NHIE Home Inspection Manual.
Structural Components. Roof &
Ceiling System Questions and
Answers
What are the 3 important functions of rafters & ceiling joists? - answer1) Resist vertical
live & dead load
2) Resist high-wind events
3) Resist seismic events
What is the maximum allowed deflection for rafters with greater than a 3/12 slope? -
answerAnswer:
- L/180
Note
- L is rafter length in inches
- Measure along horizontally (i.e., span) not span
What is the maximum allowed deflection for ceiling joist & low slope roofs (i.e., 2/12 or
less)? - answerAnswer:
- L/240
What are the 4 primary roof styles? - answer1) Gable
2) Hip roof
3) Shed roof
4) Low slope roof
What are the other 2 less common roof styles? (P. 155) - answer1) Gambrel
2) Mansford
What structure is often associated with Gambrel roofs? - answerAnswer:
- Barn
What formula is used to calculate rafter length? - answerAnswer:
- Pythagorean Theorem
- A ²+B²=C²
- A is height from wall plate to right
- B runs from ridge to wall plate
- C is length of rafters
, What is the most common type of roof in North America? - answerAnswer:
- Dimensional lumber (stick framed) roof framing system
What are the 5 main components of a stick framed roof? - answer1) ceiling joists
2) rafters
3) collar ties
4) rafter ties
5) purlins
6) sheathing
For dimensional lumber, what are the 3 factors that impact maximum allowable span? -
answer1) species
2) grade
3) on-center spacing (i.e., 16 o.c., 24 o.c.)
Other than species, grade, & on-center spacing, what impacts the depth (e.g., 2x4 vs.
2x8) of ceiling joists? (P. 156) - answerAnswer:
- How will the attic be used by the homeowner?
- e.g., Will the attic be used for storage or will? If so, the joist depth needs to be
increased.
What three additional factors impact the maximum allowable span of rafters? - answer1)
ground snow load
2) dead load
3) ceiling attachment to rafters
What impacts the dead load imposed on a roof system? - answerAnswer:
- type of roof covering
- e.g., light roof vs. heavy roof covering
Are home inspectors required to determine if structural components are over spanned?
- answerAnswer:
- No
When inspecting a roof & ceiling system, what technique should a home inspector use
to determine if it is correct? - answerAnswer:
- Evidence-base technique
- e.g., inspect for excessive damage, deflection & deformation
How far should ceiling joists lap over a load bearing wall? - answerAnswer:
- 3 in.
What 4 factors determine the amount of fasteners (e.g., nails, etc.) per ceiling joist
connection? - answerAnswer:
1) Roof slope
2) O.c. spacing (e.g., 16 o.c., 24 o.c., etc.)
Structural Components. Roof &
Ceiling System Questions and
Answers
What are the 3 important functions of rafters & ceiling joists? - answer1) Resist vertical
live & dead load
2) Resist high-wind events
3) Resist seismic events
What is the maximum allowed deflection for rafters with greater than a 3/12 slope? -
answerAnswer:
- L/180
Note
- L is rafter length in inches
- Measure along horizontally (i.e., span) not span
What is the maximum allowed deflection for ceiling joist & low slope roofs (i.e., 2/12 or
less)? - answerAnswer:
- L/240
What are the 4 primary roof styles? - answer1) Gable
2) Hip roof
3) Shed roof
4) Low slope roof
What are the other 2 less common roof styles? (P. 155) - answer1) Gambrel
2) Mansford
What structure is often associated with Gambrel roofs? - answerAnswer:
- Barn
What formula is used to calculate rafter length? - answerAnswer:
- Pythagorean Theorem
- A ²+B²=C²
- A is height from wall plate to right
- B runs from ridge to wall plate
- C is length of rafters
, What is the most common type of roof in North America? - answerAnswer:
- Dimensional lumber (stick framed) roof framing system
What are the 5 main components of a stick framed roof? - answer1) ceiling joists
2) rafters
3) collar ties
4) rafter ties
5) purlins
6) sheathing
For dimensional lumber, what are the 3 factors that impact maximum allowable span? -
answer1) species
2) grade
3) on-center spacing (i.e., 16 o.c., 24 o.c.)
Other than species, grade, & on-center spacing, what impacts the depth (e.g., 2x4 vs.
2x8) of ceiling joists? (P. 156) - answerAnswer:
- How will the attic be used by the homeowner?
- e.g., Will the attic be used for storage or will? If so, the joist depth needs to be
increased.
What three additional factors impact the maximum allowable span of rafters? - answer1)
ground snow load
2) dead load
3) ceiling attachment to rafters
What impacts the dead load imposed on a roof system? - answerAnswer:
- type of roof covering
- e.g., light roof vs. heavy roof covering
Are home inspectors required to determine if structural components are over spanned?
- answerAnswer:
- No
When inspecting a roof & ceiling system, what technique should a home inspector use
to determine if it is correct? - answerAnswer:
- Evidence-base technique
- e.g., inspect for excessive damage, deflection & deformation
How far should ceiling joists lap over a load bearing wall? - answerAnswer:
- 3 in.
What 4 factors determine the amount of fasteners (e.g., nails, etc.) per ceiling joist
connection? - answerAnswer:
1) Roof slope
2) O.c. spacing (e.g., 16 o.c., 24 o.c., etc.)
