Western Red Cedar Span Tables

Navigating Western Red Cedar Span Tables: A Comprehensive Guide

Western Red Cedar (WRC) is a naturally durable and aesthetically pleasing wood species widely used in outdoor construction projects. Its exceptional resistance to decay and moisture makes it an ideal choice for decks, fences, and other exposed structures. Span tables are essential tools for architects, engineers, and contractors to determine the appropriate spacing between supports when using WRC lumber. These tables provide valuable guidance on load-bearing capacities and help ensure the structural integrity of the project.

WRC span tables typically consider various factors, including lumber grade, species, moisture content, and span length. The grade of lumber refers to its strength and quality, with higher grades indicating better structural performance. The species of WRC, such as Coastal or Interior, can also affect the span table values due to differences in density and strength characteristics. Moisture content is another crucial factor as wet lumber tends to be weaker than seasoned lumber.

To use a WRC span table effectively, it's necessary to determine the correct load category based on the intended use of the structure. Common load categories include live loads (occupants, furniture), dead loads (permanent fixtures, roofing), and snow loads (regional variations). The live load is usually assumed as a uniform distributed load, while the dead load may vary depending on the specific design.

Once the load category is determined, the corresponding span value can be obtained from the table by intersecting the row for the lumber grade and span length with the column for the load category. These values represent the maximum span that the WRC lumber can support without exceeding its allowable bending stress. It's important to note that the span table values are typically conservative and intended to provide a safety margin.

In addition to the span values, WRC span tables may also include deflection limits. Deflection refers to the amount of bending or sagging under a load, which can affect the overall stability and functionality of the structure. The deflection limit is typically expressed as a percentage of the span length and is used to ensure that the structure will not sag excessively under the expected loads.

Using WRC span tables is crucial for ensuring safe and durable construction projects. By carefully considering the load category, lumber grade, and span length, architects, engineers, and contractors can select the appropriate WRC lumber and spacing for their specific design requirements. These tables provide valuable information that helps optimize the performance and longevity of outdoor structures while adhering to building codes and safety standards.