continuity in accordance
with 707.5 for fire barriers or Section 711.2 for horizontal assemblies, as applicable.
Continuity Provisions
Floor or roof deck
Fire-resistance-
rated floor /
ceiling
assembly
Nonfire-resistance-
rated floor/ceiling
assembly
Fire-resistance-rated
floor/ceiling assembly
Fire-resistance-
rated floor/ceiling
assembly or
roof/ceiling
assembly
IBC Commentary Figure 707.5 – Continuity of Fire BarriersFIGURE 1:
Shaft Wall Requirements:
• Must extend from top
of the foundation or
floor/ceiling assembly
below to the underside
of the floor or roof
sheathing
• Through concealed
spaces
Fire barriers, including shaft walls, must extend from top of sheathing to underside of sheathing. Sheathing
does not obstruct continuity.
SECION 707
FIRE BARRIERS
707.5 Continuity.
Fire barriers shall extend from the top of he foundation or floor/ceiling assembly below to
the underside of the floor or roof sheathing, slab or deck above and shall be securely
attached thereto. Such fire barriers shall be continuous though concealed space such as the
space above a suspended ceiling. Joints and voids at intersections shall comply with Sections
707.8 and 707.9.
Continuity Provisions
SECION 707.8
FIRE BARRIERS
707.8 Joints.
Joints made in or between fire barriers, and joints made at the intersection of fire barriers
with underside of a fire resistance-rated floor or roof sheathing, slab or deck above, and the
exterior vertical wall intersection shall comply with Section 715.
Joint vs. Assembly Intersection
SECTION 202
DEFINITIONS
Joint. The opening in or between
adjacent assemblies that is created
due to building tolerances, or is
designed to allow independent
movement of the building in any plane
caused by thermal, seismic, wind or
any other loading.
Assembly intersections that are in direct contact and securely attached are not considered joints.
Penetrations Provisions
SECTION 713
SHAFT ENCLOSURES
713.8 Penetrations.
Penetrations in shaft enclosure shall be protected in accordance with Section 714 as
required for fore barriers. Structural elements such as beams or joists, where protected in
accordance with Section 714 shall be permitted to penetrate a shaft enclosure.
713.8.1 Prohibited penetrations.
Penetrations other than those necessary for the purpose of the shaft shall not be permitted
in shaft enclosures.
SECION 707
FIRE BARRIERS
707.7 Penetrations.
Penetrations of fire barriers shall comply with Section 714.
707.7.1 Prohibited penetrations.
Penetrations into enclosures for exit access stairways and ramps, interior exit stairways
and ramps, and exit passageways shall be allowed only where permitted by Sections 1019,
1023.5, 1024.6 respectively.
Penetrations Provisions
SECTION 714
PENETRATIONS
714.3.1.1 Fire-resistance-rated assemblies.
Penetrations shall be installed as tested in an approved fire resistance rated assembly.
OR
714.3.1.2 Through-penetration firestop system.
Through penetrations shall be protected by an approved penetration firestop system
installed as tested in accordance with ASTM E814 or UL 1479, with a minimum positive
pressure differential of .01 inch of water and shall have an F rating of not less than the
required fire-resistance rating of the wall penetrated.
Penetration Provisions
Penetration Provisions
• Most penetration firestopping is approved using 714.3.1.2
• Many approved firestopping sealants for use with wood and tested for proper fire-resistance rating
Structural members are specifically called out as allowable penetrants in shaft enclosures.
SECION 707
FIRE BARRIERS
707.5.1 Supporting Construction.
The supporting construction for a fire barrier shall be protected to afford the required fire-
resistance rating of the fire barrier supported. Hollow vertical spaces within a fire barrier
shall be fireblocked in accordance with Section 718.2 at every floor level.
Supporting Construction Provisions
SECTION 713
SHAFT ENCLOSURES
713.5 Continuity.
Shaft enclosures shall be constructed as fire barriers in accordance with 707 or horizontal
assemblies in accordance with section 711, or both and shall have continuity in accordance
with 707.5 for fire barriers or Section 711.2 for horizontal assemblies, as applicable.
Supporting Construction:
• The supporting construction for a
fire barrier shall be protected to
afford the required fire-resistance
rating of the fire barrier
supported.
No less than
rating of wall above
Fire-rated wall
Fire-rated wall
Supporting Construction Provisions
Supporting Construction:
• The supporting construction for a
fire barrier shall be protected to
afford the required fire-resistance
rating of the fire barrier
supported.
No less than
rating of wall above
Fire-rated wall
Fire-rated wall
Supporting Construction Provisions
Section 202
DEFINITIONS
FIRE RESISTANCE RATING. The period of
time a building element, component or
assembly maintains the ability to
confine a fire, continues to perform a
giving structural function, or both as
determined by the tests of the methods
based on tests prescribed in Section 703
FIRE BARRIER. A fire resistance-rated
wall assembly of materials designed to
restrict the spread of fire in which
continuity is maintained
Fire Resistance Rating Requirement
Structural Performance
Fire Confinement
The intent of a fire barrier is to provide fire confinement. If a fire barrier wall is supported directly
by a wall below, the intersecting floor should not be considered a supporting element.
Detailing for Continuity
Platform Framing Semi-balloon Framing
Floor sheathing
Ledger for ceiling
attachment
Floor joist
Joist hanger
Floor beam
Floor-to-Shaft Wall Intersection Detail with
Supporting Beam Just Inboard of Wall
FIGURE
12:
Detailing for Continuity
Floor
sheathing
Top flange joist
hanger approved to
span 2 layers GWB
2 1/4”
2 ”W
H
Floor-to-Shaft Wall Intersection Detail with
Hangers Designed to Span Over Gypsum
FIGURE
13:
Floor sheathing
Joist hanger
Floor Framing Ledger Attached to
Shaft Wall through Two Layers of Gypsum
FIGURE
14:
Detailing for Continuity
Provisions
(2) 2x flat blocking between trusses
Extend wall gypsum to underside of
sheathing between trusses
Floor sheathing
Specify truss web holdback to
allow gypsum installation
Floor-to-Shaft Wall Intersection Detail with Gypsum
Extending to Underside of Sheathing between TrussesFIGURE
11:
Detailing for Continuity
• Assumes use of an approved fire rated assembly
• Fire-resistance rating continues to the underside of the deck
• Joists are an allowable penetrant to the tested assembly
• Use rated fire caulk around joist
• Fire-resistance rating still continues to the underside of the deck
• Assumes a tested assembly to the top of wall plate
• Above wall top plate, uses 703.3 allowance for fire-resistance calculations per 722
• 722 allows NDS Chapter 16 methods for fire resistance calculations for exposed wood
• The combustibility of the material is not an issue; must meet the fire rating requirement
Floor sheathing
Rim joist
Blocking
between
floor joists
Floor-to-Shaft Wall Intersection Detail with Blocking
Between Floor Joists
FIGURE
10:
Floor joist options:
•Solid sawn
•Trusses
•I-joists
Detailing for Continuity
Outline
• Shaft Enclosures
• Code Provision Review
• Assemblies
• Applications
• Individual Encasement
• Columns
• Beams
Shaft Wall Assemblies
Shaft Enclosure Fire Requirements:
(713.4 Fire-Resistance Rating)
• 2 hours (4 stories or more)
• 1 hour (less than 4 stories)
• Number of connected stories includes
basement but not mezzanine
• Fire rating shall not be less than floor
assembly penetrated, but need not
exceed 2 hours
Additional Considerations:
• Acoustic separation
• Space constraints
• Constructability
• Load capacity
• Load path
Shaft Wall Assemblies – Single Wall
1-Hour Rated Assemblies (Single Wall)
• UL 305 (Example Above)
• GA WP 3510
• UL U311
• UL U332
• IBC Table 721.1(2) Item 14-1.3
Shaft Wall Assemblies – Single Wall
2-Hour Rated Assemblies (Single wall)
• UL U301
• UL U334 (Example above)
• IBC Table 721.1(2) Item 14-1.5
• IBC Table 721.1(2) Item 15-1.16
Shaft Wall Assemblies – Double Wall
2-Hour Rated Assemblies (Double wall)
• UL U342
• UL U370
• GA WP3820
Shaft Wall Assemblies - Shaftliner
2-Hour Rated Assemblies (H-Stud)
• UL U336 (example above)
• UL U373
• UL U375
Single Wall Option
Source: UL U375
Double Wall Option
Shaft Wall Assemblies - Shaftliner
Shaft Wall Assemblies - Shaftliner
Shaftliner Wall Assembly with Wood Wall Each SideFIGURE 6:
Credit: ClarkDietrich
Shaft Walls Assemblies - Shaftliner
2 hour Assemblies (CH Stud)
• UL U415 (example above)
• UL V455
• UL V433
• GA ASW 1000
Example Shaftliner Clip Attachment Schedule per UL U375
System No. System Height
Limitation
Attachment Clip Schedule
1 23 ft 10 ft o.c.
2 44 ft Base to 20 ft: 5 ft o.c.
20 ft to 44 ft: 10 ft o.c.
3 66 ft Base to 22 ft: 3’-4” o.c.
22 ft to 42 ft: 5 ft o.c.
42 ft to 66 ft: 10 ft o.c.
Attachment Clips: Aluminum or
steel angles, usually 14 – 16 gauge,
2” wide with 2” to 2-1/2” long legs.
Attaches to wall framing and H-
studs H-Stud Source: Clarkdietrich
Shaft Walls Assemblies - Shaftliner
Some wall manufacturers will
list a total system height
limitation. If this is not a
requirement of the tested
assembly (i.e. UL or sim.
requirement) can also
perform a structural analysis
of the walls, especially when
stacking multiple stories, to
verify adequacy
Source: Clarkdietrich
Shaft Walls Assemblies - Shaftliner
Wood Framed Wall on
3 Sides of Shaft
CH Studs w/Shaftliner
on 4th Side of Shaft
Shaft Walls Assemblies – Mixed
Shaft Walls Assemblies - Detailing
Credit: USG
Shaft Walls Assemblies - Shaftliner
Outline
• Shaft Enclosures
• Code Provision Review
• Assemblies
• Applications
• Individual Encasement
• Columns
• Beams
Elevator Shaft Walls
Elevator Shaft Walls
Elevator Shaft Walls
Elevator Shaft Walls
Wood Design Focus: Volume 22, Issue 3 by Smith
Rim joist
Floor joists
2 layers 5/8” thk. Type “X”
GWB each side for
2 hr. rating
Double stud
wall
Dbl. row of solid
blocking to continue
fire rating
Concrete topping
Nailer plate
WSP sht’g
as required
Elevator guide rails
and support bracket
with slotted holes
Galvanized
metal spacer
Shaft Side
Elevator Shaft Walls
Stair Shaft Walls
Stair Shaft Walls
Exterior Bearing
Wall
Intermediate Landing
Framing
Corridor Framing
Elev. = 100’-0”
Flo
or
Fra
min
g
Ele
v. =
10
0’-
0”
Indicates Downward
Stair Travel Path
Landing
Framing
Flo
or
Fra
min
g
Ele
v. =
10
0’-
0”
Structural
Beam
Stair Shaft Walls
Typical Floor
joist
Stair Framing
(Landing &
Stringers) Attachment of stair
framing to shaft wall
through gypsum, typically
2 layers
Shaft wall
Stair Shaft Walls
Typical Floor
joist
Shaft wall
Intermediate
Stair Landing
FramingAttach ledger to shaft wall stud
with fasteners (wood screws,
lag screws) designed to account
for gypsum
Stair Shaft Side
Floor Side
Stair Shaft Walls
Stair Landing
Framing
Attach ledger to studs
with fasteners (wood
screws, lag screws)
designed to account for 1
layer of gypsum
Shaft wall Blocking in shaft wall
between studs
Wall plates at typical
floor elevation
Ledger Interrupts
One Layer of Shaft
Wall Gypsum
Rationale for detail approval:
• Membranes on both sides of wall provide fire resistance via their approved assembly; at floor cavity, blocking and/or ledger in wall provides 2nd hr
Stair Shaft Side
Exterior Side
Stair Shaft Walls
Stair Landing
Framing Attach ledger to studs with
fasteners (wood screws, lag
screws)
Shaft wall
2 layers of blocking in shaft
wall between studs to
provide 2 hours protection
& ledger fastener
attachment
Wall plates at typical floor
elevationStair Shaft Side
Exterior Side
Stair Shaft Walls
Rationale for detail approval:
• Membranes on both sides of wall provide fire resistance via their approved assembly; at floor cavity, blocking and/or ledger in wall provide 2hrs
Stair Framing
(Landing &
Stringers)
Landing and stair framing
supported on
independent bearing
walls – should consider
lateral bracing of
independent walls
Shaft wall
Wall plates at typical
floor elevation
Stair Shaft SideExterior Side
Stair Shaft Walls
Bearing wall to
be protected per
Table 601
Stairway Shaft Enclosures & Framing
Exterior Bearing
Wall
Landing Framing
Elev. = 94’-8”
Corridor Framing
Elev. = 100’-0”
Flo
or
Fra
min
g
Ele
v. =
10
0’-
0”
Indicates Downward
Stair Travel Path
Landing Framing
Elev. = 100’-0”
Flo
or
Fra
min
g
Ele
v. =
10
0’-
0”
Intermediate
Landing Beam
Concentrated
Load
Intermediate
Stair Landing
Framing
Shaft wall
Stair Shaft Side
Exterior Side
Intermediate Landing Beam
Extends into Shaft Wall – Fire
caulked around structural
penetrant
Stair Shaft Walls
Wood Framed Shaft Walls
Using wood framed shaft walls can:• Eliminate lateral load considerations
associated with attaching wood
diaphragms to concrete or masonry shaft
walls (SDPWS 4.1.5)
• Eliminate differential shrinkage at floor to
wall transition
• Eliminate different construction trades in
building during construction
• Reduce costs
• Improve schedule
Outline
• Shaft Enclosures
• Code Provision Review
• Assemblies
• Applications
• Individual Encasement
Individual Encasement - Column
Individual Encasement - Column
SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.2 Column protection.
Where columns are required to have protection to achieve a fire-resistance rating,
the entire column shall be provided individual encasement protection by protecting it
on all sides for the full column length, including connections to other structural
members, with materials having the required fire resistance rating. Where the
column extends through a ceiling, the encasement protection shall be continuous
from the top of the foundation or floor/ceiling assembly below through the ceiling
space to the top of the column.
Individual Encasement - Column
SECTION 202
DEFINITIONS
PRIMARY STRUCTURAL FRAME. The primary structural frame shall include all of the
following structural members:
1. The columns
2. Structural members having direct connection to the columns including girders
beams, trusses and spandrels;
3. Members of the floor construction and roof construction having direct connections
to the columns; and
4. Bracing members that are essential to the vertical stability of the primary structural
frame under gravity loading shall be considered part of the primary structural
frame whether or not the bracing member carries gravity loads
Individual Encasement - Column
SECTION 202
DEFINITIONS
BEARING WALL STRUCTURE. A building or other structure in which vertical loads
from floors and roofs are primarily supported by walls.
FRAME STRUCTURE. A building or other structure in which vertical loads from floors
and roofs are primarily supported by columns.
Individual Encasement - Column
By definition light-frame structures do not have a primary frame.
SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.4 Protection of secondary members.
Secondary members that are required to have a fire resistance rating shall be
protected by individual encasement protection, by the membrane or ceiling of a
horizontal assembly in accordance with 711, or by a combination of both.
704.4.1 Light Frame Construction.
King Studs and boundary elements that are integral elements in load-bearing
walls of light-frame construction shall be permitted to have required fire-
resistance ratings provided by the membrane protection provided for the
load-bearing wall.
Individual Encasement - Column
SECTION 202
DEFINITIONS
SECONDARY MEMBERS. The following structural members shall be considered
secondary members and not part of the primary structural frame:
1. Structural members not having direct connection to the columns;
2. Members of the floor construction and roof construction not having direct
connection to the columns and
3. Bracing members other than those that are part of the primary structural frame.
Individual Encasement - Column
PROPOSED POLICY:
Studs, boundary elements, posts, multiple
stud groups, built-up columns and solid
columns that are framed within the wall and
do not penetrate the top or bottom plates
are all designed to the same criteria and
shall be considered integral elements. These
elements that are integral within the
confines of the load bearing wall, and do not
penetrate the top or bottom plates, shall be
permitted to be protected in light frame
construction by the membrane protection of
the fire resistance rated bearing wall.
Individual Encasement - Column
2018 IBC -SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.2 Column protection.
Where columns are required to have protection to achieve a fire-resistance rating, the entire
column shall be provided individual encasement protection by protecting it on all sides for the full
column length, including connections to other structural members, with materials having the
required fire resistance rating. Where the column extends through a ceiling, the encasement
protection shall be continuous from the top of the foundation or floor/ceiling assembly below
through the ceiling space to the top of the column.
Exception: Columns that meet the limitations of Section 704.4.1
704.4.1 Light-frame construction.
Studs, columns and boundary elements that are integral elements in walls of light- frame
construction and are located entirely between the top and bottom plates or tracks shall be
permitted to have require fire-resistance ratings provided by the membrane protection provided for
the wall
Individual Encasement - Column
Individual elements (groupings of studs or solid members) within a light frame wall assembly can not
have less fire resistance than the tested assembly itself.
2015 IBC Code and Commentary on 704.2
“Columns that provide inherent fire resistance, without encasement, such as heavy timber,
are considered as not requiring protection and do not need to comply with this section.”
Individual Encasement - Column
Individual Encasement - Column
SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.2 Column protection.
Where columns are required to have protection to achieve a fire-resistance rating,
the entire column shall be provided individual encasement protection by protecting it
on all sides for the full column length, including connections to other structural
members, with materials having the required fire resistance rating. Where the
column extends through a ceiling, the encasement protection shall be continuous
from the top of the foundation or floor/ceiling assembly below through the ceiling
space to the top of the column.
If a columns penetrates the wall plates, protection can be provided by charring effects. Protection of
connections needs to be considered.
SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.3 Protection of the primary structural frame other than columns.
Members of the primary structural frame other than columns that are required to
have protection to achieve a fire-resistance rating and support more than two floors
or one floor and roof, or support a load-bearing wall or a non load-bearing wall more
than two stories high, shall be provided individual encasement protection by
protecting them on all sides for the full length including connections to other
structural members, with materials having the required fire-resistance rating.
Individual Encasement - Beam
SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.4 Protection of secondary members.
Secondary members that are required to have a fire resistance rating shall be
protected by individual encasement protection, by the membrane or ceiling of a
horizontal assembly in accordance with 711, or by a combination of both.
Individual Encasement - Beam
SECTION 704
FIRE RESISTANCE RATING OF STRUCTURAL MEMBERS
704.3 Protection of the primary structural frame other than columns.
Members of the primary structural frame other than columns that are required to
have protection to achieve a fire-resistance rating and support more than two floors
or one floor and roof, or support a load-bearing wall or a non load-bearing wall more
than two stories high, shall be provided individual encasement protection by
protecting them on all sides for the full length including connections to other
structural members, with materials having the required fire-resistance rating.
Exception: Individual encasement protection on all sides shall be permitted on
all exposed sides provided the extent of protection is in accordance with the
required fire resistance rating as determined in Section 703.
Individual Encasement - Beam
IBC 703.3 Alternate Methods for determining fire resistance
• Prescriptive designs per IBC 721.1
• Calculations in accordance with IBC 722• Fire-resistance designs documented in sources
• Engineering analysis based on a comparison
• Alternate protection methods as allowed by 104.11
IBC 722 Calculated Fire Resistance
“…The calculated fire resistance of exposed wood members and wood decking shall be permitted in accordance with Chapter 16 of ANSI/AF&PA National Design Specification for Wood Construction (NDS).”
NDS Chapter 16 Fire Design of Wood Members
Limited to calculating fire resistance up to 2 hours.
Char rate varies based on endurance required, product type and lamination thickness. Equations and tables provided.
TR10 and NDS commentary are helpful in implementing permitted calculations.
Exposed Framing Fire Resistance
http://awc.org/pdf/codes-standards/publications/tr/AWC-TR10-1510.pdf
Source: 2015 NDS Chapter 16
http://awc.org/pdf/codes-standards/publications/nds/AWC-NDS2015-ViewOnly-1411.pdf
Exposed Framing Fire Resistance
This concludes The American Institute
of Architects Continuing Education
Systems Course
QUESTIONS?
Lisa Podesto
Senior Technical Director
WoodWorks