arrowline house graphic
Serving Rural and Remote Customers Where Others Won't!

Horsefly Construction

Telephone (250) 412-9634

Arrowline DIY Roof Measurement Guide

Measuring your roof accurately is one the most important parts of your Arrowline Do It Yourself roofing project. It is key to making an accurate estimate of the materials needed.

The area of a roof is calculated by taking the lineal measurements of the roof from point to point wherever there is a break in flow.

The following image is a basic roofing design.

Roof Diagram Image

Click on thumbnails for enlarged versions of diagrams

Roof Map Diagram

Step 1

Draw a map of your roof as it looks from the top. Include all roof penetrations. Roof penetrations include chimneys, sun roofs and ventilation pipes and are any item that sits on or extends through the roof.




Roof Map with Perimeter Measurements

Step 2

Measure the perimeter of your roof.





Roof Map with Ridgeline Measurements

Step 3

Measure the ridge lines.

The distance of the ridge lines are necessary to accurately calculate the surface area. On this roof, measuring the ridge on the main area is not necessary as it's length will be the same as the back wall. While it is not necessary to duplicate measurements, it is good policy to measure if there is any doubt.

The length of the ridge on the smaller hip roof section must be measured. If it is not safe to measure the ridges, estimate from the ground or roof edge as accurately as possible. Remember, the more accurate your measurements are, the more accurate your materials list will be.


calculate slope diagram

Step 4

Calculate the pitch. The slope or pitch of a roof is the distance the roof rises vertically for each horizontal foot. The gable is the easiest place to take the measurement. From the corner edge measure 1 foot inwards. From that point measure the vertical distance to the edge of the roof. Using a square will keep your lines straight and at a right angle.

If your vertical measurement is 4 inches then your slope is 4:12. If your vertical measurement is 8 inches then your slope is 8:12. If your roof has sections with differing pitches, each slope value must be calculated and recorded.

Roof Map showing slope and penetration measurementsStep 5

Measure the area of roofing penetrations. This map has two penetrations, the dormer and the sky light. The slope value on the dormer roof must be included.

Step 6

Email your now completed roofing map to for a DIY Roofing Package quote or to request a full information package.