A gable roof slopes inward on two sides, and the other two sides have a wall with a triangle shape at the top; whereas, a hip roof slopes in on all four sides. The photo above shows intersecting gable and hip roofs: the hip roof is in the back on the main part of the house, and gable roof at the protruding garage.
And here they are again below, represented in diagrams along with other popular roof styles. Hip roofs are more complicated and labor-intensive to build, but are also more wind-resistant in a storm. Gable roofs are easier and less expensive to build, but the triangle-shaped “gable end” is prone to collapse in a hurricane force wind if not properly braced, with a domino-effect knocking down a row of roof framing members once the gable end collapses.
Because hip roofs have been proven in wind tunnel tests to be significantly more hurricane-resistant than gable roofs, there is a windstorm insurance discount for homeowners in Florida that have a roof shape that is at least 90% hip. The calculation is made by measuring the length of the perimeter (edge at fascia) of the roof that is a hip shape as a proportion of the total perimeter. The big gable end at the garage door in the home above would disqualify it for the hip roof discount.
As you might expect with an insurance industry calculation, there are several complicating factors. A gable roof that covers an open entry area, and a porch roof that is attached to the main structure only at the fascia and is not over an enclosed living space, are both not considered as deductions in the calculation of hip perimeter length. Also, a very low-slope or flat roof that is more than 10% of the total roof area over the living space of the home overrides all the other calculations and eliminates the discount.
While engineers and insurance companies evaluate these two most common roof structures based on strength and cost parameters, architects see the two types of roofs as part of their design vocabulary, and it is currently popular to have the main mass of the house topped with a hip roof, with smaller gables added as a kind of embellishment for entry porches, dormers, and garages.
The roof shape is just one element in what your insurance agent calls a “wind letter” or “wind mitigation form,” but is officially known as the “Uniform Mitigation Verification Inspection Form.” To find out more about the form, go to our blog: What is a wind mitigation form for homeowner's insurance?
If you have had a windstorm mitigation inspection and did not get the discounts you were expecting, see our blog post: Why did I get no discounts or only a small discount from my wind mitigation inspection?
You can discover more ways to reduce your homeowner’s insurance premium at our blog: How can I lower my homeowners insurance cost?
To learn about the average lifespan of different roof materials, check out our blog: What’s the average lifespan of a roof?
To recognize when it’s time to replace your roof, go to our blog: How can I tell if the house needs a new roof?
If you want to understand the difference between an “architectural” and a regular shingle roof, see our blog: What's the difference between an "architectural" and a regular shingle roof?
To figure out why your roof is leaking, go to our blog: Why is my roof leaking?
If you can find the answer to any of the above questions, contact either Van or Bill at SitePro 850-934-6800