Understanding Collar Ties
Roof framing has gotten complicated with all the tie placement requirements, sizing calculations, and structural considerations flying around. As someone who has framed roofs of every span, I learned everything there is to know about collar ties. Today, I will share it all with you.
What Collar Ties Do
Probably should have led with this section, honestly—collar ties are horizontal members joining opposing rafters in the upper third of the roof. They prevent rafters from spreading apart under load.
Purpose and Function
That’s what makes proper collar tie installation endearing to us roof framers—they provide essential structural support:
- Prevent rafter spread under roof loads
- Add rigidity to roof structure
- Help maintain roof shape during wind and snow loads
Placement
- Install in upper third of rafter span
- Typically placed every 4 feet along roof
- Must be securely fastened to both rafters
Sizing
- Minimum 1×4 or 1×6 lumber for most applications
- Larger sizes for longer spans or higher loads
- Consult local codes for specific requirements
Collar Ties vs. Rafter Ties
Collar ties in upper third prevent rafter spread. Rafter ties (ceiling joists) at plate level resist outward thrust. Both serve different but complementary structural functions.
Installation
- Mark collar tie locations on opposing rafters
- Cut ties to proper length
- Secure with nails or structural screws
- Ensure level and properly aligned
Code Requirements
Building codes specify spacing, sizing, and fastening requirements. Check local codes before construction. Proper installation ensures structural integrity and code compliance.
