Lesson 10
Roofing
Agricultural
Structures
Next Generation Science/Common Core Standards Addressed!
 CCSS.ELA Literacy Cite specific textual evidence to support analysis of
science and technical texts, attending to the precise details of explanations or
descriptions..RST.9‐10.1
 CCSS.ELA Literacy.RST.11‐12.3 Follow precisely a complex multistep
procedure when carrying out experiments, taking measurments,or performing
technical tasks; analyze the specific results based on ex HSNQ.
 HSNQ.A.1 Use units as a way to understand problems and to guide the
solution of multi‐step problems; choose and interpret units consistently in
formulas; choose and interpret the scale and the origin in graphs and
Student Learning Objectives/Bell Work
Explain the application of
asphalt and fiberglass roofing
materials.
Explain the application of
metal roofing materials.
Terms
Drill screws
Ridge
Flashing
Ridge cap
H-clips
Ridge vent
Metal drip edge
Ring or screw-
Pipe flashing
shank roofing
mails
Rolled roofing
Roof vents
collar
Plastic cap nails
Purlins
Terms
Roofing felt
Selvage-edge roll roofing
Shingle
Smooth-surfaced roll roofing
Straight blade utility knife
Wood shingles
Interest Approach
What kind of roof do you have
on your house?
How was it secured down
(nailed, screwed, fastened)?
What is a shingle?
A shingle is the individual
roofing unit made of slate,
wood, asphalt, or fiberglass.
The shingles used today are
almost all three tab sealdown asphalt or asphaltfiberglass combination
shingles.
What is a shingle?
In the early years of this
country, most roofs were
covered with wood or slate
shingles.
The Roofing Process
Regardless of the type of shingle
used, roofing starts with the
covering of the rafters or trusses
with roof sheeting.
The Roofing Process
1st - H-clips are metal brackets shaped like
an H installed between each set of rafters
where two pieces of sheeting meet.
The clip helps strengthen the joint.
Roofing Process
2nd - Metal drip edge,
commonly called T-tin because
of its shape, is nailed in place
at the outer edges of the roof.
Roofing Process
3rd - Cover the sheeting with
roofing felt.
Roofing felt is an asphalt
saturated felt that comes in
a roll.
Most common thickness
used are 15 & 30 lbs.
– Straight blade utility knife is a
retractable triangular pointed
knife that works well to cut
the felt.
Roofing Process
4th - Plastic cap nails are used
to nail on the felt.
Plastic cap nails have a one
inch diameter cap on a ring
shank nail.
– When the wind blows, the felt is less
likely to blow off than if regular roofing
nails are used.
Wood Shingles
Wood shingles give a natural
rustic look to a building but are
very expensive and rarely
used on agricultural buildings.
Wood Shingles
Usually Cedar or other rot
resistant wood is cut in a
beveled 16 inch long piece
with an approximate ½ inch
base thickness.
 They are sold by the
thousand or in bundles of 250
each.
Asphalt Roofing Materials
Rolled roofing is a three foot wide and 36
foot long roll.
Rolled roofing is not as attractive as shingles
and has a shorter life expectancy, but is
cheaper.
Asphalt Roofing Materials
Smooth-surfaced roll roofing is
used in a single coverage type
installation where it is
overlapped only a few inches.
Today’s Shingles
Most shingles
used today are
three tab sealdown asphalt or
asphaltfiberglass
combination
shingles.
Metal Roofing
Metal has gradually replaced
asphalt and asphalt-fiberglass
shingles in many agricultural
buildings especially when the
pole-type or rigid-arch type
buildings are built.
Metal Roofing
While metal roofing is noisy in a
rain storm and not as attractive as
shingles, it is fire resistant,
cheaper, and much easier and
faster to install.
Metal roofing will be either steel or
aluminum sheets.
Installing Metal Roofing
With metal roofing after the rafters
or trusses are in place, horizontal
nailing boards called purlins. Metal
perlins are actually more common in
NM.
Installing Metal Roofing
Purlins are installed to attach
the roofing sheets.
The purlin spacing depends
on the type and thickness of
the roofing sheets.
Metal roofing is installed in a
particular order.
Installing Metal Roofing
 Ridge Cap or Ridge Vent is installed to allow warm
moisture to escape.
 Metal roofing may be fastened with ring or screwshank nails.
– Ring or screw-shank roofing nails have a lead,
neoprene, or rubber washer to prevent leakage
and rings or screws to prevent the nail from
popping out over time.
– Metal screws with a rubber washer may be used
on wood or metal perlin.
All metal agricultural structures are more common and
economical in the southwest US as the metal may be more
inexpensive than wood. Metal is often faster to assemble.
Metal roofing is attached to metal perlin using TEK screws.
 Lap Screws
Perlin Screws
Common Metal Perlin
Comparison of
Types of Metal Roofing
While steel sheets are
stronger than aluminum they
are subject to rust.
To prevent rust,steel can be
purchased with a baked on
enamel paint or a galvanized
coating.
Comparison of
Types of Metal Roofing
Galvanized steel roofing
comes as corrugated sheets
with a zinc coating.
Aluminum Roofing
Aluminum roof sheeting will
not rust but is expensive, thin,
and easily damaged.
Buildings covered with
aluminum must have nailing
boards with closer spacing
than for galvanized steel.
Corrugated Roofing
Corrugated roofing is made
from flat sheets that have been
formed into a series of
alternate ridges and grooves,
or hills and valleys, that run in
the same direction.
Corrugated Roofing
The corrugations give the
sheets a greater stiffness,
increased load-carrying ability,
and prevent water siphoning
between the sheets into the
building.
Review/Summary
What are the kinds of
materials used to roof
agricultural buildings?
What different practices are
used when installing a metal or
aluminum roof?
The end!