Windstorm Mitigation: How Architectural Features Affect Storm Resistance

In the past, we’ve discussed how architectural details affect earthquake resistance, and how documenting those details for your insurance Statement of Values (SOV) can help you secure the right insurance coverage at the best rates. So today, we’ll talk about the other common way your building can be affected by risk — windstorm.

Like the seismic resistance details, this information is called “secondary COPE data,” where COPE stands for Construction, Occupancy, Protection and Exposure. And in the case of convective storms, these details focus not only on the potential for property damage from high winds, but also any associated flooding. And it all starts by knowing your property’s Wind Zone and Flood Zone.

So, What is a Wind Zone?

Wind zones are regions of the U.S. that are determined and tracked by HUD and FEMA, with HUD breaking the regions into Zones I to III and FEMA doing so with Zones I to IV. In both cases, the higher the zone number, the higher the average windspeed for that region and the higher potential for wind damage. This information is important for insurance purposes, helping insurers gain a better picture of a property’s risk due to its location and help determine your rates and level of coverage. These zones also help determine construction requirements for these regions. FEMA’s Building Science section, for example, has some really helpful guideline information discussing how to construct buildings to reduce risk of damage in particularly high wind areas.

Then What is a Flood Zone?

Much like wind zones, a flood zone is a designated region of risk tracked by FEMA to predict how likely a particular location will experience flooding. And like wind zones, it’s important to know this information for your property insurance. Your Flood Protection COPE data is designed to reflect how flood-resistant your building may be. It examines how each structure meets flood zone requirements for design and construction — details like whether your building has French drains or retention ponds to help manage storm water run-off. (We’ll discuss further flood-proofing COPE details you should look for in a later section.)

For property in a high-risk zone, you’ll likely be required by federally-regulated lenders to purchase flood insurance to help mitigate any added risk. Your flood risk levels will affect both the amount of coverage you require, as well as the cost. Because all areas have at least some potential for flooding, the risk levels across the U.S. range from low and moderate to high risk. You can check which flood zone your property is in here.

These zones are designated by a letter, with the Special Flood Hazard Areas (SFHAs) — which have a 1% or greater chance of being flooded in a year — specified with an A or a V.  If you’re in one of these SFHA zones, you are legally required by your lenders to purchase and maintain flood insurance. Zones are categorized as follows:

• Zone A99 ‑ Special flood hazard area with protective systems in progress, like dikes, dams and levees, which are complete enough for insurance purposes.
• Zone A ‑ Special flood hazard area where water surface elevations haven’t been determined.
• Zone V ‑ Special flood hazard area with velocity where water surface elevations haven’t been determined but tidal floods are common. These are largely coastal high hazard areas.
• Zones B, C, and X ‑ Minimal to moderate flood hazard area. Here, flood insurance is available but not required.

By knowing your zone, you take the first step in determining your flood risk.

Construction Quality

When it comes to secondary COPE characteristics, Construction Quality becomes an overarching factor for mitigating the risks of windstorms. It is the overall quality, design and/or condition of a property being valued for insurance purposes. There are a few factors that help determine this quality:

For buildings intended for commercial purposes, they are required by law to have a “certified design and construction.” That means that the group that provided integrated design and construction of, for example, a high-rise office building used well-trained, certified professionals throughout the project, and this has been verified. It holds the construction and design to a high level of safety standards.

For buildings designated for residential purposes, these are required by law to have a “certificate of occupancy.” That means a local government agency or building department has certified that the building is in compliance with building codes and other safety standards, making it a habitable place to live.

Features that would indicate a lack of habitability would include buildings with damaged foundations, severe water damage and mold, exposed wiring, buildings that are condemned, and so on.

Building Exterior — Roof

A structure’s roof features many important secondary COPE details that can either potentially fail in a windstorm or be huge asset for windstorm mitigation. Some important questions to ask yourself about a structure’s roof include:

• What is the roof geometry? This is the shape and pitch of the roof. Common roof types include gable, gambrel, mansard, hipped, flat and shed roofs, and the shape and construction of each can affect just how much windstorm mitigation it will provide. For instance, more peaked roofs with jutting angles are less wind-resistant but can shed rain more efficiently, while a flat roof might be more wind-resistant but more subject to rain pooling and leaks.
• What is the roof framing type? The roof frame is the material used to create the structure of the roof. Roof framing tends to be made of wood purlins, heavy- or light-gauge steel purlins, precast concrete, poured concrete or cast-in-place concrete.
• What type of roof anchors were used? Having the correct (and correctly installed) roof anchors for the type of roof is important to maintaining roof security in high winds.
• What material is the roof covered with? Common roof coverings include lightweight concrete fill, built-up metal sheathing or built-up ballasted coverings. A ballasted roof system, for instance, where gravel is used to anchor the roof materials, tends to be highly wind-resistant, where a non-ballasted system might not offer those same benefits.
• If roof sheathing was used, how is it attached? Is a wooden roof connected to the roof sheathing by a nail or a screw and what type? This can affect the security of the roof during a heavy windstorm.
• What about shingles? If there are shingles, knowing whether they’re made of asphalt or wood helps determine how resilient the shingles will be to high winds or extensive downpours.
• No shingles? Then check to see if the roof is covered with a single-ply membrane, for that extra layer of windstorm mitigation.
• How old is that roof and has it been maintained? Knowing the age, condition and maintenance of all your roofing materials is important to help determine just how that roof will stand up to high winds and powerful rains.
• What about roof parapets or chimneys? These barrier wall extensions on roofs, terraces or balconies can be subject to damage due to wind sheer or, when poorly-maintained, cracks and chinks in mortar can let in stormwater.
• And is there roof equipment, and how is it braced? Particularly for hurricane-prone areas, making sure roof equipment is properly braced to endure the high winds is critical.

By adding these secondary COPE details related to roofing into your insurance statement of values, you can help create a more accurate picture of your property for your insurer.

Building Exterior — Windows and Doors

Openings in a building’s structure can be points of vulnerability in windstorm mitigation. That’s why many doors and windows have been designed with certain features to remain strong in the face of high winds, reducing the risk for potential rain damage and flooding within the structure. Secondary COPE details to pay attention to here include:

• Is there any opening protection? How much protection is provided to, or by, the glass and windows from windborne debris?
• Is the glass laminated, impact-resistant glass? Particularly for hurricane-prone areas of the U.S., this feature can be very important. The glass is bonded with a protective interlayer of polyvinyl butyral (PVB), which makes the glass stronger, helps with insulation and noise, and offers UV protection. If the outer layer of glass does break — even with a direct impact by an object — the shattered pieces adhere to the PVB film. The glass may crack but it still won’t expose the building to wind and water.
• Or is there insulated, laminated non-impact glass? In this type of window, a single extra pane of glass is added to the laminated safety glass and sealed with a layer of gas inside (commonly argon) to help deal with temperature differences between the indoors and outdoors, and offer noise reduction and energy efficiency.
• Are there resistance/impact-rated doors? These are exterior doors specifically rated to resist hurricane force winds and pressure, as well as flying debris. To be impact rated, the door design must pass an official High Velocity Hurricane Zone (HVHZ) test.

Building Exterior — Outdoor Equipment

The objects attached to a building can be just as important to examine for windstorm mitigation as the building itself. Don’t forget to include these secondary COPE characteristics in your appraisal of the building exterior:

• Is there mechanical/electrical equipment attached to the side of the building and, if so, how is it attached? This can include items like electric meters, satellite dishes, antennas, etc. Knowing what’s attached to the side of a building, how it’s attached, and its condition is critical to determining how high the risk for property damage will be in the event of a severe windstorm. Improperly secured equipment can become a wind missile in a severe windstorm, while electrical equipment that’s not properly protected from water can short, fail and cause dangerous conditions.
• Is there ground level equipment around the building and how is it secured and protected? This might be an HVAC system or backup generator. Is there fencing around it? Protective shrubs? What is the possibility for flood damage?

Building Exterior — Structures on the Property

Your property risk isn’t limited to your building itself, so it’s important to take into account the secondary COPE details for other structures that sit within the property boundaries, as well. This can include items like:

• A detached garage, shed, pool, or guest house
• Fencing, gazebos or a pergola
• An outdoor kitchen
• A front gate or water fountain
• Fences, carports, screen enclosures, lanai

By including these in your SOV, you form a more powerful, accurate picture of your risk profile.

Additionally, you should examine the area and assess the following:

• Are there any potential wind missiles around? That would be anything that could be launched by a strong wind and cause damage to your building and its structure. Wind missiles fall into three categories. Lightweight wind missiles are items like roof gravel, tree branches or piece of lumber, and because of their light weight, they can be propelled great distances. Medium class wind missiles might include small diameter pipes, steel roof joists and small beams. Heavyweight missiles include utility poles, large pipes, automobiles, and railroad cars, etc.
• How close are any trees to your insurable property? And how dense are they? What are the chance of them damaging your property in high winds?
• Are there any permanent barriers like floodwalls or levies? Floodwalls, constructed of concrete or masonry form a barrier between a building and land at high risk for flooding. Levies are created from compact layers of soil and an impervious core but function similarly to floodwalls. These can all be important features for flood mitigation.

Building Interior

While windstorm mitigation focuses heavily on the exterior, there are interior COPE details that are equally important to note, such as:

• Is there a basement or is the building elevated above a flood level? In high-risk flood zones, designing a building so its lowest floor is at, or above, the flood level can be a useful method of flood protection.
• If there is a basement, has dry or wet floodproofing been done? Dry floodproofing works to reduce flood damage by adding wall sealants to concrete or masonry foundations to make the structure watertight. It also involves shielding the openings. Drainage and pumps are used to deal with flooding, should it occur. Wet flood proofing, in contrast, lets the storm water flood through the lowest level but uses flood damage resistant materials and protects equipment vulnerable to water damage.
• What kind of frame foundation connections were used? These can be stacked block, pier and beam, slab on grade, or in the case of smaller structures like sheds, no foundation at all. How a building is connected can be an important durability issue when that foundation is exposed to heavy flooding.
• How vulnerable are the building’s contents if exposed to flooding?
• How vulnerable are the building’s contents if exposed to wind?

COPE-ing with Your Windstorm Data Gathering

By documenting the COPE property details for windstorm and flood for your insurance provider, you help create a thorough, accurate view of your risk levels. This means you not only have the opportunity to right-size your property insurance coverage, but you might just be blown away by better rates!

PS- If you need assistance gathering these details, contact Centurisk about our property valuation services! We’d be happy to discuss.