You’ve applied for insurance and the company tells you they can’t cover your home because a part of your house has a flat roof with either rubber membrane or other roofing material. What makes insurance companies hesitant to cover a home with this type of roof? The number one reason is that they are more likely to leak. Beyond that, here are some other considerations:
Rubber membrane roofs (the predominant form of flat roofs in Virginia) are more prone to damage as they are made of softer materials that are easily punctured by sharp objects, such as nails, screws, and tree branches. They are also more susceptible to damage from extreme weather conditions, such as hail, wind, and rain.
Flat roofs can be more expensive to repair. When damaged, more often than not they need to be replaced, which is a costlier process.
Installation is more difficult because installers have to cut large pieces of material to go around vent pipes and attic vents, making the risk of gaps more likely.
Unless done just right, most flat roofs have drainage issues over time which can cause structure damage and surface wear if not addressed quickly.
Debris build-up - leaves, branches and moss can quickly accumulate on a flat roof, which requires frequent clearing by the homeowner.
On average, flat roofs have a shorter lifespan, typically lasting only 10 – 15 years.
Types of Flat Roofing
There are three varieties of roofing materials suited for low-slope or flat roofs. Costs vary depending on the type of material used and can run anywhere from $5.00 to $15.00 per square foot. Here are the three types with their pros and cons.
Ethylene Propylene Diene Terpolymer.
Typically comes in a single, seamless sheet (as opposed to multiple, layered rolls) which makes it easier to install.
EDPM can shrink, exposing the layers underneath and allowing water to seep into the structure.
Fire-resistant and holds up well to hail.
Only comes in black, which means buildings will get hotter.
Most affordable option at $5.00-$11.00 per square foot.
Black color may not be aesthetically appealing.
EDPM is a synthetic rubber and the only single-ply roofing option made chiefly of rubber. It is either glued (more expensive), mechanically fastened with screws (more affordable), or secured with layers of stone called ballast (most affordable).
Because EDPM only comes in black, homes using this type of roofing will heat up quickly in hot weather, whether sunny or not, and hold the heat well after sunset. This makes it better suited to cooler climates. It has the longest lifespan of all flat roofing materials, but requires frequent recoating as cracks from swelling and shrinking will occur. Often, if damaged and not detected for a while, the roof and support structure will need replacing, which is why Insurance companies find them less desirable.
Unproven track record
Comes in several colors
Lifespan still undetermined
Difficult and lengthy installation
Heat welded seams
Specialized training needed to install
TPO was first introduced to the U.S. in the 1980s. One of its most attractive qualities is that it has several color options. In hot, sunny climates, a white roof can be much more energy efficient for homeowners.
Installation requires the use of a heat gun to weld the seams together - a process that requires more expertise and time. If the seams need repair, it is not a DIY project and would cost more to get an experienced worker in to handle it.
Many roofing contractors have found that TPO membranes split along the fasteners due to UV light damage. Industry standards for production and installation have only gained traction in the last two decades, so it is still a bit too early to tell if this roofing type will stand the test of time.
Pricing for TPO is more attractive than other alternatives, coming in at between $3.50 and $9.50 per square foot. Depending on your area, this price could increase substantially if the specialized labor required to install it isn't readily available, or if the materials have to be specially ordered.
20 – 30 year lifespan
Potentially harmful to health and the environment
More color options
PVC is another thermoplastic roofing material, like TPO. It is arguably the premier flat roofing material when considering its resistance to fire, wind, and hail. Since it comes in white (as well as several other colors), it is also more energy efficient.
There is some debate about PVC roofing and whether it poses health and environmental risks during its lifecycle. PVC emits dioxins, a known toxic pollutant. It also incorporates chemical phthalates in its structure to increase flexibility. PVC proponents, however, point out it uses fewer fossil fuels during production and lasts longer than most other flat roofing materials, so this offsets its drawbacks.
PVC has a life span of between 20–30 years and costs between $9.00 and $14.00 per square foot. Roofing with higher quality and thickness can cost almost twice that in certain markets, and the project complexity and location will add to the expense.
If you are switching home insurance or purchasing a new home with a flat roof, it is wise to check with your insurance provider to see if: (a) your home is insurable by that company, (b) if there is a surcharge for flat roofs, and (c) if there is a limit on the square footage allowed for living space under a flat roof.
A flat roof may be more economical in the short run for many home renovators or builders, but you could end up paying more for your insurance in the long run.