Roofing Materials

1
Roofing Materials

• Information related to Chapter 12

2
Roofing Materials

• There are an enormous variety of roofing
  materials, selection is based on price,
  durability, appearance, roof slope
• For pitched roofs
• Asphalt shingles
• Metal
• Wood
• Slate
• Tile

3
Roofing Materials

• For low slope and flat roofs
• Roll roofing
• Membrane
• Built-up

4
Roofing Materials

• Definitions
• Square material necessary to cover 100 sq. ft.
  of roof surface
• Exposure number of inches (cm) of shingle left
  exposed above bottom edge.
• Lap (top,head,side) amount of material from
  shingle that is covered by another shingle
• Coverage number of layers of material that are
  applied

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Roofing Materials

• Asphalt shingles composed of
• Felt or fiberglass substrate, impregnated with
  asphalt
• Mineral surface sprayed on surface
• Adhesive seal-down strips at midpoint.
• Multiple layers in architectural (built-up)
  shingles

6
Roofing Materials

• Shingle must resist abrasion from elements,
  degradation from UV, loss of asphalt due to
  drying (heat), etc
• Shingles carry warranties of 15 to 40 years
  depending on the amount of material used to make
  the shingle. Weight per square varies
  accordingly.

7
Roofing Materials

• Wood shakes and shingles
• Shakes are rough surface (hand split or similar)
  and provide heavy shadow lines
• Shingles are sawn and are used for siding as well
  as roofing
• Cedar shingles are the most common, they are
  expensive and must be treated with fire retardant

8
Roofing Materials

• Slate-
• A very long-lasting roof, and quite expensive.
• Mined on the NY Vermont border
• Roof framing must be reinforced for the weight
• Slate should not be walked on if old
• Can be repaired with clip, normally fastened with
  copper nails in pre-drilled holes

9
Roofing Materials

• Tiles
• Clay and Cement tiles used very commonly in
  warmer climates.
• Roof framing must be reinforced
• Applied with mortar or using nails
• Traditionally applied over purlins, nailed to
  sheathing today

10
Roofing Materials

• Metal roofing
• Recent improvements in paint quality and life
  have brought more painted steel roofs into the
  residential market.
• Cost competitive with asphalt shingles, and
  longer lasting, used commonly for agricultural
  structures
• Attached with gasketed nails or more commonly
  with gasketed screws

11
Roofing Materials

• Roll roofing
• traditionally used for low-slope residential
  work.
• Available in single and double coverage.
• Very inexpensive, but considered unattractive
• Applied with nails and tar, tar typically leaks
  out at edges

12
Roof Framing

• Membrane roofing
• Rubber roofing (EPDM) and other similar
  materials come in sheets or rolls, are glued or
  ballasted to the roof, and seams are heat or
  solvent welded.
• Materials are relatively expensive, but roof is
  long lasting and stays flexible.

13
Roof Framing

• Built-up roofing multiple layers of felt and
  tar applied to a roof deck, and then the surface
  is covered with ballast.
• Labor intensive, nasty materials, and dangerous
  work, but it used to be the only way to get a
  waterproof flat roof

14
Roofing Materials

• Applying a shingle roof
• Sheathing is installed with H clips
• Drip edge installed on eave under underlayment
• Underlayment 15 lb felt is used as initial
  waterproof barrier, and separation between roof
  deck and roofing
• Waterproof underlayment is used for lowest 36 to
  extend inside of eave 24
• Drip edge installed over underlayment on rake edge

15
Roofing Materials

• Starter course is installed with tabs cut off, so
  that adhesive is at eave edge
• First course of shingles are then started at edge
  of roof, and nailed with four or six nails each.
  Always nail below the adhesive strip, and drive
  nail flush

16
Roofing Materials

• Succeeding courses are offset by half a tabs
  width (six step method). Many shingles have a
  notch to assist alignment.
• With architectural shingles, no defined offset is
  necessary, and spacing can be varied.

17
Roofing Materials

• As you work toward the ridge, check your layout
  to keep courses straight, and to adjust last
  courses as necessary.
• Ridge is capped over a vent (typically). Run cap
  shingles opposite prevailing winds. Cut cap
  shingles from triple tabs.

18
Roofing Materials

• Hips Hip roofs are shingled up to the hip cap,
  and then capped
• Valleys are a collection source for water, and
  a common point for leaks. Valleys can be handled
  as opened or closed. Closed valleys can be cut
  or woven

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Roofing Materials

• Valleys Open valleys are used with either
  mineral surface roll roofing or aluminum flashing
  in the valley. Width of watercourse increases
  down the valley. Advantage is the unobstructed
  watercourse, disadvantage is appearance

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Roofing Materials

• Closed valleys Closed valleys are either woven
  or cut.
• Woven valleys require shingles on each roof to be
  laid at the same time. Provide double thickness
  the full valley length. Require the same pitch
  on each roof.

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Roofing Materials

• Cut Valleys Used commonly because they are fast
  and have good appearance. Commonly done with
  architectural shingles (due to thickness). Each
  side is adjusted so that no shingles end within
  12 of valley.

22
Roofing Materials

• Closed valleys variation on the cut valley is
  to use step flashing between each course.

23
Roofing Materials

• Roof Ventilation Natural Convection (hot air
  rising) will move warm moist air out in winter,
  and keep ice dams from forming
• Soffit and ridge must be opened
• When ridge and soffit can not be opened, gable
  end vents, or pan vents can be used

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Proper cornice detail

• If using gable end vents or pan vents, use 1sq ft
  per 300 sq ft of attic space.
• If using ridge vent, allow air to move unimpeded
  from soffit to ridge, keep insulation away from
  underside of sheathing

25
Ice dams

• Keeping the underside of sheathing cold will keep
  the snow from melting, and keep ice dams from
  forming.
• Snow slides, heat tape, calcium chloride, roof
  rakes, etc

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Estimating

• To determine the number of squares of roofing
• Determine the rafter length (including overhang)
  and the fascia length (including overhang)
• Multiply to get area in square feet
• Add additional materials for shingles at gable
  ends, ridge, etc .(typ 10)
• Divide by 100 to determine the of squares
• If you want to work in fractions of a square,
  determine the number of bundles of shingles
• Triple tab Three bundles to the square
• Architectural Four bundles to the square