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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.


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.


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

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:


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:


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:


• 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


Outline

• Shaft Enclosures


• Assemblies

• Applications


• 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



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


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


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

Outline



• Assemblies

• Applications


• Columns

• Beams

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

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



• Assemblies

• Applications


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.

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


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.


By definition light-frame structures do not have a primary frame.

SECTION 704


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.


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.


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.


2018 IBC -SECTION 704



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 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.”



SECTION 704



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


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


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.


SECTION 704


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.


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

[email protected]

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