Size guide
Working out the size of your roof surface
Breaking it down
First of all, in order to make sure your area is square, measure three metres from the corner out along one of the roof edges. From this point measure four metres across the front edge. If the diagonal line that connects these two points is five metres long then your area is square.
When measuring large roof surfaces, make it easier by breaking it down into smaller sections for example if you have an L shaped roof break the space down into two rectangles, measuring them separately and adding them together at the end.
Measure the first of these rectangles, starting with the width, followed by the length, and repeat the process on the second rectangle. Mark these measurements in your notebook.
Calculating the area
To calculate the area multiply the length by the width, so, for example, we have a roof that's 5 metres in length x 3 metres wide then the totals square metres works out at 15m2.
Once you have finished calculating all the measurements, it’s always a good idea to round up your totals just to make sure you have more than enough materials for the GRP roof you are about to take on.