Glencoe: Section 67 Flashcards
Most complicated frame carpentry in a house
Roof framing because of all the angles involved
When does roof framing begin?
After house walls have been framed.
Nominal X” lumber is used for roof framing but Y is increasingly common
Nominal 2” lumber
I-joist
Using an I-joist requires the same basic understanding of X
rafter layout and roof design.
Main purpose of a roof
protect house from weather with minimum maintenance
Two common roof styles:
The other common roof styles:
Gable roof and hip roof
Gabel, hip, low-slope, and shed
Gable roof:
Gable roof has two sloping sides that meet at the top to form a gable at each end.
Gable:
Triangular wall enclosed by the sloping ends of the roof
A gable roof might include dormers.
Dormers:
upright window projections that add light and ventilation to the second floor rooms or the attic
The most common roof type
Gable
Hip roof:
Slopes at the ends of the building as well as the two sides. The slope on all sides results in an even overhang all around the building and gives a low appearance.
In hip roof, why are maintenance needs reduced?
Because there is no siding above the overhang.
This style of roof is very strong and is often found in regions where severe storms are common:
Hip roof
Low-Slope roof:
(float roof) is not perfectly flat. Instead the rafters are laid at a light angle to encourage water drain
Rafter:
an inclined framing member that supports the roof.
Roof Styles: Low slope roof: ----------------- Sheathing and roofing are applied on X. The ceiling material is applied to the Y.
top of the rafters
underside of the rafters
This type of roof is mostly found in dry climates
Low-Slope roof
Shed roof:
(lean-to roof) shed roof slopes in one direction only.
A shed roof is often used for an X
addition to an existing structure. In this case the roof may be attached to the side of structure of to the roof.
Benefit for shed roofs
cost effective
Gambrel roof:
Variation of gable roof. Steep slope on two sides.
A second slope begins partway up and continues to the top.
Gambrel roofs are commonly used in
barns.
Benefits of gambrel roof:
More useable attic space than a typical gable or hip roof. This space can also be used a second floor
Mansard roof:
Variation of hip roof. It has steep slopes on all four sides. Partway up, a shallow second slope is developed and continues to the top where it meets the slopes from the othersides.
Who brought the mansard roof to N.A?
French who settled in Quebec, canada.
Dutch hip roof:
is related to both the gable and the hip roof. Basically, it is a hip roof with a small gable at each end near the top.
How does a dutch hip roof protect the walls from rain
it has even overhang around the entire building.
Framing square short leg:
Long leg:
Tongue
Blade or Body
Roof framing basics:
Parts of a Roof:
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A basic conventional roof consists of:
More complex roof consists of:
rafters, ceiling joists, and a ridge board.
elements such as braces, valley rafters and jack rafters
Roof framing basics: Parts of a Roof: ----------------------------- Rafter: Rafters serve the same purpose in the roof as X
is an inclined member of the roof framework.
joists in the floor or studs in the wall.
Roof framing basics:
Parts of a Roof:
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Rafters are usually spaced X” or Y” apart.
16” or 24”
Roof framing basics:
Parts of a Roof:
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Rafters vary in depth depending on their X
length, the distance they are spaced apart and their slope.
Roof framing basics:
Parts of a Roof:
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Collar tie:
horizontal tie that connects opposite pairs of rafters to help stiffen the roof.
Roof framing basics:
Parts of a Roof:
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Ridge board:
(ridge) is the horizontal piece that connects the upper ends of the rafters. It extends the full length of the house.
Roof framing basics:
Parts of a Roof:
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Rafters often extend beyond the exterior walls to form X that do what?
eaves (overhangs)
protect the sides of the house from sun and water damage.
Roof framing basics:
Parts of a Roof:
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The tail is the portion of the rafter that
extends beyond the wall of the building to form the eave.
Roof framing basics:
Parts of a Roof:
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Unsupported eaves commonly range from X” to Y” in depth. Deeper eaves should be supported by posts.
6” to 24”
Roof framing basics:
Parts of a Roof:
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The types of rafters shown in on page 469 can be used to frame various styles of roof. Not every type of rafter will be needed for each roof:
- Common rafters extend from the X to the Y at 90deg to both
top plate
ridge board
Roof framing basics:
Parts of a Roof:
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- Hip rafters extend X from the Y formed by the top plates to the ridge board.
diagonally
corner
Roof framing basics:
Parts of a Roof:
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- Valley rafters extend X from the X to the X along lines where two roofs intersect.
diagonally
top plates
ridge board
Roof framing basics:
Parts of a Roof:
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- Jack rafters, also called jacks, never X
extend the full distance from the top plate to the ridge board.
Roof framing basics:
Parts of a Roof:
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There are three kinds of jack rafters.
Hip jack rafters extend from X
Valley jack rafters extend from Y
Cripple jack rafters extend between Z
the top plate to a hip rafter.
the ridge board to a valley rafter.
a hip rafter and a valley rafter or between two valley rafters.
Roof framing basics:
Calculating Roof Slope:
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The slope of a roof must be calculated before
construction can begin
Roof framing basics:
Calculating Roof Slope:
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The calculation for the slope of the roof depends on several factors such as:
roof’s span, run and rise.
Roof framing basics:
Calculating Roof Slope:
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Span:
The span is the distance between the outer edges of the top plates. It is measured at right angles to the ridge board.
Roof framing basics:
Calculating Roof Slope:
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Total run:
One-half the span (excpet when the slope of the roof is irregular).
Roof framing basics:
Calculating Roof Slope:
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Unit run
set length that is used to figure the slope of rafters.
Roof framing basics:
Calculating Roof Slope:
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The unit run for a rafter that is at a 90deg angle to the ridge (a common rafter) is always x”
12”
Roof framing basics:
Calculating Roof Slope:
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The unit run for a rafter that is at a 45deg angle to the ridge is x”
17”
Roof framing basics:
Calculating Roof Slope:
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The measuring line is an
imaginary line running from the outside wall to the top of the ridge.
Roof framing basics:
Calculating Roof Slope:
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Total rise:
is the vertical distance from the top of the top plate to the upper end of the measuring line.
Roof framing basics:
Calculating Roof Slope:
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Unit rise:
number of inches that a roof rises for every 12” of run (the unit run)
Roof framing basics:
Calculating Roof Slope:
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Slope:
ratio of rise to run
Roof framing basics:
Calculating Roof Slope:
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Pitch:
ratio of rise to span
Roof framing basics:
Calculating Roof Slope:
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Either term can be used to describe the slant of roofs and rafters, but X is the most suited term for roof framing
slope
Roof framing basics:
Calculating Roof Slope:
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The triangular symbol above the roof shows the
slope visualy
Roof framing basics:
Calculating Roof Slope:
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When the slope is written out in words, the unit rise is X. For example a roof may have a unit rise of 6” and a unit run of 12”. This would be written X
is separated from the unit run by a slash mark
6/12
Roof framing basics:
Calculating Roof Slope:
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The slope of a roof can also be written in
degrees.
Roof framing basics:
Calculating Roof Slope:
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Plumb lines and level lines refer to the
direction of a line on a rafter, not to any particular rafter cut.
Roof framing basics:
Calculating Roof Slope:
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plumb line:
Any line that is vertical when the rafter is in its proper position is called a
Roof framing basics:
Calculating Roof Slope:
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level line:
Any line that is horizontal when the rafter is in its proper position
Roof framing basics:
Calculating Roof Slope:
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A framing square is used to
lay out plumb and level lines on a rafter.
Roof framing basics:
Calculating Roof Slope:
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A plumb line is drawn along:
A level line is drawn along the:
Tongue of the square
Body or blade
