Why does roof shape (geometry) matter?
This is a fairly common question we get during home inspections. Especially when we are also doing Wind Mitigation inspections. Roof geometry is very important, especially in Florida, because the different shapes can make a big difference when high wind or hurricane season comes! So let’s talk about the different types of roof shapes and what they mean, and the pros and cons of each.
A gable roof is a pitched roof that basically looks like an “A”. It is sloped on two sides and open at both ends. Some roofing materials typically installed on gable roofs include asphalt shingles, clay/cement tiles and metal. Gable roofs are typically less expensive to replace because they have less surface area. This type of roof is good at shedding water if it has a steep enough pitch. However, it has been known to be susceptible to damage or issues in high wind or hurricane conditions. But don’t worry! Big issues are usually rare. Having a Wind Mitigation inspection is a great way to see if the roof is attached to the home correctly to offset the high wind resistance.
A hip roof is a pitched roof but it doesn’t open on the ends. It looks almost like a pyramid that has a flatter ridge on top. Ever wonder why the Great Pyramids have stood for so long? That shape is extremely strong structurally and highly aerodynamic, which means the wind just passes around it and rarely causes any damage or resistance. Some roofing materials typically installed on hip roofs include asphalt shingles, clay/cement tiles and metal. This is one of the strongest roof shapes. However, replacement of roofing materials can be on the pricier side because the roof surface is greater.
Flat/low slope roof
Flat/low slope roofs are much less common in Florida, but there are some. Some roofing materials typically installed on flat roofs include built up roof, tar and gravel (another form of built up), rolled roofing (like huge flat shingles) and different types of membrane. Flat roofs are convenient because they can be traversed easily, they are usually not as expensive to replace and they are easy to add additional features to if the structure design permits. However, they do tend to “pond”, which means low spots will form and pooling occurs. This can be especially concerning in Florida where we often have flooding rains. On flat roofs, the system should be very well sealed and at least some slope should be incorporated.
These types of roofs were originally designed for farm sheds and lean-to structures. Sometimes these roofs are also called “skillion” roofs. The shape is like half of a gable roof, just one long slope. They are great for their solar potential if built correctly. Some roofing materials typically installed on shed roofs include asphalt shingles, clay/cement tiles and metal. The downside is that they are highly susceptible to wind damage and offer limited protection in harsh weather conditions.
These roofs are often called “barn roofs”. This type of roof is like a gable roof but there are two different slopes. These types of roofs have great potential if a second story is desired. Some roofing materials typically installed on gambrel roofs include asphalt shingles, clay/cement tiles and metal. These roofs require very consistent maintenance and again can be susceptible to high wind damage.
This type of roof is similar to gambrel roofs with the two different slopes, but is almost always four-sided. These types of roofs are not very common in Florida. They offer the pros, but also the cons of both low pitched roofs and a pitched roofs.
There are many other types of roofs, but these few are the most common found in Florida. Sometimes different roof shapes are combined in one house. If you don’t have one of the stronger roof shapes, don’t worry! There are always ways to make it stronger to survive beautiful and crazy Florida!
I appreciate how you described a hip roof as a pitched roof with no openings at the ends and a shape that resembles a pyramid with a flatter ridge on top. My brother told me the other day that he still hasn’t decided what kind of roofing to place on the residence that is currently being constructed he and his fiance will live in after they get married. I’ll provide him this article as a reference and advice him to only deal with a trustworthy roofing installation business to make sure everything is done correctly.