# Gable Wall Top Plate Length

Calculate the length of the top plate based on the horizontal plate's length and the slope ratio of the roof.

There are different ways to approach this, but in its simplest form calculate the diagonal length using Pythagoras, c = square root (a² + b²)

##### Example calculation:
slope ratio = 5 : 12
bottom plate, length a = 15'-5" = 185"

using the slope factor and length a to calculate the height of leg b
5 ÷ 12 = 0.4166666666667 * 185 = 77.083333

multiplying the decimal by 16 (Fraction Precision)
0.083333 * 16 = 1.3 rounded to 1. the fraction becomes 1/16"
leg b = 77 1/16"
185² + 77 1/16² = 40166.84
square root of 40166.84 = 200.4166

multiplying the decimal by 16
0.4166 * 16 = 6.7 rounded to 7. The fraction becomes 7/16"
Adding them together making leg c, the diagonal plate, 200 7/16"

### Diagonal Plate Length

Slope Ratio :12
Bottom Plate Length ft in n
d
Fraction Precision #

#### Results:

 Diagonal Plate in Inches in Diagonal Plate Length ft in

#### Calculation

1. the slope ratio, inches per foot
2. length of bottom plate
3. largest fraction used in result

#### Results

1. length in inches
2. length of diagonal plate (short to long)

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