The run or the base number is 12 inches.
Flat roof trusses section on block.
And ceiling joists in accordance with section r802 8 and for trusses in accordance with section r802 10 3.
They re simple in form and function and are a good example of the modernist principle of clean lines.
Roof truss span chart.
A flat roof truss is also known simply as a flat truss and is not completely flat but rather slightly sloped in order to allow water to run off of the roof.
For seismic design categories a b and c where the distance from the top of the braced wall panel to the top of the rafters or roof trusses above is 91 4.
Just as there are many types of roofs with many roof parts there are many different types of roof trusses this extensive article explains through a series of custom truss diagrams the different truss configurations you can use for various roofs.
While this article focuses on configurations we also have a very cool set of illustrations showcasing the different parts anatomy of roof trusses.
Spaced sheathing or 1x boards may be reduced slightly.
For example a slope of 6 12 means for every 12 inches of horizontal distance the slope of the roof will rise 6 inches vertically.
If you want to build a flat roof then you will need to build a flat roof truss these are designed to span the space between two load bearing walls and take the weight from the roof onto these walls.
Pitch slope the pitch or slope is the incline of the roof expressed as a fraction describing the rise over the run.
The rise will be the elevation change over the 12 inches.
Spans for 2x4 top chord trusses using sheathing other than plywood e g.
Modern architecture has traditionally been characterized by flat roofs flat roofs create long horizontal planes reminiscent of the broad horizon line seen often in nature.