Roof framing Flashcards
What are ceiling joists?
Ceiling joists are those horizontal members that create the ceiling.
What has these three functions:
- Carry finished ceiling load (drywall)
- Act as a second story floor
- Resists outward thrust of rafters
Ceiling joists
Overlap nailing of rafter and ceiling joist. True or false?
True
Ceiling Joists and/or Rafters may need additional hardware .Long TimberLok screws fasten through _____ into the ____ or _____
Long TimberLok screws fasten through both plates into the rafter or truss
The lack of ceiling joists and other framing such as a structural ridge beam may cause structural deformities to occur over time. True or false?
True
Structural ridging resists what?
Sagging
The Ceiling can be reinforced by what two things?
- Strong Back
2. Backing/blocking
What is strong back and what is backing/blocking?
Strongback - 2x’s nailed to top of the ceiling joists at mid-span, provides stiffness. Used only on long spans.
Backing/Blocking – attachment point for partitions running parallel to ceiling joists, also acts as a nailer for drywall.
What are some common rafter parts/ terms. describe each
Span - building width
Run - one half span; horizontal distance under rafter.
Rise – vertical roof height.
Line Length - rafter length, length of rafter minus tail
Ridge – Framing member the tip of the rafter is fastened to
How to find the unit length? How to find Total unit rise ?
Unit Length = found using Pythagorean Theorem
Square root of (Unit Rise2 + Unit Run2)
Total Rise = in terms of inches.
Found by formula Run x Unit Rise
How is overhang measured? How is projection measured?
Overhang is measured along slope of the tail.
Projection is the run of the tail, measured perpendicular to the house wall.
Seat cut is also known as the bird’s mouth. True or false?
True
Plumb cuts are vertical when installed.
Level cuts are level. True or false?
True
What is the common term for roof steepness,
stated as Unit Rise on Unit Run(
Example if Unit Rise is 10 inches then ______ is stated “10 on 12”.)
The slope
Slope # (unit rise) is always compared to 12. The larger the number, the steeper the slope! True or False?
True
What is a ridge board and why is it often dropped .
Ridge board – member to which the upper ends of the rafters are attached.
Often dropped to allow for better support/ventilation.
Where are end rafters located and what supports rake rafters?
Rake rafter should be supported by lookouts
End rafter, typically is outside the building line.
What are collar ties used for? Should they be 1/4 of the span or greater, about 6’ OC?
Collar Ties
Used to reinforce the rafters near the mid span.
Should be 1/3 of the span or greater, about 4’ OC.
What are gable end studs?
Gable End Studs
Non load bearing studs that enclose the triangular gable end of a building.
When framed properly, they have a common difference in length (CD).
What is a hip roof?
A hip roof is a system where hip and common rafters meet at the ridge
Hip rafter size should be one size larger than the common rafter. True or False?
True
The run of a hip rafter is usually at a ____angle with the ____ ______.
The run of a hip rafter is usually at a 45 angle with the wall plates.
What are trusses designed to do?
Designed to support the roof over wide spans. (up to 100 ft)
What are two advantages of trusses?
Requires less wood than standard framing.
May cost more, but takes less time to install.
Overall expense (materials & labor combined) may be similar to standard framing
No truss member may be cut unless under advisement of an engineer. True or False?
True
Often ______ trusses are ______ in place with a ______.
Trusses are generally framed _________but there are exceptions.
Often larger trusses are lifted in place with a crane.
Trusses are generally framed 24” oc but there are exceptions.
Occasionally entire assemblies, or sections are built on the ground and lifted into place. True or false?
True
The first few truss trusses are most dangerous to install and must be ________.
Remaining trusses are _________.
The first few truss trusses are most dangerous to install and must be well braced.
Remaining trusses are braced to the first set.
T bracing is used to replace what?
Lateral bracing
T brace of l brace must be 90% of the length of the brace web. True or false?
True
Size and strength of truss connectors depend on what?
Size and strength depend on prevailing weather conditions.
What is sheathing?
Long dimension runs perpendicular to the rafter or truss
In sheathing, nails are typically spaced _____on the ends and _____ on intermediate supports.
Nails typically spaced 6” on the ends and 12” on intermediate supports.
Large decorative trusses are often spaced farther apart and require _____
Large decorative trusses are often spaced farther apart and require purlins
Framing with purlins allows for what?
Framing with purlins allows for vertical metal roofing products such as standing seam, or corregated roofs
What are three types of dormers?
Gable, shed, and hipped.
These rafters make up the major portion of the roof, spanning from the ridge-board to the wall. They extend at right angles from the plate to the ridge. They are used as a basis or starting point for all other rafters. What rafter is this?
Common rafters
Hip rafters form what? Hip rafters project out from the___ ____, forming an ____ _____. They usually run at a ___ - ____ angle to the plates.
Hip rafters form an intersection of two roof sections. They project out from the roof plane, forming an outside corner. They usually run at a 45-degree angle to the plates.
What is a shed roof?
The shed roof is a roof that slopes in one direction. It is sometimes referred to as a “lean to”. It is commonly used in addition to existing structures. It is also extensively used on contemporary homes
What is a gamble roof?
A gamble roof is a variation of the hip roof. It has two slopes on each side instead of one. The lower slope is much steeper than the upper slope. It is framed like two separate gable roofs
What is a gable roof?
A gable roof is the most common roof style. Two sloping roof surfaces meet at the top. They form triangular shapes at each end of the building called gables.
What is an intersecting roof?
An intersecting roof is required on buildings that have wings. Where two roofs intersect, valleys are formed. This requires several types of rafters.
What is a butterfly roof?
A butterfly roof is an inverted gable roof. It is used on many modern homes. it resembles two shed roofs with their low ends placed against each other
What is a valley rafter?
Valley rafters also create the intersection of two roof sections but project inward, forming an inside corner. Valley and hip rafters are similar in theory and layout.
What is a level line?
is any line on the rafter that is horizontal when the rafter is in position.
What is bird’s mouth and why is it done?
is the term used to refer to the notch cut in a rafter. This is done to make the rafter sit securely on the wall plate so that it can be adequately fastened.
What supports the fascia and soffit?
A the bottom end of the rafter is the tail or overhand, which extends beyond the building. It supports the fascia and soffit.
The plumb line is called the tail plumb line or the _____ cut.
The tail level line is also referred to as the ______ cut
The plumb line is called the tail plumb line or the fascia cut.
The tail level line is also referred to as the soffit cut
Information found printed on the body of a framing square; used to calculate the lengths of various components of a roof system is found where?
On a Rafter Table
The first and last rafter of a gable roof, usually having a finish or trim applied to it; also called barge or fly rafter; is called what?
Rake Rafter
The amount of slope to a roof expressed as a ration of the total rise to the span refers to the ?
Pitch
Horizontal framing pieces in a cornice, installed to provide fastening to for the soffit are called?
The lookout
Supporting timbers at which rafters may intersect each other in a gambrel roof is called?
Purlin Knee Wall
What is a valley?
The intersection of two roof slopes at interior corners
This roof type is a variation of the hip roof. It has two slopes on each of the four sides. It is framed somewhat like two separate hip roofs. What is it?
Mansard Roof
What is lateral bracing?
Temporary or permanent bracing that runs perpendicular to the braced members.
