ACH 121 Lecture 09 (Roof Frame)

Professor Brandi R. Shepard©
ACH 121-Materials and Methods 1
Professor Brandi R.
Shepard©
Wood Frame Construction
Wood Terms
Framing Methods
Floor, Wall & Roof Systems
Innovations in Wood Frame Construction

Professor Brandi R.
Shepard©
ROOF Framing
Roof Parts/Terms
Roof Shapes/Styles
Framing Conditions
Roof Pitch/Slope

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Parts of the Roof Frame

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FLOOR FRAMING COMPONENTS
 b ea m s a n d g i rd ers
 fl oor joi sts
 su b fl oori n g
Review from last classReview from last class

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 fra m i n g m eth od s
 l a tera l b ra ci n g
 w a l l sh ea th i n g
Review from last classReview from last class
WALL FRAMING COMPONENTS

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Roof Terminology
 GABLE
 Triangular part of the wall
under each end of a roof
gable
rake board

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Roof Terminology
 RIDGE
 Top part of gable or hip
roofs
 Where the roof “folds”
over the top
 Area where rafters meet
ridge board

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Roof Terminology
 VALLEY
 Trough formed by the
intersection of two roof
slopes
 Inside “fold” of two
intersecting roofs
 Comprises of the valley
rafter
 Diagonal rafter that
supports the valley
intersection

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Roof Terminology
 DORMER
 Structure protruding
through the plane of a
sloping roof
 Has its own roof structure
 Small secondary roof
structure in the attic space
 Usually contains a window

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Framing a Roof Opening for a Dormer
• DOUBLE HEADER RAFTERSDOUBLE HEADER RAFTERS
• DOUBLE TRIMMER RAFTERDOUBLE TRIMMER RAFTER

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 RAKE
 Edge of roof along sloping side
Consists of:
 RAKE BOARD
 Edge board under roof structure
following slope
 CORNICE RETURN
 Exterior detail where the wall and roof
overhang meet
 Also known as the LOOKOUT
 Short rafter that runs perpendicular to
rafters, supporting the rake overhang
Roof Terminology

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Roof Terminology
 EAVE
 Flat, horizontal edge at the low side
of a sloping roof
 Gutter placement
Consists of:
 FASCIA BOARD
 Edge board under roof structure
following slope
 SOFFIT
 Undersurface of roof overhang
 SOFFIT VENT
 Opening in soffit under eave to allow
air to flow into attic or area below roof
sheathing

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Eave - Horizontal roof edge
Rake - Sloping roof
edge
Roof Terminology
Eaves & Rakes

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Metal Drip Edge
Soffit
• Wood
• Metal
• Plastic
Gutter
Fascia
Eave Detail

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Rake and Eave Connections

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Detailing
the Abbreviated Eave & Rake Cornice

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Combining Eave and Rake Details
These detailsThese details
describe thedescribe the
various ways avarious ways a
cornice returncornice return
can be finishedcan be finished

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A ladder of lookouts supports and
provides a nailing surface for a
boxed-in rake.
SMALL OVERHANG
LARGE OVERHANG
Soffit Details

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ROOF SHAPES & STYLES
 FLAT
 minimal slope
 ¼” per foot
 SH ED
 slopes in one direction
 slope can vary
These roof types exert NO lateral forces

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 GABLE
 Slopes in two directions
 Rafters meet at top peak to a ridge
board
 H IP
 slopes in four directions
 slope is constant on all sides
These roof styles are most popular in building
construction

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RIDGE CONNECTIONS
Gable RoofGable Roof TerminologyTerminology

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Hip RoofHip Roof TerminologyTerminology

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 GAM BREL
 Like gable, but has two different pitches
 Flattens at top (but does not have a flat top)
 M AN SARD
 Gambrel and hip combined
 Also slopes in four directions
These styles require knee walls and ceiling joists for
structural stability-great for loft spaces

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LEAN-TO ROOF
 SHED MEETING A WALL

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FLAT ROOF OVERHANGFLAT ROOF OVERHANG
CONDITIONSCONDITIONS
Flat roofs are not typical inFlat roofs are not typical in
residential construction in thisresidential construction in this
region primarily due to the weatherregion primarily due to the weather
conditionsconditions (live loads dealing with snow and(live loads dealing with snow and
rain)rain)

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Roof Trusses
• SMALLERMEMBERS
•Uses 2X4’S and 2X6’S
• STRENGTH
Thru Triangulation of members
• MORE COMPLICATEDTO FRAME
COMPLEXROOFS
• LESS EXPENSIVE

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alleys in Trussed Roofs

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Attic Trusses
www.precisionrooftrusses.com/Attic%20Truss.pdf

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ABBREVIATED EAVE
FRAMED WITH
TRUSSES
BOXED-IN TOP CORD
OF TRUSS
EXTENDED TOP CORD
WITH SOFFITED EAVE
Cornice Details using Roof Trusses

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Plywood Roof SHEATHING or DECKING

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SKIP SHEATHING with diagonal bracing
• for use with wood shingles and shakes
Plywood Roof SHEATHING or DECKING

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Plywood Clip:Plywood Clip:
To prevent separation of roof sheathing at midTo prevent separation of roof sheathing at mid
span between rafters or trusses Also allowsspan between rafters or trusses Also allows
moisture expansion of the sheathing; typically 1/8”moisture expansion of the sheathing; typically 1/8”
spacing between panelsspacing between panels

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Roof Slope and Pitch
The angle, or pitch, of a roof is
calculated by the number of inches
it rises vertically for every 12 inches
it extends horizontally.
Also denoted as “rise over run”
For example, a roof that rises 6
inches for every 12 inches of
horizontal run has a 6/12 pitch.

ACH 121 Lecture 09 (Roof Frame)

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ACH 121 Lecture 09 (Roof Frame)

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