Residential roof trusses, as shown in Figure A, are an engineered configuration of wood members placed to hold the weight of the roof's finishing materials, the internal structure's ceiling and any snow load that may occur.
Disclaimer
The information herein is written as an informative guide to residential wood roof truss construction and to provide an understanding of the basic design criteria of wood trusses. Homeowners and/or contractors must consult with the appropriate professional engineers and/or other relevant individuals, groups and bodies to ensure that the trusses are designed for the specific roof applications, geographic area where they will be located and that they will meet all pertinent building codes.
General information on roof trusses.
Figure A - House design using roof trusses.
Designs 1 - 3
Designs 4 - 7
Designs 8- 11
Designs 12 - 13
There are two primary advantages of roof trusses. The first is that they are factory built making them far less labor intensive than forming and installing a roof support system on site. Secondly, roof trusses can span very large distances without the need for any center support. The primary disadvantage of roof trusses is that the attic space is not easily usable for storage or potential living space. As well, running an attic air duct system can be very difficult, if the roof trusses were not designed for that application.
Roof Truss - Design 1 - 24' span, 2-web, with plywood gussets (Figure 1)
Figure 1 - Roof truss - 24' span, 2-web, with plywood gussets
Detailed information for a 2-web roof truss with a 24' span with plywood gussets.
Roof Truss - Design 2 - 28' span, 2-web, with plywood gussets (Figure 2)
Figure 2 - Roof truss - 28' span, 2-web, with plywood gussets
Detailed information for a 2-web roof truss with a 28' span with plywood gussets
Roof Truss - Design 3 - 30' span, 2-web, with plywood gussets (Figure 3)
Figure 3 - Roof truss - 30' span, 2-web, with plywood gussets
