Roof Rafter Support

Rafter ties resist the forces caused by gravity loads that would otherwise cause the roof to pancake and push out the sidewalls.

Roof rafter support.

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. If you re framing a gable roof on a new house or building a shed or even a doghouse with a gable roof you ll need to cut a number of roof rafters. By upper third here we mean one third of the length of the rafter from ridge to top plate. Usually trusses are put 24 inches apart.

Simpson strong tie offers a diverse line of hangers to handle almost any application with top flange concealed flange and field skewable and slopeable options. Here we have a wood framed gable roof. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

As each truss is put up on top of opposite walls it must be put up straight and supported while the next truss is put up. In large buildings where heavy trusses are used the purlins are continuous members that rest. Ozco 56638 laredo sunset 2 inch hv rafter clip 10 per pack 4 8 out of 5 stars 27 mitek usp structural connectors jl26 face mount joist hanger light capacity 20 gauge g90 galvanizing finish steel 2 x 6 joist dimensional hangers 50 count. Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

In finding this location we do not count the additional length of the rafter that supports the roof eaves overhang or soffit. Joist hangers are designed to provide support underneath joist hangers are designed to provide support underneath the joist rafter or beam to provide a strong a connection. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. To hold them up until the decking of the roof is placed on top a 12 foot 1 inch by 4 inch piece of lumber is used.

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. Purlins purlins are used in roof construction to support corrugated sheet metal if it is used or to support the sheathing of roofs framed with trusses. Rafter ties are required by code unless the house is designed so that the walls or a structural ridge beam carries the full load of the roof. Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter.

Let s consider a basic gable wood roof framing design. The roof rafters provide integral structural support to the roof.