Building Roofs In The Round: How Building Trusses Fit Into These Roofs

Building trusses are essential for any roof that is not flat. You cannot build any sloping roof without trusses. Ergo, you might be wondering how round roofs are constructed, and how trusses even fit into these roofs. Here is how.

Round Roofs Are Not Truly Round

Strange, but true; round roofs are not actually round. They are optical illusions. They are actually more like flattened pyramids. When there are six to eight roofing panels or sides, then the roofs look even more round, even though they are not. This is the first step in understanding how "round" roofs are created.

Mono and Mono Scissors Trusses

In most cases, the appearance of round roofs, particularly those that come to a point, are created using a sort of half-truss. Instead of a full up-down truss that creates a point with two sloped sides, these mono truss types only rise to a point. They do not slope back down.

Several of these trusses installed in a circle and covered with roofing material creates the appearance of a round roof, even though the roof is supported by several scalene triangle-shaped trusses. If the contractor does not have the upper points of all of these trusses meet, then no point is formed and the roof looks round and slightly flat. The mono-scissors version elevates the roof significantly more than the mono version.

Custom Trusses

In some instances, a customer can request custom trusses in place of the mono trusses that are typically used. Maybe the client wants to leave the rafters open, or create a cathedral ceiling under the trusses. Whatever the case, the roofing contractor has to consult with a structural engineer to make sure the custom trusses follow building codes while creating the unique features the customer is after.

Really Big "Round" Roofs

When the customer is attempting to build an arena dome, or anything of that particularly large nature, a different sort of approach and truss may be used. In this example, the bow barrel truss is the only option for the job. It  is the only truss that is able to span great distances of roof without collapsing or needing extensions. Even then, the roof is not really round or rounded; it is still an optical illusion. If the "round" roof you are after is for a commercial roofing project, then talk to your roofing contractor about using bow barrel trusses.

To learn more, get in touch with a company like Campbell Truss Company Inc.


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