Calculating the dimensions of a hip roof may seem daunting, but it’s an essential skill for civil engineers and anyone involved in roofing projects.

In this straightforward guide, we’ll walk you through the steps to calculate your hip roof, ensuring that your roofing project goes smoothly.


A hip roof is a type of roof design where all sides slope downwards towards the walls, usually with a gentle slope. This design not only adds aesthetic appeal but also provides stability and durability to your roofing structure. Let’s dive into how to calculate the key dimensions for your hip roof.

Step 1: Measure the Building

Start by measuring the length and width of the building’s exterior walls. Be sure to include any overhangs, as they will affect your calculations. For simplicity, let’s assume you have a rectangular building with dimensions: Length = 40 feet, Width = 30 feet.

Step 2: Determine the Pitch

The pitch of a roof is the slope or steepness of the roof. To calculate it, you need the rise (vertical height) and the run (horizontal distance). The rise is typically determined by the height of the roof’s ridge.

Example: If your ridge height is 10 feet, the rise is 10 feet.

The run can be found by dividing the width of your building by 2 (since you have two hips).

Example: Run = Width / 2 = 30 feet / 2 = 15 feet.

Now, you can calculate the pitch:

Pitch = Rise / Run

Pitch = 10 feet / 15 feet = 0.67 (or 6:9)

Step 3: Calculate the Hip Length

The hip length is the distance along the hip line where two roof sections meet. You can use the Pythagorean theorem to calculate it. In a right-angled triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.

Hip Length = √(Rise² + Run²)

Using our example:

Hip Length = √(10² + 15²) = √(100 + 225) = √325 = 18.02 feet (approximately)

Step 4: Calculate the Total Hip Roof Area

To find the total roof area, you’ll need to calculate the area of one triangular hip section and then multiply it by four (since you have four hips on a rectangular building).

Area of One Hip Section = (Hip Length x Run) / 2

Total Roof Area = 4 x Area of One Hip Section

Using our example:

Area of One Hip Section = (18.02 feet x 15 feet) / 2 = 135.3 square feet

Total Roof Area = 4 x 135.3 square feet = 541.2 square feet


Calculating your hip roof doesn’t have to be complicated. By measuring your building, determining the pitch, calculating the hip length, and finding the total roof area, you can confidently plan your roofing project. This knowledge is valuable for civil engineers and roofers alike, ensuring that your hip roof not only looks great but also functions efficiently.


As a civil engineer and roofer, I love to share the experience that I have gained through the last couple of years. In the roofing industry, practical experience is a very crucial fact that can help you a lot. Hence, I want to help you with my blog.

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