this is a presentation on engineered wood i.e psl parralel strand lumber

1. Parallel Strand Lumber
By Mrinal Dugar and Reeva Teotia
B.Arch 4th Year.
Section A
120695043
120695058

2. What is a Lumber?
• Lumber is wood in any stage from the time it is cut from a tree
through its use in construction or paper.
• Lumber is cut from a tree through a process called felling. After it is cut
and shipped, it is supplied either "rough" or "finished".
• Finished lumber is cut to standard sizes, (2x4, 2x6, etc) and is
primarily used in the construction industry. Most finished lumber is cut
from softwood trees such as pine, fir, or cedar. Some rough lumber
includes hardwoods for use in high-grade wood floors.
• Rough lumber is raw and uncut to standardized measurements. It
is used for furniture or specialty manufacturing where custom cutting
and shaping is required. Usually rough lumber is cut from trees such
as oak, and may be available in a variety of sizes for shipping. In many
instances, rough lumber will also have the bark still attached.
Rough cut lumber.
Finish cut lumber.

3. What exactly is PSL?
• Parallel strand lumber (PSL) is a high strength structural composite lumber product
manufactured by gluing strands of wood together under pressure.Because it is a glued-
manufactured product, PSL can be made in long lengths but it is usually limited to 20m (66
ft.) by transportation constraints.the strand elements with wood fibres are primarily
oriented length wise.
AVAILABLE SIZES IN THE MARKET:-
• least dia. of the strands must not exceed 6.4 mm. and the avegare length is 150 times the dia.
(min.).
• The product is manufactured as a 12" x 12" or 12" x 18" billet in a rectangular cross-
section, which is then typically sawn and trimmed to smaller cross-sectional sizes
• Typical thicknesses are 3½", 5¼” or 7"; typical depths are 9½", 11⅞" 14", 16" & 18". Typically
the beams are made to a maximum length of 60 feet.

4. PSL Manufacturing Process.
• PSLs are made of long, thin strips of wood (usually Douglas fir or hemlock) that are
coated with high-strength waterproof resin glue; aligned so that the strips are
parallel; formed into large billets that are pressed to their proper thickness; and
heated to cure the glue. One manufacturer uses microwaves to cure the PSL instead of
heat from conventional fuel. The billets of PSL are then sawn to form beams in the same
dimensions as those sawn from logs. The result is straight, stable beams that can be
purchased in lengths as long as 44 feet. These are of uniform strength and density
throughout. The manufacturing process reduces the waste from each log to less than
1/3 of its volume.
• Manufactured at a moisture content of 11 percent, which is approximately the equilibrium
moisture content of wood in most service conditions, PSL is less prone to shrinking,
warping , cupping, bowing or splitting.

5. • It is made from southern pine from wood strands from which the
growth imperfections have been removed. This results in a product
having consistent properties and high load carrying ability.
• Douglas Fir (DF) and Southern Yellow Pine (SYP) are the most commonly
used wood species
• If boards or beams can be found that are longer than 16 feet, they are
often not straight enough or strong enough to use for floor joists,
rafters, or load-bearing studs.
The formation of
strands and then
being parallel
glued over each
other.

6. Uses of PSL.
• PSL is well suited for use as beams and columns for post and beam construction, and for beams, headers,
and lintels for light framing construction.
• It is commonly used for heavily loaded columns, and beam and header applications where high
bending strength is needed.
• PSL is suited to applications where finished appearance is important. It is also suited to concealed
structural applications where appearance is not a factor.
• PSL readily accepts preservative treatment and a very high degree of penetration and therefore protection is
possible. Treated PSL should be specified for members which will be directly exposed to high
humidity conditions.
• Beams, purlins/rafters, columns
• - Timber-frame constructions

7. Pepsico
factory
rooftop load
bearer.
Outer
fascade glass
glazing
support.
Australia
expo mart
glass
support.
Load
distributing
connecting
joints
Column nad
beam joints
Uses in different
forms and
structures.

8. Types of defects in PSL.
• Defects occurring in lumber are grouped into the following four divisions
• Conversion
During the process of converting timber to commercial form the following defects may occur:
• Chip mark
this defect is indicated by the marks or signs placed by chips on the finished surface of timber
• Diagonal grain
improper sawing of timber
• Torn grain
when a small depression is made on the finished surface due to falling of some tool
• Wan
presence of original rounded surface in the finished product

9. Defects due to fungus
• Fungi attack timber when these conditions are all present:
• The timber moisture content is above 25% on a dry-weight basis.
• Wood with less than 25% moisture (dry weight basis) can remain free of
decay for centuries. Similarly, wood submerged in water may not be
attacked by fungi if the amount of oxygen is inadequate.

10. BLUE STAIN DEFECT DRY ROT DEFECTBROWN ROT DEFECT HEART ROT DEFECT
SAP STAIN DEFECT WET ROT DEFECT WHITE ROT DEFECT SEASONING DEFECT
FUNGAL DEFECTS

11. Advantages of using PSL.
• The advantages of SCL are high strength,
flexibility of sizes and shapes, stiffness, and
excellent treatability with preservatives.
• High stress
• More consistency for strength performance and
stability, due to lamination.
• It satisfies environmental concerns.
Psl core

12. Adhesives used and available in market.
The types of adhesives used in engineered wood include:
• Urea-formaldehyde resins (UF) most common, cheapest, and not waterproof.
• Phenol formaldehyde resins (PF) yellow/brown, and commonly used for exterior
exposure products.
• Melamine-formaldehyde resins (MF) white, heat and water resistant, and often
used in exposed surfaces in more costly designs.
• Methylene diphenyl diisocyanate (MDI) or polyurethane (PU) resins
• expensive, generally waterproof, and does not contain formaldehyde.

13. Uses of PSL in column and beams according
to span and load distribution.