1. Structural Composite Lumber & Glued Laminated Timber
Awareness Guide
Ray O’Brocki, CBO
Manager - Fire Service Relations
American Wood Council

2. Purpose of this guide
The purpose of this awareness guide is to provide the fire service with information on the types and properties of Structural Composite Lumber (SCL) and Glued Laminated Timber (Glulam), how the products are manufactured, and how they are used in residential construction.

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8. Upon completion, participants will be better able to identify:
Learning Objectives
Upon completion, participants will be better able to identify: 1
Structural Composite Lumber 3
Manufacture
Identify methods for the manufacture of SCL and Glulam
Identify the types and applications of structural composite lumber (SCL) 2
Glued laminated Timber 4
Site Visits
Be able to identify Glued Laminated Timber (Glulam) and its applications
What to look for when visiting a residential construction site and examining the framing

9. Structural Composite Lumber (SCL)
Rectangular shape
Superior strength, stiffness, and consistency
Manufacturing
smaller logs
sort the pieces
apply adhesive
reassemble
Popularity
long and wide dimensions
without warp
SCL products are well known throughout the construction industry as a rectangular shaped product that has superior strength, stiffness, and consistency. Advancements in technology have given SCL manufacturers the ability to take apart a smaller log, sort the pieces, apply adhesive and reassemble them back together into an engineered product that has enhanced product performance. SCL products have grown in popularity because of the availability of long and wide dimensions without warp.
Parallel Strand Lumber and Laminated
Veneer Lumber

10. Types of structural composite lumber
Laminated Veneer Lumber (LVL)
Parallel Strand Lumber (PSL)
Laminated Strand Lumber (LSL)
Oriented Strand Lumber (OSL)
SCL is a general term for a variety of engineered wood products. There are several acronyms to describe structural composite lumber based on the size and shape of the wood pieces that are adhered together.
Laminated veneer lumber is placed into a metal hanger and
supported by another LVL girder.

11. Laminated Veneer Lumber (LVL)
Applications
Beams
Lintels
Purlins
Truss Chords
Girders
Headers
Manufacture almost any length
Strength of solid timber, concrete and steel
LVL headers are commonly used to span large openings, such as this window

12. Laminated Veneer Lumber (LVL)
LVL Manufacturing
Rotary peeling method
knife parallel to edge of a log spinning on a lathe
similar to removing paper towels from a roll
individual cut sheets called veneer
dried
glued
pressed together
Plywood is made by a similar process
The manufacturing process for all SCL typically includes sorting and aligning the strands or veneer, applying adhesive, and pressing the material together underheat and pressure.
LVL is manufactured using the Rotary peeling method.
Rotary peeling uses a knife placed parallel to the out-side edge of a spinning log on a lathe. The wood is peeled off the log starting on the outside and working towards the center, similar to removing paper towels from a roll. The wood slices are then cut into individual sheets called veneer, dried, glued, and pressed together to form the product.
Plywood is made by a similar process.
Laminated veneer lumber is available in a variety of widths and depths generally to match I-joist depths

13. Laminated Veneer Lumber (LVL)

14. Laminated Veneer Lumber (LVL)
Bay window headers support a small roof
LVL header supports floor joists above and exterior wall and roof
Lumber floor joist cavities filled with batt insulation
Multi-ply LVL girder bolted together at regular spaces

15. Laminated Strand Lumber (LSL)
Applications
Rim boards, millwork
Window, door and garage headers
Resembles Oriented Strand Board (OSB)
Made from long strands using stranding manufacturing process
Laminated veneer headers are commonly used to span large opening,
such as this window opening.

16. Laminated Strand Lumber (LSL)
Stranding
3-inch to 12-inch slices
similar to grating a block of cheese
Strands dried in large rotary drum
Adhesive applied
Strands dropped into forming bin
Pressed together
thin and flat sheets like plywood
long and wide like sawn lumber
Stranding slices the entire log into 3-inch to 12-inch
strands, similar to grating a block of cheese. The strands
are dried in a large rotary drum, where an adhesive is
applied. The strands are then dropped into a forming bin
and pressed together to form the individual products.
These products can be thin and flat sheets, like plywood,
or long and wide, like sawn lumber.

17. Laminated Strand Lumber (LSL)

18. Parallel Strand Lumber (PSL)
Structural applications
Beams
Columns
Headers
Lintels
Attractive appearance
Used where finished appearance is a factor
Manufactured using stranding method
PSL is a high strength SCL product manufactured by gluing wood strands together under pressure

19. Parallel Strand Lumber (PSL)

20. Parallel Strand Lumber (PSL)
Fabricated from veneer slices
Combined with adhesive
Formed into large billets
Sawn into more useable dimensions
Voids result from random strand lay-up
Makes preservative treatment possible

21. Parallel Strand Lumber (PSL)
PSL available in variety of shapes for use as columns and girders
PSL supports I-joist floor assembly sheathed with OSB

22. GlueD Laminated Timber (Glulam)
Fabrication
nominal 1- to 2-inch thick KD lumber
laminated under controlled temperature and pressure
form large timber sections
Glulam Girder

23. Glued Laminated Timber (GLULAM)
Straight or arched long-spans
Required strength/position of each lam
predetermined through engineering analysis
Tension and compression (outside) lams
higher-grade lumber
carry much of the bending load
Core lams equally important
resist horizontal shear stresses
Thermosetting adhesives
adhesives undergo irreversible chemical change when first heated under pressure
Glulam can be fabricated in almost any straight or arched configuration for long spans. Glulam is
manufactured with laminate layers (called lams), glued together. The required strength and position of each lamination is predetermined through engineering analysis. The tension and compression (outside) lams are made of higher-grade lumber and carry much of the bending load. However, the core lams are equally important as they resist the horizontal shear stresses. Individual lams are formed by cutting kiln-dried lumber into pre-determined thicknesses. For glulam, the lams are then joined together using thermosetting adhesives. These adhesives undergo irreversible chemical change when first heated under pressure.
Glulam Girder

24. Glued Laminated Timber (GLULAM)
Retains traditional look of wood along with engineered strength
Glulam used in a roof truss

25. Fire Performance of SCL and GLULAM
Glulam and SCL, although composed of smaller pieces of wood that are adhered together, offer the same fire performance as sawn members of similar size because the adhesives used in their manufacture does not adversely affect fire performance.*
Glulam and SCL, although composed of smaller pieces of wood that are adhered together, offer the same fire performance as sawn members of similar size because the adhesives used in their manufacture does not adversely affect fire performance.*
*Malhotra, H. and Rogowski, F., “Fire Resistance of Laminated
Timber Columns,” Proceedings of Symposium No. 3. Her Majesty’s
Stationary Office, London 1970, pp
Glulam Header
Courtesy of APA-The Engineered Wood Association

26. Fire Performance of SCL and GLULAM
The fire performance of timber can be attributed to the charring effect of wood. As wood members are exposed to fire, an insulating char layer is formed that protects the core of the section. Beams and columns can be designed with a sufficient cross section to sustain the design loads for the required duration of fire exposure in the ASTM E 119 Test.*
*”ASTM E Standard Test Methods for Fire Tests of Building
Construction and Materials,” in ATSM Test Standards, Philadelphia, PA, 1993, pp
LVL and plywood construction
Courtesy of APA-The Engineered Wood Association

27. Courtesy of APA-The Engineered Wood Association
What is the ASTM E 119 Test?
Intended to evaluate duration for which types of building elements contain a fire, and retain structural integrity during predetermined test fire
Pass/Fail Criteria based on peak temperature attained at back of test assembly or material
Whether test assembly or material distorts or collapses and allows hot gases to escape
Whether wall can withstand hose stream pressure
The test is intended to evaluate the duration for which the types of building elements contain a fire, retain their structural integrity during a predetermined test fire.
The Pass/ Fail Criteria is based upon the peak temperature attained at the back of the test assembly or material;
And/or whether the test assembly or material distorts or collapses that allows hot gases to escape, and;
Whether the wall can withstand the pressure of a hose stream
Glulam beam floor
Courtesy of APA-The Engineered Wood Association

28. SCL used as roof ridge beam
Site visits
During construction
best time to see how SCL or glulam systems configured to carry loads
Large dimension members
floor or roof beams
headers over doors and windows
rim board around foundation edges
Wall framing studs
During construction is the best time to see how an SCL or glulam framing system is configured and carries loads. These large cross-section dimension members can be used almost anywhere, and typically are installed as floor or roof beams, headers over doors and windows, rim board around the edge of a foundation, or as studs in wall framing
SCL used as roof ridge beam

29. SCL used as header and blocking
Site visits
Residential construction
built from ground up
Framing inspection
from roof down
Although residential construction is built from the ground up, framing is best inspected from the roof down. The most important structural characteristic common to all buildings and all types of construction is referred to as “load path continuity.” Load path is the prescribed route that gravity loads—such as live, snow, and water ponding—and lateral loads—from wind and earth-quakes—follow to the footings. For simple single-family dwellings, the roof, ceiling and floor loads are collected through rafters or joists, which rest on exterior walls, and interior beams or bearing walls
SCL used as header and blocking

30. SCL used as header and blocking
Site visits
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
Although residential construction is built from the ground up, framing is best inspected from the roof down. The most important structural characteristic common to all buildings and all types of construction is referred to as “load path continuity.” Load path is the prescribed route that gravity loads—such as live, snow, and water ponding—and lateral loads—from wind and earth-quakes—follow to the footings. For simple single-family dwellings, the roof, ceiling and floor loads are collected through rafters or joists, which rest on exterior walls, and interior beams or bearing walls
SCL used as header and blocking

31. SCL used as header and blocking
Site visits
Simple single-family dwellings
roof, ceiling and floor loads
collected through rafters or joists
rest on
exterior walls
interior beams
bearing walls
Although residential construction is built from the ground up, framing is best inspected from the roof down. The most important structural characteristic common to all buildings and all types of construction is referred to as “load path continuity.” Load path is the prescribed route that gravity loads—such as live, snow, and water ponding—and lateral loads—from wind and earth-quakes—follow to the footings. For simple single-family dwellings, the roof, ceiling and floor loads are collected through rafters or joists, which rest on exterior walls, and interior beams or bearing walls
SCL used as header and blocking