ROOFING SYSTEMS

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ROOFING SYSTEMS
ROOFING SYSTEMS
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ROOFING SYSTEMS
The accepted industry standard for roofing
systems is the NRCA NATIONAL ROOFING COUNCIL of
AMERICA
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ROOFING SYSTEMS
NRCA ROOF CATAGORIES

• Steep slope roofing systems (greater than 312,
  such as tiles or shingles) are generally designed
  to shed water quickly by gravity and are not
  necessarily watertight.
• Low slope roofing systems (not more than 312),
  while also designed to shed (or drain) water,
  must be essentially water impermeable since the
  roof slope is low and will take a longer period
  of time to drain.

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ROOFING SYSTEMS

• Steep slope roofing systems examples are metal
  roofing (standing seam, flat seam, batten seam,
  Bermuda style, various metal shingles), tile
  roofing (concrete or clay), slate roofing
  (natural or synthetic), wood or asphalt shingles.
  
• Low slope roofing systems generally fall into
  two categories built-up roofing and single ply
  roofing, there are also a few low slope metal
  roofing systems.

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ROOFING SYSTEMS

• Built-up roofing systems are just as they imply
  built-up. A series of overlapping sheets of
  roofing felts are imbedded in a asphaltic or
  coal tar hot liquid known as bitumen. The new age
  built-up roof utilizes two overlapping layers of
  modified bitumen. These systems all require some
  type of covering to protect them from UV
  degradation. The typical types are aggregate or
  smooth surfaces.
• Single ply roofing systems are also just as they
  imply a single ply of material. The critical
  issue with single ply roofs is how are they held
  down? Three typical ways ballasted, mechanically
  attached, and adhered.

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ROOFING SYSTEMS
ROOF MEMBRANES AND COVERINGS
Low slope roof systems generally use roof
membranes, which are intended to serve as water
impermeable coverings. They can be divided into
six general categories.

• Built-up
• Polymer Modified Bitumen
• Thermoset (EPDM)
• Thermoplastic (PVC, TPO)
• Sprayed Polyurethane Foam
• Metal

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ROOFING SYSTEMS
SLOPE AND DRAINAGE
NRCA recommends that all roofs be designed and
built to ensure positive drainage. Ponding water
can be detrimental to roof systems and can result
in the following

• Deterioration of the roof surfacing and membrane
  
• Debris accumulation, vegetation and fungal
  growth
• More than desirable deck deflections
• Ice formation and resulting membrane degradation
  or damage
• Difficulties in repair should leaks occur
• Water entry into the building
• Voiding of the manufacturers warranties

Most roofing manufacturers base warranties on a
requirement that limits the time period water can
pond on the roof to 48 hours maximum. The best
way to ensure this requirement can be met is to
provide primary roof slopes at 1/4 per foot.
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ROOFING SYSTEMS
SLOPE AND DRAINAGE

• Coordinate with structural engineers early in the
  project about
• The required degree of slope to maintain
  positive drainage and avoid ponding.
• The means to accomplish the slope (sloped
  structure or flat structure with tapered
  insulation or a combination).
• NOTE If future expansion is anticipated, sloping
  the structure may not be an option.

• Anticipated roof loading.
• Locations of equipment that may enhance
  deflection and create ponding.

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ROOFING SYSTEMS
SLOPE AND DRAINAGE

• Primary roof drainage should be arranged
• When possible, drains should be located at
  mid-span of roof structural supports.
• NOTE Mid-span location will NOT work on a roof
  where structural joists, beams, or tees have a
  chamber.

• Roof will slope towards or away from the roof
  edge.
• 1 drain per every 2500sf - 3000sf max. of roof
  area.
• Try to keep the roof area serving a particular
  drain to a square or rectangular shape.
• How will secondary or overflow roof drainage
  occur (overflow drains or scuppers)?
• Crickets and Saddles sloped at 1/4 per foot are
  used in valleys and to maintain positive slope
  around roof mounted equipment and around
  penetrations.

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ROOFING SYSTEMS
EXPANSION JOINTS
Roof expansion joints are used to minimize the
effects of stresses and movements of building
components and to prevent these stresses from
splitting, buckling/ ridging, or damaging the
roof system. Expansion joints must be placed in
the same location as the buildings structural
expansion joints. In designing the placement of
roof expansion joints, one must consider the
following

• Thermal movement characteristics of the building.
  
• The structural supports and roof deck.
• The roof system selected.
• The climactic conditions to be encountered.
• Where expansion or contraction joints are
  located at in the structural assembly.
• Where steel framing, structural steel, or
  decking change directions.
• Where separate wings of L, U, T, or
  similar configurations exist.
• Where the type of decking changes
• Whenever additions are connected to an existing
  building.
• At junctions where interior heating conditions
  change.
• Wherever differential movement between vertical
  walls and roof deck may occur.

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ROOFING SYSTEMS
AREA DIVIDERS
Where expansion joints are not provided, or the
distance between expansion joints is excessive,
area dividers may help control thermal stresses
in a roof system. Area dividers minimize the
transmission of stress from one area of the roof
to another by dividing the roof into more
uniform and or rectangular areas. Depending on
climactic conditions and regional practices, area
dividers for attached membrane systems are
generally required at 150 to 200 foot intervals.
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ROOFING SYSTEMS
WOOD NAILERS
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ROOFING SYSTEMS
WOOD NAILERS
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ROOFING SYSTEMS
WOOD NAILERS
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ROOFING SYSTEMS
FLASHING
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ROOFING SYSTEMS
FLASHING
Refers to the thin, impervious materials used to
prevent water from entering the roof membrane at
the following points

• Roof Terminations (parapets, roof edges,
  hatches, skylights, equipment curbs, etc.)
• Roof Membrane Joints (roof expansion joints,
  roof area dividers)
• Roof Membrane Penetrations (vent pipes,
  equipment supports, etc.)

There are two basic types of flashing

• Metal Flashing
• Membrane Flashing

NOTE Typically, most roof flashings are
fabricated on site according to the architects
flashing details for that specific situation.
However, many companies now offer prefabricated
flashing components, or alternate methods and
materials. Extreme care should be taken in
reviewing these potential changes, to ensure that
the original waterproofing intent of the flashing
detail is met, and water will not enter the roof
membrane.
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ROOFING SYSTEMS
FLASHING
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ROOFING SYSTEMS
COUNTER FLASHING
Most flashing has associated counter flashing.
Counter flashing serves to shed water over, or
away from, the primary (base) flashing. Points to
remember about counter flashing are

• Counter flashing should be detailed to be
  removable for maintenance reasons.
• In high wind areas, clips to hold the counter
  flashing in place should be used.
• In many situations, flashing and counter
  flashing are vulnerable to the differential
  movement of the components being flashed. In
  these situations, care must be taken to detail so
  that movement can be accommodated without
  compromising the the ability of the flashing to
  prevent water entry.

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ROOFING SYSTEMS
FLASHING
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ROOFING SYSTEMS
WALKWAYS / WALKBOARDS
To protect the roof membrane from foot traffic,
roof walkways or protection course should be
provided in the paths of expected traffic to roof
elements such as mechanical equipment, exterior
building maintenance supports (davits, tiebacks),
roof stairs, access hatches, etc., as well as
around the roof perimeter. The walkway
protection course should be made from durable
materials, made on the job, or manufactured, held
in place by gravity, by adhering to the membrane,
or by mechanical fastenings. Care must be taken
that the layout does not impede the roof
drainage. Each panel (except those that are fully
adhered) should be small enough to be lifted for
roof maintenance if necessary.

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ROOFING SYSTEMS
DECK AND STRUCTURAL CRITERA

• Live Loads, such as such as moving installation
  and maintenance equipment, workers, stored
  materials, wind snow, ice, rain, etc.
• Dead Loads, such as mechanical equipment above
  and below the deck (ducting, piping, conduit,
  sprinkler lines, lighting, etc.) the deck itself,
  sheathing underlayment, roof membrane,
  insulation, and ballast.
• Deck Strength, (gauge, density, type, and
  thickness)
• Drainage
• Placement of expansion joints and area dividers.
  
• Curb and penetration members and details.
• Attachment and securement provisions for the
  deck.

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ROOFING SYSTEMS
INSULATION
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ROOFING SYSTEMS
ROOF INSULATION

• Polyisocyanurate
• Extruded Polystyrene
• Molded Bead or Expanded Polystyrene
• Perlite
• Cellular Glass
• Glass Fiber Fiberglass
• Mineral Fiber
• Composite
• Lightweight Insulating Concrete
• Cellulose Fiber
• Polyurethane

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ROOFING SYSTEMS
ROOF INSULATION

• Able to withstand hot bitumen application
  temperatures required for insulation of a
  hot-applied bituminous roof system.
• Compatible with membrane slice washes,
  adhesives, and other components to which it may
  be exposed.
• Good physical characteristics (high compressive
  strength, rigidity, density, impact resistance,
  etc.) on all surfaces.
• Incombustible, and would meet applicable fire
  codes, and insurance and building requirements.
• Constructed of materials that resist
  deterioration, and inhibit degradation of
  adjacent components.
• Moisture resistant and dimensionally stable
  under varying temperatures and humidity.
• Low K-value (thermal conductivity) so that the
  highest possible R-value (thermal resistance) can
  be obtained in the thinnest dimensions.
• K-value will remain relatively constant over
  time.
• Surfaces accommodate secure attachment to the
  substrate.
• High dimensional stability.

NOTE All roof insulation should be protected
from the elements and construction traffic
before, during, and after installation.
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ROOFING SYSTEMS
INSULATION
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ROOFING SYSTEMS
INSULATION
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ROOFING SYSTEMS
DRAINS
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ROOFING SYSTEMS
DRAINS
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ROOFING SYSTEMS
DRAINS
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ROOFING SYSTEMS
DRAINS
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ROOFING SYSTEMS
DRAINS
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ROOFING SYSTEMS
SCUPPERS
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ROOFING SYSTEMS
SCUPPERS
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ROOFING SYSTEMS
SCUPPERS
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ROOFING SYSTEMS
WINDOW WASHING
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ROOFING SYSTEMS
WINDOW WASHING
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ROOFING SYSTEMS
WINDOW WASHING
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ROOFING SYSTEMS
PENETRATIONS
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ROOFING SYSTEMS
PENETRATIONS
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ROOFING SYSTEMS
SINGLE PLY
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ROOFING SYSTEMS
SINGLE PLY
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ROOFING SYSTEMS
BUILT-UP
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ROOFING SYSTEMS
BUILT-UP
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ROOFING SYSTEMS
BUILT-UP
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ROOFING SYSTEMS
METAL
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ROOFING SYSTEMS
METAL
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ROOFING SYSTEMS
METAL