Rafter Span Tables - Use these tables to determine lengths, sizes, and spacing of rafters based on several factors such as species, load, grade, and spacing. Visit the roof framing page for more …

Mar 21, 2025 · Rafter spacing is the horizontal distance between the parallel rafters measured from one rafter’s center to the next one. It helps determine the number of rafters based on the building’s length …

Nov 11, 2025 · Roof rafters form the inclined structural framework of a roof, supporting exterior materials and transferring the load down to the building’s walls. The consistent distance between these parallel …

By entering a few key measurements — the rafter length, roof width, and the number of rafters — the calculator instantly provides the optimal spacing. This helps ensure your roof is both structurally …

Sep 14, 2025 · The distance between roof rafters, known as spacing or on-center spacing, is a fundamental design and construction detail that affects structural integrity, insulation efficiency, …

Jul 20, 2025 · In this article, we’ll dive deep into how to calculate rafter spacing for optimal roof support. We’ll explore the factors influencing spacing decisions, common standards, calculation methods, and …

Oct 18, 2025 · In U.S. residential construction, 16 inches on center (16″ OC) is the most common rafter spacing, balancing structural integrity and material efficiency. Many builders also use 24″ OC when …

Oct 20, 2025 · Rafter spacing can sit at 12, 16, 19.2, or 24 inches apart, depending on board size, wood species, expected loads, and rafter length. A key part of understanding proper roof rafter size is the …

Rafter spacing is the distance between parallel rafters or roof joists. It is measured from the center of one rafter to the center of the next, also known as ‘on-center’, which makes it easier to determine the …

Oct 17, 2023 · Rafter spacing is the distance between the centers of two consecutive parallel rafters. The typical on-center spacing provided in the International Residential Code (IRC) 2021 includes …