The Purpose and Pitch of a Roof

Your roof provides your house with valuable functions. Some of those functions are obvious. Others purposes are less obvious but equally important. Here are some of the ways your roof serves your home.

Shade protection

Here in the Phoenix Valley, our sun beats down on our homes in ways that most places never experience. The roof, eaves, and accompanying roof ventilation are the only things standing between us and the ruthless sun rays. Much of the damage your roofing company will see is deterioration caused by sun damage.

Rain diversion


Another purpose of roofing is to divert rain off of and away from the house. The pitch of the roof is what keeps the water rolling off and away from the house. The eaves keep the rain away from the walls, as well. 

Because we have so little rainfall, this is one of the few places in the world where it’s possible to have a flat roof. 

But the protection of our homes and possessions aren’t the only functions of a roof.

Shape of house

The pitch and shape of the roof determine the general silhouette of the structure. Think about it: when you draw the general outline of a home, the roof is what determines what the house looks like from afar. The homeowner who wants an elaborate house design can use other details to make the home stand out but stick to a simple roof.


When adding an addition to an existing home, the roof is the most critical element because it has to blend with the rest of the structure. An addition with a roof that is harmonious with the rest of the structure will look elegant and natural.


When choosing a roof, the shape may be partially determined by pitch. Generally speaking, the lower the pitch, the fewer materials will be required, which will lower the cost of the roof.  

Pitch is partially determined by climate. Imagine having a flat roof during a snowstorm! While a flat roof is ideal for our sunny heat and usually low precipitation, many Valley roofs are pitched because rain can pool on a flat roof. Since we have monsoons, we can get a deluge of water in a relatively short time. When water pools on a flat roof, it causes damage and creates leaks. For this reason, many builders favor a roof which has some pitch to it. 

The pitch of a roof can be determined by measuring how many inches in rises (the vertical) for every 12 inches of horizontal space. The resulting measurement is written as the rise number:12 (for twelve inches). It is written as 3:12 or 5:12 or whatever the pitch happens to be.

Knowing the pitch of the roof is particularly helpful for the construction of an addition or if the homeowner wants to build a shed which will blend seamlessly into the home’s profile.

Patterson Construction Company installs and repairs residential roofs of all kinds, skylights, roof ventilation, fascia and underlayment on Phoenix-area homes. Call 602-825-3638 for a free quote today!