Rafter span calculator install#

Metal roof purlins are the members of a metal panel system that run perpendicular to the panels. All dimensions are in inches (millimeters). * Rafter spacing distance generally applies to metal purlins with a nominal thickness of 0.0187 inches(4.8mm) and a minimum yield strength of 40,000 psi (275kg/sq.cm).

6 inches (152.4mm) on center – For roofs having snow loads in excess of 40psf (18.2kg/sq.m).

4 inches (101.6mm) on center – For roofs having snow loads between 20 and 40 psf (9.1-18.2kg/sq.m).

3 inches (76.2mm) on center – For roofs having snow loads less than 20 pounds per square foot (psf)(9.1kg/sq.m).

Here is a list of recommended rafter spacing distances for metal roof purlins:

However, if the building codes allow it, you can always increase your spacing according to your requirements. Many of the metal purlins are used to hold rafters at specified distances apart.īut where the roof has a very heavy snow load, then it’s advisable that you space the rafters closer than what is normally required by the manufacturer.

Rafter span calculator install#

This type of purlin is customizable and easy to install with either fasteners or adhesives, depending on the material that you choose!Ĭustomized rafter purlins are also incredibly durable and will last for many years without any problems. These metal roof purlins come in many different materials including aluminum or steel and you can get them in a variety of finishes. Customized Rafter Purlins – Finally, if you want something made completely custom for your project then customized rafters could be a great choice. Open purlins are also easy to cut and customize, so you can get the exact size that you need!ģ. These are made of interlocking channels which are easy to install with a hidden clip system! Most people choose these because they offer good strength at an affordable price. Open Metal Rafter Purlins – If you need something that is lighter and easier to transport, then open metal rafter purlins could be the best choice for you. You can even get them galvanized for an extra layer of protection!Ģ. These types of metal purlins and rafters come in either cold-formed steel or aluminum, depending on your needs. This type of purlin is typically installed with a hidden clip and the rafters are welded to it on site, creating one durable unit!

Welded Rafter Purlins – If you want something that is durable and easy-to-install, then welded rafter purlins could be your best choice. Each has their own benefits, but it is important to understand the differences between them when you choose your system!ġ. There are three different types of metal purlins and rafters. Rafter Distance Details The Types Of Metal Roof Purlins & Rafters For very long spans, it is recommended that one end post every 200 feet (60.96m) be fitted with a bearing plate to support the purlins.In case the roof spans over 50 feet(15.24m), then the purlins should be designed in pairs by using a single higher purlin at the center of the span to support two lower purlins spaced 30 inches (762mm) apart.In this case it’s advisable to use additional purlins. If the number of purlins used in a span is more than 5, then the center-to-center spacing should not exceed 30 inches (762mm).Good judgment should be used when spacing metal roof purlins for long spans on light-frame construction. “Metal purlins shall not be more than 30 inches (762mm) on center when supporting steel framing and 38 inches(965.8mm) when carrying sheathing only”. Many building codes and metal roof purlin manufacturers recommend the following: However, this can be customized depending on what you need! The standard distance for most buildings ranges from 12″ up to 24″. In general, the larger and heavier a metal roofing structure is, the more space it needs between rafters or purlins! The spacing of metal roof purlins is another important detail that you need to consider before choosing your system. There are many things to consider when you choose your spacing and distance, and we will go through them in this post! The Spacing Of Metal Roof Purlins One of the main components of this type of system is the purlins and rafters. A metal roofing system is a great choice for any building that needs protection from the elements.