Structure Inspection Section#4 Roof Framing Quiz#5

You should have finished Study Session 4 and Quick Quiz 4 before starting this Study Session. This Study Session covers roof trusses.

The estimated completion time is one hour.

Objectives
At the end of this study session, you should be able to:

• Identify different types of roof trusses.
• Describe the functions of roof trusses.
• Describe the basics of roof truss construction.
• Identify the typical conditions encountered with roof trusses.
• Identify problems encountered with roof trusses.

Give two possible causes of truss sag.

1. Excess load 
2. Overspanning 
3. Weak connections 
4. Cut or damaged webs or chords

On a house that has a truss roof structure, if you see a gap at the top of a partition wall between the wall and the ceiling, what might you suspect?

Truss uplift.

On a roof truss, what is the difference between a chord and a web?

A chord is part of the perimeter of a truss. Webs are the internal members

There are many different kinds of trusses. List as many as you can.

King post, queen post, fink, howe, fan, belgian or doublefink, scissor, mono, pratt, warren, gable end.

What is a common solution for truss uplift?

Attach moldings to ceilings but not walls, and allowing the ceiling drywall to float are common solutions for truss uplift.

Why is it common to find sagging of roof sheathing on trusses?

Trusses are further apart than most rafters. Trusses are often 24 inches on center and some common plywood and waferboard sheathings are not thick enough to span 24 inches without sagging under live load.

Why might a drywall ceiling sag below trusses?

Drywall may sag because ½ inch drywall cannot stand the 24 inches between trusses without sagging, especially if the drywall has been wet as a result of condensation, or during construction and finishing.

Where are notches and holes commonly permitted in trusses?

Notches and holes are not permitted in webs and chords.