# Construction Math

## Solving Unknown Lengths and Angles # II Dual Pitched Roof

Solving for length's aa and ab

*Solving it Spikey style!!*Before you can find the angles and different lengths you first need to solve for length's aa and ab to find where the roof peak is located in relation to the side walls.

To do that: add the values of both rises from the pitches together.**An example:**

What is Known:

Roof pitch no 1 = 9/12

Roof pitch no 2 = 5/12

length a = 20'

Adding the two rise values together: 9 + 5 = 14

Divide "length a" by this number:

20 / 14 = 1.4285714286, this becomes the multiplier

To solve for "length aa" take the rise of the opposite pitch, pitch #2 = 5 and multiply it with the multiplier:

Length aa = 5 * 1.4285714286 = 7.14285714' = 7' 1 11/16"

To solve for length ab take the rise of the opposite pitch, pitch #1= 9 and multiply it with the multiplier:

length ab = 9 * 1.4285714286 = 12.8571428' = 12' 10 5/16"

##### Construction Math Calculators

#### Area Calculation

#### Arithmetic

#### Estimating / Multiplier

#### Fractions and Decimals

#### How to do things

- Convert Feet in Decimal Format to Foot, Inch and Fraction
- Calculate the Square Footage of a Rectangle Shaped Area
- Equation Manipulation
- Calculating with Percentages

#### Solving a Duel Pitch

- What can you do with the roof pitch?
- Solving for length's aa and ab
- Calculating the Height
- Solving the Angles