In addition, rafter sizing is expressed as a ratio of the roof’s rise to the run (half of the distance) or a fraction of the rise over the run.ĭepending on your roof’s structure and overall size, the sizes of lumber you need for your roof rafters will vary. The roof rafter span is commonly measured by the distance of the rafter projection horizontally from the ridge to the supporting outside wall plate’s outer edge. In general, rafter sizing refers to the thickness and depth range of the specific lumber used for the roof rafter project. Related: Complete Guide to Setting Up Roof Trusses You may decrease the rafter beam space but never increase the rafter beam spacing. In general, a rafter beam spacing should be no more than 16″ apart from another rafter beam. Rafter beams are exposed horizontal structural elements you see in the ceiling designed to support the weight of the building’s roof, transferring the load to a vertical structural part. In general, constructions often use the 4ft to 12 ft rafter spacing for a pole barn. It typically depends on the specifications of the building and the preference of the owner. There is no standard measurement used in rafter spacing for a pole barn. The deflections range from L/∆=180 and L/∆=240. Live and snow loads range from 10 to 70psf (per sq ft), with dead loads ranging from 10 to 20psf. Roof joist spacing has requirements or factors, including the rafter size, rafter span, thickness, wood species, grade, thickness, wind and snow loads, deflection, and location. Roofing joists also join the building’s opposite walls to support the floor above and the ceiling by transferring the roof’s weight to the vertical columns and into the foundation. Roof Joist Spacing GuideĪ roofing joist is a parallel horizontal member or beam that runs across an open space, which can either be laid pitched or flat, exposed or concealed, depending on the construction. In addition, the standard roof rafter spacings commonly used for most building structures are 16″ and 24″. However, the structural engineer may determine other roof rafter spacing measurements, and these may vary depending on the contributing factors affecting it. The International Residential Building Code (IRC), which is the basis of most North America’s building coide, identifies these standard industry measurements. The standard roof rafter spacings measured on-center are 12″, 16″, 19.2″, and 24″. Rafter Spacing Chart Source: lincoln.ne.gov What Is The Standard Roof Rafter Spacing? Still, it’s best to follow the guidelines provided by the Building Code or a Structural Engineer to prevent unnecessary calculation errors and ensure a local Building Department approves it. Remember that using this rafter spacing calculator may provide an accurate estimate.
Once you tear some decking off you can see what you have and how far to tear off. Some times the rafter tails your seeing have been added on years after the building was built. Keep in mind the new rafter tails need to go past the exterior wall about 3 feet so they do not sag later. You might need to remove the roof decking a bit further to make splicing the new rafter tails into the existing rafters. I have done this more than a few times and the prepainting saves a tremendous amount of effort. Touch them up with a final coat after their installed.
Might as well paint the new decking boards also. Only think i can think to add is that it would be a good idea to set up some saw horses to lay the new boards on and paint the new 2圆 curly end boards on ALL the sides BEFORE you install them.