2. Roofing Systems
073000 Steep Slope Roofing
Shingles and Shakes
Roof Tiles
Natural Roof Coverings
074000 Roofing and Siding Panels
Roof and Wall Panels
Siding
075000 Membrane Roofing
076000 Flashing & Sheet Metal
077000 Roof and Wall Specialties and Accessories
3. Division 7
078000 Fire and Smoke Protection
079000 Joint Protection
Joint Sealants and Expansion Control
4.
5. Low Slope - Disadvantages
• water drains slowly
• standing water can cause deterioration
• structural movement - tear the
membrane.
6. Low Slope - Advantages
• can cover building of any horz. dimension
can serve as
• balconies, decks, patios, landscaped gardens.
7.
8. Name: Kallen Hawthorne ID# 10596914
Item Spotted: Flat roof
Observations: This is not a
good roof design for wet
climates. There is constantly
puddles of water on the top
of this roof.
Location: PEB, WSU
Campus
9. Steep Slope
• drains quickly
• can be covered with roofing material of
small overlapping units
- shingles of wood
- slate
- artificial composition
- tiles of fired clay or concrete
- bundles of reeds (thatch).
10. Steep Slope
• Thermal expansion / contraction minimized
• Movement in structure is minimized
- by the ability of small units to move with
- respect to one another.
• Water vapor vents from the interior through
the loose joints in the roofing material.
11. Name: Kallen Hawthorne ID# 10596914
Item Spotted: A
combination of a flat and
gamble roof
Observations: This
building has a very
interesting skyline because
of the combination roof.
However if one was to
look closely at the picture,
one con see puddles of
standing water.
Location: Smith Gym,
WSU Campus
12.
13.
14.
15. LOW SLOPE ROOF
(not FLAT) < 3:12 pitch
• Min Slope
• 1/8” per 1’-0” or 1:100
• 1/4” per 1’-0” or 1:50
17. Roof Slope
• Slope Roof to direct water towards drainage
points
- counter-acting structural deflection.
• Depending on size of deck expansion joints
should be provided to
- control expansion and contraction and
- satisfy requirements of membrane.
• Membrane should be laid on flat surface.
19. Deck:Types of structural deck
used for low slope roof
• Plywood over wood joists
• Solid wood decking over heavy timber framing
• Corrugated steel decking
• Panels of wood fiber bonded together with
portland cement
• Poured gypsum over insulating formboard
• Sitecast concrete and precast concrete
20.
21.
22. Insulating Deck Boards – wood/glass fibers
Truss Tee Purlins + slab of gypsum/lt wt conc
24. Thermal Insulation:
Below the Deck
• Leaves the deck and membrane exposed to
full range of temperature.
• Batt insulation of glass fiber or mineral
fiber between wood joists
- or on top of a suspended ceiling assembly.
• Vapor retarder below insulation**
(Vapor retarder on warm side of insulation)
25. Insulation: Between Deck and
Membrane
• Rigid panels of insulation, light weight concrete.
• Protects deck from temperature extremes.
• Membrane subjected to extreme temperature
variations.
• Moisture trapped in insulation can damage
insulation and deck.
• Place vapor retarded on inside of insulation and
vent insulation to release moisture.
26. Insulation: Above the Membrane
• Membrane protected - extremes of temperature.
• Membrane on warm side of insulation - immune to
vapor blistering.
• Insulation must be a material which is not effected
by wet and will not disintegrate - extruded
polystyrene board
• Insulation board adhered in bed of hot asphalt or
laid loose.
• Layer of ballast laid over insulation.
27. Insulation: Above the Membrane
• Ballast
- crushed stone
- thin concrete layer factory laminated to upper
surface of insulation board
- interlocking concrete blocks.
• Membrane ages little protected from sunlight and
temperature extremes - despite presence of
moisture.
• Rigid insulation - mechanical fix to deck
preferable.
28. Insulation above the Membrane:
Other names for this system
• Inverted roof
• Upside down roof
• Protected membrane roof,
+- 20years old
29. Vapor Retarder
• 2 sheets asphalt saturated roofing felt
• In cold climate on warm side of
insulation.**
• In hot humid climate/with air conditioning -
on outer side of insulation**
30. Membrane
• Built up roof membrane
• Single-ply roof membrane
• Fluid-applied roof membrane
31. Built-up membrane
• 2-4 Layers/ plies of felt
asphalt impregnated, bedded in bitumen
felt: cellulose fibers/glass fibers +asphalt
• Felt laminated in overlapping layers
• Layer of aggregate (crushed stone)
32. Built-Up Membrane
• Bitumen - asphalt derived
• For low pitch roofs - coal tar bitumen or
coal-tar pitch used-
- greater resistance to standing water
• Asphalt and coal tar are applied hot
40. Built-Up + Single Ply
Ballast
• loose stone aggregate
• precast concrete blocks.
• Ballast holds the membrane in place against
wind uplift
• Protects membrane from ultraviolet light
and physical wear.
• Increase the fire resistance of the roof
covering.
41. Traffic Decks-walks, terraces,
parking – on low slope roof
(a) Heavy square paving slabs or stones –open joints
on blocks of plastic or conc on roof membrane
(b) Open Jointed Paving Blocks on A drainage layer
of gravel or porous concrete leveled over the
membrane
• Water falls through the joints and is drained
away by the membrane below
• Membrane is not pierced.
42. Structural Standing Seam
Metal Roofing for Low Slope
Roofs:
• Proprietary systems of standing seam metal
roofing
• Used as low slope roofs - 1/4" in 12 "(1:48).
• The folded shape - stiffness - support itself +
a normal snow load between purlins without
the need for structural deck below.
57. Steep Slope >3:12 pitch
• Drains quickly,
• Small overlapping units - Shingles
• Expansion and contraction and
movement
• Water vapor vents
58. Steep Slope Roof – Systems
3 Categories of Covering
• Thatch
• Shingles – wood, asphalt, slate, clay/conc
• Sheet Metal – lead, copper, terne, aluminum
59. Steep Sloped Roof Systems
• Typically insulation and vapor retarder
installed below the roof sheeting or deck.
• Underside of deck is exposed as a finished
surface
- vapor retarder and rigid insulation above
the deck below roofing layer of plywood
(nailed over the insulation panels as a nail
base for fastening shingles or sheet metal).
63. Thatch
• Bundles of reeds, grasses or leaves,
• Labor intensive
• Highly insulative
• Attractive
• Codes limit its use
• Not fire resistant
64.
65. Shingles
Small size unit, applied to roof in overlapping
layers - staggered vertical joints
• wood shingles/ shakes
• asphalt shingles
• slates
• clay tiles and concrete tiles.
• PV – photovoltaic
66. Shingles
• Each type of shingle, slate or tile must be
laid on a roof deck - that slopes sufficiently
to assure leak-proof performance.
• Min. slope for each material are specified
by the manufacturer and code
67. Wood Shingles:
• Thin, tapered slabs of wood, SAWED from
short pieces of tree trunk
• Grain parallel to the face of the shingle.
68.
69.
70. Wood Shakes
• Split not sawn
• Rough face texture,
• North US - wood shingles/ shakes are Red
cedar, White cedar,
• Redwood - natural decay resistance.
• Wood roof covering moderately expensive,
not highly resistant to fire unless pressure
treated with fire retardant chemicals.
71.
72. Asphalt Shingles
• Asphalt impregnated felt - faced with mineral
granules.
• Die cut from sheet, typical size 12" x 36".
• Slotted twice - smaller unit.
• Inexpensive, quick to install, moderately fire
resistant.
• Expected life time of 15 to 25 years.
• Laid on asphalt saturated felt paper in two layers.
73.
74.
75.
76.
77.
78.
79. Slate
• Split, trimmed to size and punched or
drilled for nailing.
• Fire resistant,
• long lasting,
• relatively expensive,
• laid in over lapping layers.
80.
81.
82.
83. Tiles – Clay, Concrete
• Glazed and unglazed
• Concrete less expensive than clay roof tile.
• Typically heavy
• Durable
• Highly resistant to fire
• Expensive in first cost
84.
85.
86.
87. Architectural Sheet Metal
Roofing:
• Relatively high in first cost
• Last for many decades.
• Galvanic action should be avoided in the
roof installation.
• Beware of water run-off also re galvanic
action from one metal to another.
94. Lead, Copper: Sheet
• Used since ancient times.
• Self-protecting metal - last many decades.
• Installed in sheets using systems of joining
and fastening
• Maintain water tightness at the seams.
• Seams especially standing & batten seams
create a strong visual pattern.
95. Lead, Copper: Sheet
• Lead oxidizes to a white color.
• Copper turns blue-green in clear air, black
in an industrial atmosphere.
• Chemical treatments and coatings can be
applied to preserve a desired color.