To calculate your roof area, simply multiply your roof length by your roof slope height, and multiply this by two. This should give you the total area of your roof, not accounting for a chimney or other sections of your roof not covered by tiles.
Things You Will Need
- Square footage of your house
- Pitch of your roof
- Calculator
- Paper and Pen
Tip
This calculation will give a solid estimate for a single slope roof and a simple gable roof with a single pitch...
Step 1: Sketch Roof Outline
Sketch the roof outline using ground measurements as shown in Figure 1 below...
Step 2: Fill in Roof Details
Measure and sketch out dormers, hips, valleys, diagonal distances...
Step 3: Determine Roof Pitch
Pitch refers to the angle of the roof...
Therefore X equals 8 and the pitch is 8/12.
A Note About Pythagorean Theorem
If you know the measurement of two sides... Pythagorean Theorem tells us that the gable (diagonal) length is 7.21’ or about 7’ 3”.
Roof Pitches in Degrees
Step 4: Calculate The Simple Roof Areas
On a simple hip or gable roof, multiplying the eave to ridge length by eave length will give the area...
Step 5: Calculate The Complex Roof Areas
Most roofs in Canada would be considered on the complex side... Multiply L x W to calculate the area for each rectangular section...
Step 6: Measuring or Calculating Gable and Hip Lengths
The slope factor is also used to determine gable lengths... Record all your calculations as seen in Figure 5 below.
