Low Slope Roof Truss Design

Design solutions for building code permitted low slope applications that cause ponding water.

Low slope roof truss design.

If the truss is long enough you might gain enough height to have a room. Gambrel roofs are the traditional barn style roof. Residential low slope roofing can generally be divided up into two broad categories. Typically the upper chords have different lengths in this particular type of truss that make the apex off center.

Low pitch large span and high wind speeds and this is where you ll find a truss working the hardest. These are attached to the horizontal beam thus making up the triangle s base. The run or the base number is 12 inches. I design trusses for many roofs around nz that have these characteristics your typical 5 degree longrun roof spanning.

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. The answer is maybe. The space is not high enough to stand in but you can crawl around on your hands and knees to retrieve your stored items. Building offsets are common and create intersecting planes that contribute to drainage issues for low slope applications.

Coffman p e secb and thomas g. Pitch slope the pitch or slope is the incline of the roof expressed as a fraction describing the rise over the run. There are three factors that most affect the strength of low pitch trusses. Larger flat roofed applications low slope such as residential condominium complexes row homes and town houses and smaller applications such as residential porch and garage transitions from the main home where the slope of the roof changes dramatically.

Finding the right products for your low slope roof. A low slope roof design typically has a pitch of between 2 12 and 4 12. Can a low slope roof have an attic truss. Specifically the code text typically reads.

Combine these three at their most extreme i e. While this article focuses on configurations we also have a very cool set of illustrations showcasing the different parts anatomy of roof trusses. 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. Most low slope roofs can create a smaller rectangle in the truss that s used for storage.

The upper slope is low pitched and the lower slope is high pitched. The picture makes it easier to understand than to explain. Pitch span and wind speed. Chapter 15 in the 2015 2018 international building code ibc contains installation guidelines that permit a design slope of 1 4 in 12 for certain types of roof covers.

Design professionals frequently specify the minimum code permitted slope with little if any consideration of the resultant valley slope created by the intersecting planes figure 1 ponding water is commonly observed at valley intersections for low slope roof and deck. The style consists of 2 sides with a ridge at the peak just like gable but each side actually consists of 2 different pitches.