CFM 120 Light Structural Exam 1 Floor
Systems
Hardwoods - ANS Comes from deciduous trees
(broad leaves, loses leaves in winter)
Softwoods - ANS Comes from coniferous trees
(Evergreens)
Sapwood - ANS This part of the tree is new growth and is where sap flows inside the Cambium
Layer.
Heartwood - ANS This part of the tree is the dead inner wood which often comprises the
majority of a tree's cross-section. You can usually see the difference between sapwood and
heartwood because of a difference in color within the tree.
Pith - ANS Center/core of the tree
Wood Fiber - Cellulose: - ANS Wood cellulose makes up nearly 50% of woody plant mass.
Trees make cellulose to store carbon, oxygen and hydrogen. Cellulose is made up of starches,
proteins, and sugars which trees need to grow and mature.
Wood Fiber - Hemicellulose: - ANS This is carbohydrate that comprises 25% to 35% of the dry
weight of wood. It is second only to cellulose in abundance.
Wood Fiber - Lignin: - ANS This is the polymer (glue) that holds together the cellulose and
hemicellulose in trees. Lignin constitutes about 15% to 25% of the weight of wood mass.
Which is used more heavily for lumber? Soft or hardwoods - ANS Softwoods
Green Lumber - ANS Lumber when it is first cut, has high moisture content.
Lumber stops shrinking when it reaches - ANS Equilibrium
Moisture content in dry climate = - ANS No more than 15%
Moisture content in damp climates = - ANS No more than 19%
Moisture content for interior finish materials - ANS 6%-12%
, Dry Rot is a concern when moisture of the tree reaches a moisture content above _______ -
ANS 19%
Species naturally resistant to high moisture - ANS Red Cedar
Cyprus
Redwood
Pressure Treated Lumber
Lumber is processed and smoothed in the milling process until the structural lumber has been
Surfaced 4 Sides(S4S).
This changes the dimension of the material from its callout or Nominal Size to a different Actual
Size.
There is a change in actual size that is necessary to note when determining building height and
dimensions of building systems or assemblies. Such as floor systems, wall assemblies, and roof
systems. - ANS S4S because all four sides have been smoothed to protect laborers against
splinters.
Softwood actual dimensions of a 2x4 - ANS 1 1/2 in x 3 1/2in
WWPA - ANS Western Wood Products Association
WCLB - ANS West Coast Lumber Inspection Bureau
PLIB - ANS Pacific Lumber Inspection Bureau
What are the 5 parts to a Lumber Grade Stamp? - ANS Lumber Grading Association
Mill ID Number
Lumber Grade
Lumber Species
Moisture Content @ Time of Surfacing
Select Structural - ANS = at least 80% Wood
#1 Structural - ANS = At least 75% clear wood
#2 Structural - ANS = at least 66% clear wood
#3 Structural - ANS = At least 50% clear wood
("stud" grade)
Construction Grade - ANS = at least 57% clear wood
Systems
Hardwoods - ANS Comes from deciduous trees
(broad leaves, loses leaves in winter)
Softwoods - ANS Comes from coniferous trees
(Evergreens)
Sapwood - ANS This part of the tree is new growth and is where sap flows inside the Cambium
Layer.
Heartwood - ANS This part of the tree is the dead inner wood which often comprises the
majority of a tree's cross-section. You can usually see the difference between sapwood and
heartwood because of a difference in color within the tree.
Pith - ANS Center/core of the tree
Wood Fiber - Cellulose: - ANS Wood cellulose makes up nearly 50% of woody plant mass.
Trees make cellulose to store carbon, oxygen and hydrogen. Cellulose is made up of starches,
proteins, and sugars which trees need to grow and mature.
Wood Fiber - Hemicellulose: - ANS This is carbohydrate that comprises 25% to 35% of the dry
weight of wood. It is second only to cellulose in abundance.
Wood Fiber - Lignin: - ANS This is the polymer (glue) that holds together the cellulose and
hemicellulose in trees. Lignin constitutes about 15% to 25% of the weight of wood mass.
Which is used more heavily for lumber? Soft or hardwoods - ANS Softwoods
Green Lumber - ANS Lumber when it is first cut, has high moisture content.
Lumber stops shrinking when it reaches - ANS Equilibrium
Moisture content in dry climate = - ANS No more than 15%
Moisture content in damp climates = - ANS No more than 19%
Moisture content for interior finish materials - ANS 6%-12%
, Dry Rot is a concern when moisture of the tree reaches a moisture content above _______ -
ANS 19%
Species naturally resistant to high moisture - ANS Red Cedar
Cyprus
Redwood
Pressure Treated Lumber
Lumber is processed and smoothed in the milling process until the structural lumber has been
Surfaced 4 Sides(S4S).
This changes the dimension of the material from its callout or Nominal Size to a different Actual
Size.
There is a change in actual size that is necessary to note when determining building height and
dimensions of building systems or assemblies. Such as floor systems, wall assemblies, and roof
systems. - ANS S4S because all four sides have been smoothed to protect laborers against
splinters.
Softwood actual dimensions of a 2x4 - ANS 1 1/2 in x 3 1/2in
WWPA - ANS Western Wood Products Association
WCLB - ANS West Coast Lumber Inspection Bureau
PLIB - ANS Pacific Lumber Inspection Bureau
What are the 5 parts to a Lumber Grade Stamp? - ANS Lumber Grading Association
Mill ID Number
Lumber Grade
Lumber Species
Moisture Content @ Time of Surfacing
Select Structural - ANS = at least 80% Wood
#1 Structural - ANS = At least 75% clear wood
#2 Structural - ANS = at least 66% clear wood
#3 Structural - ANS = At least 50% clear wood
("stud" grade)
Construction Grade - ANS = at least 57% clear wood
