Single Span Vs Double Span Roof

Maximum rafter spans for a patio roof.

Single span vs double span roof.

In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Gable ridged dual pitched peaked saddle pack saddle saddleback span roof. Roof its classification. The span would be 11 5 3 4.

For heavy roofs or in. Of course single span is conservative. So consider a simple gable roof on a 24 foot wide ranch framed with 2x6 exterior walls and a 1 1 2 ridge. The use of only 1 2 or 3 span conditions for steel decking is a legacy from pre software times.

This is the horizontal distance from the inside surface of the supporting wall to the inside surface of the ridge board. Double span decking uses surface material that is long enough to bridge the gap between two joists hence the term double triple span decking uses surface material that spans three joists. 18 open span doubled or tripled 2x12 s. Metal decking plans call for joists to be 24 inches apart so a double span deck plank is at least 48 inches long and a triple span deck plank is at.

An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry. Single span construction refers to a beam or slab which is simply supported assumed pinned at its ends. The result of joining two or more gabled roof sections together forming a t or l shape for the simplest forms or any number of more complex shapes. But with the continuous joists the center beam.

The result is that you can use smaller sized stock be it conventional lumber or i joists for multiple span continuous joists than with simple single span joists. A multi span element has continuity across any interior supports and can be more efficient with regard to considerations such as bending s. Three spans was considered representative of any additional number of spans say 4 5 6 or more. The single roof is a type of sloping roof.

Single roof is defined as a roof having only a single slope on each side of a central ridge whereas in shed roof it has a single slope but without a central ridge. Rather the span is based on the rafter s horizontal projection. Three spans represents the best most optimistic case. Two spans less conservative.

Ok just to clarify i am talking about doubling or tripling the 2x12 s that span the 18 direction and then hanging single 2x12 s spanning appx. 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. A simple roof design shaped like an inverted v.