If you’re thinking about getting a new roof for your home, you’ve probably heard roofing contractors or other roof professionals refer to “a square in roofing” or “1 roofing square.”

These are actually the same thing and simply refer to a unit of measurement that has a value of 100 square feet. It’s an easy shorthand way to think about the amount required to cover a roof, regardless of which specific substance (e.g. asphalt shingles) is being used.

## Why use this term?

A roofing square is a standardized way of thinking about roofing materials and is understood by everyone in the industry.

The reason why the term is so prevalent is because there are so many types of roofs for residential and commercial buildings. For example, there are flat roofs, gable roofs and mansard roofs, and each has different dimensions.

## Calculations

It’s rare that you will ever need to cover a perfectly square roof, so you will need to do some simple geometry to figure out the amount to buy to cover your roof. It goes without saying that the bigger your roof, the more will be needed to cover it. But how much more?

Let’s take the example of a sloped gable roof, which is what you can expect to find in most residential neighborhoods.

**Here, the geometric equation to calculate the amount of asphalt shingles (or other substance) needed is the following: 2 x A x L, where A is the area of each side of the roof and L is the length. **

Once you have this number, it is possible to calculate the necessary materials to order (in square foot terms).

## Different examples

It’s also important to keep in mind that a single roofing square can be the same for homes with widely varying roof dimensions.

For example, consider a roof that is 10’ by 10’. The total area is 100 square feet. This is the same area as a roof that is 4’ x 25’ or a roof that is 5’ x 20’. In each case, the size is the same.

## The headlap

Just keep in mind: roof tiles will overlap each other in order to prevent any water from leaking through. Thus, there will always be some additional roofing coverage known as the headlap that must be factored into any calculation.

Thus, just because a roof is certain dimensions, it might require some extra covering than just the geometric equations used above. This headlap is a way of protecting the roof.

## Conclusions

As you can see, the roofing square is a very useful way of thinking about the way to cover a roof. It gives a wide range of different people in the roofing industry an easy way to think about the amount of roofing material – such as asphalt shingles (in square foot terms) – required to cover a residential or commercial building roof.

So the next time you hear people using the term, don’t be confused by what might seem to be insider jargon. It’s actually a useful way to calculate supply and cost.