90 Hour Course - Roofing Practice Exam
Questions and Answers Latest Versions
2026 Top Rated
What is the main function of intermediate support/collar tie?
Help prevent purlin sag.
What is the ideal location for an intermediate support/collar tie?
Halfway up the rafters
An inspector should be careful not to confuse saggin sheathing with
rafter sag.
True
What is the difference between a knee wall and a purlin?
Knee walls and purlins both provide midpoint support for rafters. Knee
walls provide their support by transferring the loads down to ceiling
joists and walls or beams below. Purlins act as beams running along the
underside of rafters.
What can cause sagging of the top on a knee wall?
The top plate of a knee wall may sag if it is a single plate and if the studs
are not lined up with the rafters above.
Knee walls are also called dwarf walls, struts, or strongbacks.
True
Purlins are 2X4, or 2X6, typically.
True
The Purlin should be the same size as the ridge.
, False
An inspector can think of purlins as small beams that run under the
midpoint of all rafters.
True
Does a roof truss support long ceiling spans?
Yes
What is the purpose of a roof truss system?
A triangular structure used to support a roof
Which is a member of a truss system?
Web
Name 2 engineered wood products that may replace conventional
joists.
Trusses, Wood l-joists
What are 2 possible joist hanger problems?
Undersized, inadequate nails
How does leger board support joists?
is fastened to the beam near the bottom and the joist rests on the top
of the ledger board.
Roof decking could be a minimum ____ if rafters are 16 inches on
center:
3/8 inch plywood if we assume the rafter are spaced 16 inches on
center.
Questions and Answers Latest Versions
2026 Top Rated
What is the main function of intermediate support/collar tie?
Help prevent purlin sag.
What is the ideal location for an intermediate support/collar tie?
Halfway up the rafters
An inspector should be careful not to confuse saggin sheathing with
rafter sag.
True
What is the difference between a knee wall and a purlin?
Knee walls and purlins both provide midpoint support for rafters. Knee
walls provide their support by transferring the loads down to ceiling
joists and walls or beams below. Purlins act as beams running along the
underside of rafters.
What can cause sagging of the top on a knee wall?
The top plate of a knee wall may sag if it is a single plate and if the studs
are not lined up with the rafters above.
Knee walls are also called dwarf walls, struts, or strongbacks.
True
Purlins are 2X4, or 2X6, typically.
True
The Purlin should be the same size as the ridge.
, False
An inspector can think of purlins as small beams that run under the
midpoint of all rafters.
True
Does a roof truss support long ceiling spans?
Yes
What is the purpose of a roof truss system?
A triangular structure used to support a roof
Which is a member of a truss system?
Web
Name 2 engineered wood products that may replace conventional
joists.
Trusses, Wood l-joists
What are 2 possible joist hanger problems?
Undersized, inadequate nails
How does leger board support joists?
is fastened to the beam near the bottom and the joist rests on the top
of the ledger board.
Roof decking could be a minimum ____ if rafters are 16 inches on
center:
3/8 inch plywood if we assume the rafter are spaced 16 inches on
center.
