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Believe it or not, there are many different styles of roofs out there.  Generally, the types are grouped into two categories: flat or sloped, based on their pitch. And even flat roofs can have a slight pitch. From there, there are varying degrees of each. There’s a wee bit of math and science that go into deciding the pitch of a roof – but first let’s chat about why we have sloped roofs at all.


How steep your residential roof slopes, or the pitch, can depend on where you live. For example, our customers in Tennessee have a slightly steeper pitch than a house in Florida. Too flat of a roof would allow snowfall to accumulate, while a steep pitch would cause ice and snow to slide off too quickly.  An architect designs this portion during the build of your home.


Generally speaking, residential roofs have a slope because most homes see some sort of precipitation, no matter their location. A specific angled roof ensures that any precipitation flows off quickly enough not to do any damage to the roofing shingles (no pooling or gathering).

A pitched roof also enables a home to have room for insulation between the attic space and the interior of the home. This helps to regulate the climate of the home as well as promotes energy savings, i.e., running the A/C less because the house is well insulated. A pitched roof is actually about 10-15% more compact than a flatter roof, so with a more limited exterior space, you have higher thermal insulation!

Watershed is not the only area where gravity comes in to play here. Exterior walls are load-bearing walls, meaning they hold the weight. Having a flat roof would center the weight of the roof on the home, whereas a sloped residential roof will ensure that the heavyweight is evenly distributed to all exterior walls. This is very important in areas of snowfall as well. Sitting snow adds a lot of weight to a home’s roof.

Think of a triangle. A triangle is the strongest shape. Do you know why? It’s inherently rigid. We could go into the details of that more, but if you’re truly interested, there’s more information if you Google the Law of Cosines, a generalization of the Pythagorean Theorem (flashbacks to high school math, anyone?).

The Golden Ratio

In residential roofing, professionals use The Golden Ratio. That’s right, the same thing you may have heard of with the Parthenon or maybe the Great Pyramids. It provides some equilibrium and balance to the home’s construction, and many architects use this when designing a build for a home. The ratio, 1:1.61, repeatedly occurs in nature and beyond. When you see a home with a sloped roof, it’s because of this ratio.

Honestly, the short answer to why houses have sloped roofs is easy. The water needs to run off. The long answer can send you down mathematical, historical rabbit holes. So while we won’t get into that here, know that there is a good reason for a sloped residential roof. Little bit esthetics, a lot of bit design and function; a sloped roof does many things for your home. If we’ve piqued your interest on roofing design, head over to one of our latest blogs here, where we talk in detail about different roof designs!