Broward County HVHZ | Roof Structure

Keep Walls Together: Collar vs Rafter Ties

Roof weight pushes outward on your walls. Without the right ties, walls spread apart and the roof comes down. Collar ties and rafter ties do different jobs. Here is which one you need and why.

Every
Rafter Pair
4'
Max Spacing
0
Lbs Thrust Force
Calculate Tie Requirements Compare Types
Roof Truss Force Demonstration
COLLAR TIE
RAFTER TIE
No Load Applied
Rafters meet at ridge. Walls are plumb and stable.
Comparison

Collar Ties vs Rafter Ties

They look similar but do completely different jobs. Here is what each one does.

Collar Tie

Upper third of roof

  • Located in upper third of rafter span
  • Prevents rafters from separating at ridge
  • Resists uplift forces during high winds
  • Does NOT prevent wall spreading
  • Required every 4 feet maximum
Primary Purpose Ridge Connection

Rafter Tie

At wall plate level

  • Located at or near wall plate level
  • Prevents walls from spreading outward
  • Resists horizontal thrust from roof loads
  • Critical for structural stability
  • Required at every rafter pair
Primary Purpose Stop Wall Spread
Common Questions

Tie Connection FAQs

What is the difference between collar ties and rafter ties?
Rafter ties connect rafters near the wall plate and prevent the roof from pushing walls outward. Collar ties connect rafters in the upper third of the roof and mainly prevent rafters from separating at the ridge. Rafter ties stop spreading, collar ties stop lifting.
Which is more important for hurricane protection?
Rafter ties are more critical for preventing structural failure during hurricanes. The outward thrust from roof loads can push walls apart if not properly resisted. Without rafter ties at the plate line, walls can spread and the roof can collapse.
How often do rafter ties need to be installed?
In Broward County HVHZ, rafter ties are typically required at every rafter pair for roofs with slopes greater than 3:12. The ties must be sized and fastened per engineering calculations based on the span and roof loads.
Can ceiling joists serve as rafter ties?
Yes, ceiling joists can function as rafter ties if they are properly connected to the rafters and run parallel to them. The connection must be able to resist the horizontal thrust. This is the most common configuration in residential construction.
Tie Requirements
Rafter Ties Every pair
Collar Ties 4' max O.C.
Connection 3-10d nails min
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