How to Calculate Roof Area

Before you begin work on any roofing project, it’s vital to have an accurate measurement of your roof area. This will allow you to work out everything from how many roof tiles you need to project cost and timeframe for completion. Thankfully, calculating your roof area is a quick and easy process once you know how. In fact, for the classic gable roof that most British homes have, you can work out the size of your roof with just two measurements.

Calculating Your Roof Area: Gable Roof

You’ll first need to measure the length of your roof. This is the length of your roof’s ridge from end to end. Next, you’ll need to measure your roof’s slope height. This is the length from the eaves up to the ridge, NOT the distance between your roof deck and the apex (also known as the run).

If you don’t know these measurements, you can often find them on the building plans from when you bought the property. If you don’t have these, get in touch with your local council, who should be able to provide your property’s building plans.

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.

(Roof Length x Roof Slope Height) x 2 = Roof Area

An Example

Let’s say we have a typical British home with a gable roof. The roof slope height is 7m, with a 9m roof length and a pitch of 45 degrees. Therefore, using our above calculation:

(7m x 9m) x 2 = 126m2

On top of this, we’d also add around 10% excess to account for damages. Therefore, you should purchase enough roof tiles and other materials to cover a roof area of 138.6m2.

Calculating the Area of Complex Roofs

If your roof is not the classic ‘Gable’ shape, or if it has multiple sections such as hips and valleys, we’d recommend splitting the roof into each section and working out the areas individually. If you’re unsure of how to do this, get in touch with a roofing professional. Learn how to find a good roofer.

Or, alternatively – get in touch with us! Our customer service team will be able to help you calculate your roof area, and anything else you might need for your project. Call them on 01295 565 565, email [email protected], or use the handy live chat below.