How to Tie a Roof Saddle to a Rafter: A Comprehensive Guide

When it comes to building or repairing a roof, one crucial aspect is ensuring that the rafters are properly secured to each other and to the rest of the structure. This is where rafter ties come in - horizontal framing members that resist the outward thrust at the bottom of the rafters and effectively 'tie' them into their proper triangular shape.

According to Table R802.5.1(9) of the International Residential Code (IRC), ceiling joists and rafters should be nailed together in accordance with specific guidelines. Additionally, Section R602.3(1) specifies that the rafter should be nailed to the top wall plate in accordance with a particular table.

In a conventionally framed roof, ceiling joists along the bottom of the attic space serve as rafter ties, providing support for vertical attic ceiling loads and resisting tension caused by outward thrust at exterior walls. This is evident in Figure 1: Diagram of conventional system with ceiling joists acting as rafter ties.

As defined by the American Wood Council's Wood Frame Construction Manual (WFCM), a rafter tie is a horizontal framing member that extends across the roof span to resist the outward thrust at the bottom of the rafters and effectively 'tie' them into their proper triangular shape. Its function and location are summarized in the following definition: 'A rafter tie is a horizontal framing member that extends across the roof span to resist the outward thrust at the bottom of the rafters and effectively 'tie' the rafters into their proper triangular shape.'

The most common type of residential roof is a simple gable or hip configuration, consisting of a peak (ridge) and sloped sides. When vertically loaded, the ridge tends to deflect downward, and the bottom of the rafters tends to push outward, making it essential to have a rafter tie in place.

Code references throughout this discussion come from the 2015 edition of the International Residential Code (IRC), which is widely adopted across the United States. In Part 2 of this series, we will discuss the difference between rafter ties and collar ties, two often-confused components that serve distinct purposes.

In conclusion, tying a roof saddle to a rafter is a critical aspect of residential roof framing, and failure to do so can lead to errors in design and construction, resulting in property damage, liability claims, and litigation. By understanding the importance of rafter ties and how they function, homeowners and builders can ensure that their roofs are structurally sound and safe.

Tieing a roof saddle to a rafter