14

Chapter

Roofing Materials and Methods

Objectives

• List the covering materials commonly used for sloping roofs.
• Define roofing terms.
• Describe how to prepare the roof deck.
• Describe reroofing procedures for both asphalt and wood shingles.

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Objectives (Cont.)

• Demonstrate correct nailing patterns.
• Select appropriate roofing materials for various slopes and conditions.
• Describe the application procedure for a built-up roof.
• Describe the use and application of wood shingles in residential construction.

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Objectives (Cont.)

• Explain how various roofing products are applied.
• Describe the different types of roofing tiles and how they are made.
• Demonstrate the proper positioning of gutters.
• Estimate materials needed for a specific roofing job.

Monier Group

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Roofing Materials

• Protect structure and contents from weather and dust
• Should offer some fire resistance and durability
• Can add color, texture, and pattern to structure

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Types of Materials

• Roofing materials may be
• Asphalt, wood, metal, and mineral fiber shingles
• Slate, tiles (clay or cement), or sheet materials
• Built-up roofs are fabricated on job
• When selecting materials consider
• Initial cost
• Maintenance costs
• Durability
• Appearance

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Roof Pitch

• Manufacturers list minimum slope requirements for asphalt roofing products

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Roofing Terminology

• Square
• Coverage
• Exposure
• Head lap
• Side lap
• Shingle butt

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Preparing Roof Deck

• Roof sheathing should be smooth and securely attached
• Inspect roof deck for nails, holes, sharp edges
• All types of shingles can be applied over solid sheathing
• Skip sheathing is better in some cases
• Attics should be properly ventilated

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Asphalt Roofing Products

• Widely used
• Fall into three groups
• Saturated felts
• Roll roofing
• Shingles
• Architectural shingles have layers to look like wood shingles

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Roof Underlayment

• Consists of thin cover of asphalt-saturated felt
• Protects sheathing
• Prevents entrance of rain and snow
• Prevents contact between shingles and resinous areas in sheathing

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Drip Edge

• Should be applied to roof edges along eaves and rake
• Made from galvanized steel or aluminum
• Causes water to drip free of underlying cornice construction

​

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Ice-and-Water Barrier

• Recommended for buildings in cold climates
• Prevents leak-through from ice dams or wind-blown rain
• Materials are self-sealing around nails and deck joints

​

Owens Corning

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Flashing

• Water-resistant sheet that keeps roof joints watertight
• Materials for flashing
• Zinc-coated metal
• Copper and lead
• Aluminum
• Ice-and-water barrier
• Roll roofing

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Valley Flashing

• Flashing seals valleys against leakage
• Should be smooth
• Should move water quickly and handle backup
• Open valley flashing is laid down before shingling begins

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Woven Valley Flashing

• Method that runs shingles across valleys
• Often used when reroofing
• Only asphalt strip shingles may be applied this way

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Closed-Cut Valley Flashing

• Two intersecting roof surfaces are individually shingled
• Each strip is extended at least 12″ beyond center of valley

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Flashing at Walls

• Metal step flashing
• Applied to waterproof joints
• Should be used where sloping part of roof abuts wall
• Siding serves as cap flashing

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Chimney Flashing

• Has two parts that move independently
• Base flashing is attached to roof
• Cap flashing is attached to chimney
• Cap flashing must go over top of base flashing

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Chimney Saddle

• Auxiliary roof deck on sloping roof
• Diverts water from behind chimney
• Large saddles must be framed
• Small saddles can be formed using pieces of exterior plywood

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Vent Stack and Skylight Flashing

• Lay shingles up to stack, fit last course around it
• Install flange and apply shingles over upper side of flange
• One-piece plastic skylights have one-piece flashing to go under shingles

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Chalk Lines for Shingles

• Snap chalk lines to keep shingles in alignment
• Use lines as reference marks for starting each course
• Space them according to type of shingle and layout pattern

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Fastening Shingles

• If available, use lift to hoist shingles to roof
• Number of nails and correct placement are very important
• Pneumatic-powered nailers are often used to install shingles

Asphalt Roofing Manufacturers Assn.

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Starter Strip

• Backs up first course of shingles
• Covers gap between tabs
• Failure to install will damage underlayment and sheathing

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First and Succeeding Courses

• Start first course with full shingle
• Three-tab shingles cutouts are centered over tabs in course directly below
• Approved nailing pattern is important for appearance and weather protection

Johns Manville

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Hips and Ridges

• Special hip and ridge shingles may be available from manufacturer
• They can be made with three-tab shingles
• Nail hip and ridge shingles 5 1/2″ back from edges

​

Asphalt Roofing Manufacturers Assn.

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Wind Protection

• Adhesive on shingles prevents wind from lifting and damaging tabs
• In high-wind areas, use wind-resistant shingles
• Self-sealing shingles are satisfactory for roofs with slopes up to about 60°
• Interlocking shingles are designed to resist strong winds

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Low-Slope Roofs

• For slopes less than �4-in-12, follow special procedures
• Use two layers of felt underlayment cemented together
• Ice-and-water barrier can also be used

CertainTeed Corp.

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Roll Roofing

• Used as main roof covering, and sometimes as flashing
• In residential construction, double-coverage roll roofing provides good protection
• It is usually applied parallel to eaves
• Ice-and-water barrier can be used as underlayment along eaves

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Parallel Layout

Bird Division, CertainTeed Corp.

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Reroofing

• New shingles can be placed on old roof when
• Strength of existing deck and framing is adequate
• Existing deck is sound and will provide good anchorage for nails
• Building code allows additional layer of shingles
• If removing old roof, clear away all old materials down to sheathing

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Reroofing over Asphalt Shingles

Asphalt Roofing Manufacturer’s Assn.

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Safety Note

• Asbestos poses health hazards
• Removal of asbestos shingles may release asbestos fibers that can be inhaled
• Removing asbestos must be done by certified crews
• If you are uncertain of asbestos content, have samples of material tested

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Built-Up Roofing

• Many flat roofs are covered with built-up roofing
• Hot asphalt and saturated felt layers are laid down
• More hot asphalt is spread over felt underlayment to bind gravel

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Rubber Roofing

• Made from recycled tires
• Installed quicker than other roofing systems
• Rubber roofing membrane is folded back so adhesive can be applied

Johns Manville

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Ridge Vents for Asphalt Roofing

• Venting at eaves, gable ends, and ridge helps dissipate heat and moisture
• Types of vents
• Rolled over ridge opening
• Rigid plastic fastened over vent opening

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Wood Shingles

• Available with or without polymer fire-retardant treatment
• Made from western red cedar, redwood, or cypress
• Best grade is cut so annular rings are perpendicular to surface
• Exposure of wood shingles depends on slope of roof

​

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Sheathing

• Solid sheathing for wood shingles may be 1″ boards, plywood, or OSB
• Open, skip, or spaced sheathing is sometimes used
• Layer of shingle breather may be used to provide airspace

Cedar Shake and Shingle Bureau, Benjamin Obdyke, Inc.

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Underlayment

• Normally not used for wood shingles
• Exception is when applied over solid sheathing
• If roofing felt is used to prevent air infiltration, rosin-sized building paper or dry unsaturated felts are suitable

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Fire Resistance

• Flame-spread and burn-through rates for wood shingles and shakes can be reduced
• Shingles can be pressure-treated with fire retardants
• Flame-penetration time can be increased by using 1/2″, Type X gypsum board under sheathing

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Flashing

• Eaves flashing strip or ice-and-water barrier is required in cold areas
• Use good-quality materials for valleys and eaves flashing
• Tight flashing around chimneys is essential

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Nails

• Use rust-resistant nails with wood shingles
• Shingler’s or lather’s hatchet
• May be used to lay wood shingles
• Has blade for splitting and trimming

Tru Value Hardware, Ashland, WI

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Applying Shingles

• First course of shingles at eaves should be doubled or tripled
• Horizontally space all shingles 1/4″–3/8″ apart
• Use board to line up courses of shingles

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Shingled Hips and Ridges

• Tightly cover ridges and hips to avoid roof leaks
• Nails should not be exposed to weather
• Use shingles of same width as roof exposure
• Factory-assembled hip and ridge units available

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Reroofing with Wood Shingles

• If old wood-shingle roof is good, it need not be removed
• Renail or replace all warped, split, and decayed shingles
• Raise level of valleys by applying wood strips

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Wood Shakes

• Available as
• Straight split
• Hand split and resawn
• Taper split
• Should not be used on roofs with insufficient slope for good drainage
• Proper nailing with rust-resistant nails is important

Cedar Shake and Shingle Bureau

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Roofing Tile

• Commonly made from concrete or clay
• Comes in many colors, textures, and shapes
• Some types are glazed
• Additional framing or bracing may be required to support tile

Monier Group

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Installing Tile Roofing Units

• Requirements for underlayment depend on roof pitch and local climate
• Two plies of 15 lb. felt are recommended
• Battens are installed on roof to hold tiles in place

Monier Group

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Hips, Ridges, and Rakes

• Install nailer boards on edge at hips and ridges
• Set nose ends in bead of roofer’s mastic
• Waterproof joints between field tile and trim tile
• Apply flashing around chimneys, pipes, and vents

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Metal Roofing

• Used on structures where heavy snow occurs
• Snow tends to slide off metal roof
• Sheets heavily coated with zinc galvanizing or aluminum-zinc alloy are approved for permanent structures
• Sheets with lighter coatings of zinc will likely require painting every few years

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Zinc-Aluminum Coated Steel Roofing

• Coating is applied by hot-dip process
• Gage sheets are formed to add ribs to sheets

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Galvanized, Corrugated Roofing

• Sheets are generally 24 or 26 gage
• Heavier gage has added strength
• Zinc coating for durability is important
• Lighter metal can be used
• On temporary buildings
• Where most economical construction is required

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Slope and Laps

• Metal roofing sheets may be laid on slopes as low as 3-in-12 (1/8 pitch)
• Lap sides of corrugated sheets by 1 1/2 corrugations
• Sheet metal roofing that looks like clay tile is available

Met-tile Inc.

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Fasteners

• Self-drilling screws with attached neoprene washers are used to fasten sheets
• Screws should be driven through tops of corrugations or ribs
• Accessories are available for installing metal roofing

American Building Components

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Aluminum Roofing

• Usually makes long-lasting roofs
• Aluminum alloy sheets have corrugation spacing of �1 1/4″ or 2 1/2″
• Installation methods for sheet metal apply to aluminum sheets
• Aluminum sheets should be stored so that air will have free access to all sides

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Shakes and Valley Flashing

• Aluminum shakes are made of aluminum-magnesium alloy
• Available in various colors
• Valley flashing for metal roofs uses ice-and-water barrier and preformed metal flashing
• Use circular saw to cut metal panels for valleys and hips

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Gutters

• Gutters or eaves troughs collect rainwater from edge of roof and carry it to downspouts
• Downspouts direct water away from foundation or into drainage system
• Gutters must be sized to suit roof areas
• Size of downspouts or conductor pipes also depends on roof area

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Metal and Plastic Gutters

• Include various component parts
• Systems can be quickly assembled and installed onsite
• Parts are held with soft pop-rivets or sheet metal screws

Crown Aluminum Industries

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Estimating Roofing Materials

• First calculate total roof surface area to be covered
• Another method is to find total footprint of structure
• Convert ground area to roof area by adding percentage determined by roof slope
• Divide total square feet of roof surface by 100
• Add extra for waste, hips, and valleys

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Determining Roof Slope

• Stand away from gable end
• Frame roof inside of folded carpenter’s rule
• Locate reading point on chart for pitch

Asphalt Roofing Manufacturers Assn.

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Safety Note

• When working on pitched roofs
• Wear shoes with rubber or crepe soles
• Wear safety harnesses with lines tied off
• Wait until surface is dry before working
• Sweep away sawdust, loose debris, and dirt
• Install shingle underlayment as soon as possible
• Install temporary 2 × 4 cleats as toe holds
• Remove unused tools, cords, and other loose items from roof

​

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Construction Careers �Roofer

• Installs roofing material on new buildings
• Repairs or replaces roofs on existing structures
• Works for building contractors or roofing companies
• May learn as helper on jobsite or complete apprenticeship program

Huntstock/Thinkstock

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