1. What is Heel Cut in Birdsmouth Joint?

The heel cut is the vertical depth of the birdsmouth joint cut into a rafter where it meets the wall plate. It works with the seat cut to create a secure connection while maintaining the proper roof pitch.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Seat Cut — Horizontal cut depth (inches)
• Roof Pitch — Angle of roof (degrees)
• tan — Tangent trigonometric function

Explanation: The tangent of the roof pitch angle determines the ratio between the heel cut and seat cut dimensions.

3. Importance of Heel Cut Calculation

Details: Proper heel cut ensures structural integrity of the roof while maintaining the correct pitch. Too deep can weaken the rafter, too shallow won't provide enough bearing surface.

4. Using the Calculator

Tips: Measure seat cut precisely (typically 1/3 of rafter width). Roof pitch can be measured with a speed square or taken from architectural plans.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical seat cut depth?
A: Usually 1/3 of the rafter width (e.g., 1.5" for a 2x6 rafter).

Q2: How does roof pitch affect heel cut?
A: Steeper pitches require deeper heel cuts for the same seat cut dimension.

Q3: Can I use this for any roof pitch?
A: Yes, works for all pitches from flat to very steep (0-90 degrees).

Q4: What if my rafter is a different size?
A: The calculation is independent of rafter size - only depends on seat cut and pitch.

Q5: Should heel cut exceed rafter depth?
A: Never - the cut should leave at least 1/3 of the rafter's full depth intact.