What’s In a Roof?
Mon Aug 20 2018
Your roof says a lot about your house. It can hint at when your home was constructed, the style of the home, and its regional risks. And those details can also tell insurers an important thing: how resistant your home is to wind damage.
Let’s take a look at the details of a roof and what they mean for your home insurance.
Which Roof Shapes Mitigate Wind Damage
The most common roof shapes for homes tend to be:
- Hip. This roof has slopes on all four sides and they come together at the top to form a ridge. They are sturdy roofs that are durable in high-wind areas.
- Gable. This is a peaked, triangular roof that allows for attic space or vaulted ceilings. They can make a roof more susceptible to collapse from high wind damage if they aren’t reinforced adequately.
- Mansard. Also called a French roof, this is a four-sided roof with a double slope on each side that meet to form a low-pitched roof. Because of the low pitch, these aren’t ideal for homes in area that get a lot of snowfall.
- Flat. This is a roof that has nearly no pitch and allows for extra living space, like a rooftop garden. However, they aren’t ideal for homes in areas with heavy rainfall.
- Gambrel. Also called a barn roof, this roof has two different slopes and is often seen on Dutch Colonial and Georgian style homes. The open design of this shape isn’t ideal for homes in high-wind regions.
- Skillion. Also called a shed roof or lean-to, this is a single, sloping roof often used to cover attachments to a home, like a porch. Again, this shape isn’t ideal for homes in hurricane-prone areas.
- Combination. You’ll often see hip roofs with gable roof portions over dormers or a skillion over the porch.
As you might’ve guessed from the description, a hip roof usually nets homeowners a lower premium on their home insurance, especially if they live in high-wind areas. This shape better mitigates wind damage.
However, the material the roof is made of and the way it’s attached to the home also play a key role in the longevity of the roof and the amount of wind damage a home experiences.
Roof Material and Longevity
What your roof is made of can determine how long it will hold up. These are some popular roofing materials and how long they typically last before they need to be replaced:
- Asphalt roll roof: 5 to 10 years
- Composite shingle roof: 15 years
- Wood shingle roof: ~25 years
- Standing seam metal roof: 30 to 50 years
- Wood shake shingle roof: 35 to 40 years
- Clay tile roof / Spanish tile roof: 40 to 100 years
- Slate roof: 100+ years
When you apply for insurance, your insurer may ask about the roof surface material and when it was last replaced. This gives them an idea about how much life the roof has left in it.
As you might’ve guessed, newer roofs may fetch you a lower rate with some carriers. Others may simply require that your roof be under a certain age for you to qualify for coverage.
Secondary Water Resistance: What’s Under Your Roof
Some roofs have a layer under the shingles or tiles to provide extra protection in case water gets past the primary barrier. This is called secondary water resistance (SWR) in the insurance and roofing world.
In many cases, SWR barriers can save you money on your home insurance, especially if the barrier is applied with:
- Peel & stick sheets or tape. With this application, the roof deck is sealed with a self-adhering sheet or tape. It must be applied directly to the sheathing to qualify for a discount – not over a layer of felt or other materials.
- Closed-cell foam adhesives. In this case, the foam adhesive is sprayed under the roof deck inside the attic.
How Your Roof Is Attached
A roof deck is the component between the trusses and joints and is the part where roof materials (shingles, etc.) are placed. It’s usually made out of steel, concrete, cement, or wood.
The way the deck is attached to the trusses can determine how well the roof stands up to high winds. As you might’ve guessed, the more wind resistant a roof is, the lower your insurance premium will be.
For insurance purposes, deck attachment usually falls into these categories:
- 6d 6”x12": A 6d nail is 2 inches long. This notation means each 2-inch nail is spaced 6 inches apart at the edge of the roof sheathing panels and 12 inches apart in the field. This qualifies for the lowest insurance discount.
- 8d 6"x 12": An 8d nail is 2.5 inches long. This category means each nail is spaced 6 inches apart only at the edge of roof sheathing panels and 12 inches apart in the field. This attachment qualifies you for the second best discount.
- 8d 6"x 6": An 8d nail is 2.5 inches long. This means each nail is 6 inches apart and gets the biggest insurance discount.
The way the roof is attached to the wall matters, too. Here are the attachment options, from the smallest discount (toe nails) to biggest discount (double wraps):
- Toe nails. These are nails driven diagonally through the side of the roof truss or rafter into the top plate of the wall.
- Clips. This is a metal connector between the truss or rafter and the wall held in place with at least three nails.
- Single wraps. This is a metal connector that goes over the top of the truss/rafter and down the other side. It is secured with at least two nails in front and one more on the back of the wrap.
- Double wraps. This is two separate metal connectors that go over the top of the truss or rafter and are secured to the wall on both sides. It must have at least three nails in the top of the plate on each side.
Find more tips on making your home wind resistant (and reducing your home insurance premium).
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