Floor beam span tables of residential structural design we will now look at roof rafter and beam design.
Stick frame roof design.
Let s consider a basic gable wood roof framing design.
Determining the ridge beam height.
The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.
The two basic types of roof construction stick framing and truss assembly both produce a structurally sound roof.
Shed gable hip gambrel and mansard.
It starts with setting ridge and valley beams above the house walls.
Stick framing is building the roof on the construction site one piece or board at a time.
Another common design in the northeast is the saltbox which is a gable roof with one longer side.
Stick framing requires larger lumber and more of it.
Roofs are basically five types.
Continuing on from part 3.
Stick framing can t span very far.
Sometimes the rafter will have a tail and extend out past the wall so that you have a soffit or overhang.
The beam or the ridge is the central part of the structure as all the framing must be connected to it.
Stick roof overview a stick framed roof is made up of individual rafters and that are connected to a top beam.
A stick framed roof uses 2x4 s or 2x6 s or whatever you are framing with but has a ridge board running down the middle ridge line.
Roof framing is one of those carpenter skills that appears quite complicated and indeed some roof designs are difficult.
If you know the slope x in 12 you want to use for your roof framing design you can use it along with the run r to determine the height of the ridge beam for example if the slope is 4 in 12 and the run is 12 feet the ridge beam height m will be 4 feet.
Then dimensional lumber called rafters are cut to fit one piece at a time and shoved up to a framer on the roof that s balancing on scaffolding who installs the rafters.
In this post randy shackelford discusses some design choices available to stick frame builders the challenges they pose and the solutions offered by the simpson strong tie three connector system for stick frame roofing.
Stick framing a roof requires framers to spend much more time on scaffolding ladders and above ground which means more chance for accidents.
Additional boards are placed horizontally on the frames to create a complete cover for the structure.
Here we have a wood framed gable roof.
It is easy for boards to walk off the job site when they are loose and in easy to carry pieces.
You then have rafters running down from this ridge board and resting on the top wall plates.