Awareness Guide Ray OBrocki CBO Manager Fire Service Relations American Wood Council Purpose of this guide The purpose of this Awareness Guide is to provide the fire service with information on the types and properties of wood Ijoists how they are manufactured and how they are used in re ID: 786513
Download The PPT/PDF document "WOOD I-JOISTS & FIREFIGHTER SAFETY" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
WOOD I-JOISTS & FIREFIGHTER SAFETY
Awareness Guide
Ray O’Brocki, CBOManager- Fire Service RelationsAmerican Wood Council
Slide2Purpose of this guide
The purpose of this Awareness Guide is to provide the fire service with information on the types and properties of wood I-joists, how they are manufactured and how they are used in residential construction. It is important that the fire service understand the unique characteristics of wood I-joists and recognize their unique installation requirements.
Slide3About AWC
Codes and Standards
Sustainability
Manufacturing Environmental Regulation
Advocacy and Public Policy
Slide4Education Resources
www.awc.org
Education Tab
Slide5To expedite your CEUs, create an account on our website!
www.awc.org
Slide6Education Resources
www.awc.org/education
education@awc.org
In-Person Seminars
Monthly Webinars
Recorded Presentations
CEUs Available
Slide7Code Official Connections
www.awc.org/codeconnections
membership@awc.org
Free to Qualified Officials
Free Standard
Pubs Discounts
WoodPost
Newsletter
WoodWorks Software
Slide8Learning Objectives
Upon completion, participants will be better able to identify:
Identify the types and applications of I-Joists
I-Joists
Be able to identify where I-joists are most commonly used and take proper precautions
Firefighter Safety
Identify the method for the manufacture of I-Joists
Manufacture
What to look for when visiting a residential construction site and examining the framing
Site Visits
1
3
2
4
Slide9What is a Wood I-Joist?
Shaped like the letter “I”
Two horizontal components – flanges
Vertical component – web
Used primarily in floors
Also roof rafters
Long lengths and high load capacities
Slide10I-Joist Components
Close tolerance between individual components
Flanges
Solid sawn lumber
Structural composite lumber (SCL)
Webs
Oriented strand board (OSB)
Sufficient thickness to transfer loads to flanges
Slide11I-Joist Installation
Holes/Openings
Cut in the web
Allow ducts/utilities through I-joist
Must strictly follow
Manufacturers’ recommendations
Applicable building codes
Slide12Builder Appeal
Uniform dimensions
Lightweight
Long span capability
Slide13Types of I-Joists
1980s
Plywood web
Sawn-lumber flanges
1990s
OSB web
SCL flanges
Laminated veneer lumber (LVL)
Laminated strand lumber (LSL)
Slide14I-Joist Manufacturing
Web
Cut to proper rectangular shape
Edges shaped to match flange groove
Continuous process
Web edges glued
Inserted into flanges
Pressed together
Cut to length
Cured in special ovens
Develop full adhesive strength
Slide15I-Joist Use in residential construction
Depths 9-1/2 to 16 inches
Single continuous span often used
Efficiencies during construction
End-supports
Beams
Bearing walls
Intermediate supports
If needed
I-joist floor assemblies can bear on girder and column system as shown in this SF dwelling
Slide16Important performance characteristics
Strength and Stiffness
Capacity to carry design loads without Failing
Deflecting beyond specified limits
Glulam and I-Joist construction
Fife, Washington
Courtesy of APA — The Engineered Wood
Association
Slide17Important performance characteristics
Connections
Ensure proper load transfer
Gravity
Wind
Earthquakes
To the foundation
Glulam and I-Joist construction
Fife, Washington
Courtesy of APA — The Engineered Wood
Association
Slide18Important performance characteristics
Modifications
Holes for mechanicals
Published hole charts (see manufacturers’ literature)
Structural analysis
Repair or manufacturer evaluation
Holes that are too large
Flange damage
Glulam and I-Joist construction
Fife, Washington
Courtesy of APA — The Engineered Wood
Association
Slide19Important performance characteristics
Occupant Considerations
Not required in building codes
Evenness of floors
Vibration
Bounce
Floor system feel
Often important design consideration
Glulam and I-Joist construction
Fife, Washington
Courtesy of APA — The Engineered Wood
Association
Slide20Is it an I-Joist or Truss?
Often thought of as being the same
Design and installation requirements uniquely different
Parallel chord trusses
I-joists and LVL girder
Slide21I-Joist & Truss Similarities
Similarities
Share common component names
top and bottom chords (flanges)
Make efficient use of wood fiber through design
Duct work easily routed through parallel chord truss floor assembly
I-Joist Floors: Courtesy of
APA — The Engineered Wood Association
Slide22I-Joist & Truss Differences
Differences
I-joists – fixed design properties
Trusses – project-specific design
I-joists – adhesives
Trusses – metal connector plates
I-joists – deep (tall) webs require blocking
Trusses – long truss webs require bracing
I-joists – distribution channels allow long-distance shipping to job sites
Trusses – regional manufacturing
Courtesy of APA – The Engineered
Wood Association
Slide23General Construction practices
I-joists installed similar to sawn lumber floor joists
Also used as roof rafters
Careful attention to connection details and framing configuration
Bridging can be used to increase stiffness and reduce bounce and vibration
Slide24General Construction practices
I-joists must be held vertically where supported by a beam
Achieved with blocking or joist hangers
Special attention to connectors during installation
I-joist floor assembly viewed from the
floor below
Slide25General Construction practices
I-joists used as roof rafters for high, open ceilings
No ceiling joists resist outward thrust
I-joists supported at both ends
LVL ridge beam
Wall top plate
Ridge beam load
Carried by columns to foundation
Slide26General Construction practices
Similarities to traditional solid sawn assemblies
ends capped with rim joist – holds joist vertical and transfer loads from wall above
rim joist attached to sill plate that is bolted/strapped to foundation
Slide27Site visits
I-Joist Floor Framing
D
etail
Residential construction
built from ground up
Framing inspection
from roof down
Slide28Site visits
I-Joist Floor Framing
D
etail
Load path continuity
most important structural characteristic common to all buildings/construction
route that loads follow to footings
gravity
live, snow, and water ponding
lateral loads
wind and earthquake
Slide29Site visits
I-Joist Floor Framing
D
etail
Simple single-family dwellings
roof, ceiling and floor loads
collected through rafters or joists
rest on
exterior walls
interior beams
bearing walls
Slide30Site visits
I-Joist used as roof rafters
Pre-planning or Training
Layout drawings
Spacing
Connection specification and location
Proper bearing
Walls, girders, or joist hangers
Web stiffeners
Attached where specified
Hangers
Manufacturers requirements
Nail in every hole?
Screws typically not permitted as nail replacement
Field modifications
Wiring, plumbing, HVAC
Manufacturer’s recommendations
Slide31Fire Incidents with I-Joists
Exposed I-Joist Floor
System
Courtesy of APA — The Engineered Wood Association
Fire incident reports
Direct fire exposure (unprotected)
Strength loss often occurs with floor sheathing burn-through
I-joist web consumed first
Bottom flange falls from system
Resulting floor systems
Remain intact
Over 12" deflection
Firefighters
Felt a floor become "soft" or "spongy"
Visually observed deflection
Exited the structure
Slide32One of many Modern home features
Feature
Larger Homes
Open Floor Plans
Increased Fire Loads
Floor/Ceiling/Attic Voids
New Building Materials
More Synthetics in Furniture
Fire Behavior Effect
Faster Fire Propagation
Shorter Time to Flashover
Shorter Escape Times
Shorter Time to Structural Collapse
Source: UL University - Structural Stability of Engineered Lumber in Fire Conditions - Underwriters Laboratories
Slide33UL Fire Testing: Floor systems
Source: UL University - Structural Stability of Engineered Lumber in Fire Conditions - Underwriters Laboratories
Test
Protected or Unprotected
Time to Collapse
(min:sec)
2x10
16”
o.c.
Unprotected
18:45
12” deep I-Joist
24”
o.c.
Unprotected
6:03
2x10
16”
o.c.
Protected with
½” GWB
44:45
12” deep I-Joist
24”
o.c.
Protected with
½” GWB
26:45
Slide34Fire Protection of floors - IRC
R302.13 Fire protection of floors
. Floor assemblies that are not required elsewhere in this code to be fire-resistance rated, shall be provided with a
1/2-inch gypsum wallboard membrane
, 5/8-inch wood structural panel membrane, or equivalent
on the underside of the floor framing member
. Penetrations or openings for ducts, vents, electrical outlets, lighting, devices, luminaires, wires, speakers, drainage, piping and similar openings or penetrations shall be permitted.
Exceptions:
Protected by an NFPA 13D system
Floor assembly directly over a crawl space w/o storage of heating appliances
Aggregate area doesn’t exceed 80ft
2
or fireblocking separates unprotected portion from remainder of floor assembly
Floor assemblies using dimensional or structural composite lumber 2x10 or greater
Slide35Fire suppression considerations
Assume houses built after 1990 utilize I-Joist floor and roof systems
Floor collapse firefighter fatalities primarily occur over basements
Consider not putting firefighters directly on roof – work off aerial ladders
Vent through natural openings e.g. skylights and scuttles
Basement fire with exposed
ceilings
I-joists
– do not conduct interior attack unless
incipient fire stage
human life is at stake
fire can be extinguished quickly
Floor/ Roof failure is unpredictable and can occur with little or no warning
DO NOT LET LACK OF HEAT FOOL YOU
!
UL Testing revealed temperature difference above and below floor/roof system can be 968-1221˚F 30 seconds before collapse
Source: UL,
Report on Structural Stability of Engineered Lumber in Fire Conditions, Underwriters Laboratories
, Sept. 2008. Pg. 104
Slide36