Portland Homeowners, Get Your Seismic Retrofit!

Knowledge of a potential big earthquake in the Pacific Northwest has been circulating in geological circles for many years, but the public got a big jolt when news stories began sounding the alarm last summer. As we wrote about on this real estate blog in August, studies of the Cascadian subduction zone fault line show that there’s a 10% chance of an earthquake around magnitude 9 hitting Oregon in the next fifty years. Smaller quakes have an even larger likelihood of occurring.

In wake of growing earthquake awareness, Portland officials and homeowners have not assumed the hiding-under-the-desk position. The City of Portland applied for FEMA funds to help homeowners pay for seismic upgrades to their homes, according to the Oregonian. Four thousand Portland homeowners expressed interest in the funds. In March of this year, the news was announced that Portland was awarded about half a million dollars, enough to subsidize half the cost of a seismic retrofit for 150 of those homeowners. According to the Oregonian, “That will only put a small dent in the approximately 100,000 Portland single-family homes that are potentially vulnerable to a major earthquake, according to city figures, but it’s a start.”

Curious what it takes to seismically retrofit a home? Which homes are most likely to need retrofitting? As a Portland real estate agent, I wanted to know the answers to these questions too, so I did a little research. Here’s what I found out.

Seismic Retrofitting in Portland

The Portland nonprofit Enhabit is administering the FEMA funds, and they’ve prepared a handy Earthquake Preparedness in the Northwest guide which is available for free through their website. They recommend getting an assessment from a seismic professional to determine what upgrades your home might need. The guide also provides some basic guidelines about which homes are at risk. As a general rule, homes built before 1974, when seismic building codes were enacted in Portland (1980 in Washington), are least likely to survive an earthquake. However, that doesn’t mean you’re in the clear if your home is newer.

Common Points of Failure

Oregon’s top natural resource has always been trees — and that means homes here are built with wood frames. That’s a good thing! Unlike brick, masonry or stucco, wood is flexible and moves with the ground underneath it. Generally speaking, wood-framed homes are less likely to collapse in case of an earthquake, and their walls can be more easily reinforced.

The downside is that all wood frames must sit on something, and in most Portland homes it’s a concrete foundation. Problems arise when homes detached from their foundations or “cripple walls”, which are short walls that elevate homes slightly above their foundations. Another unsafe situation is when rooms are added on above garages or porches, which lack sufficient reinforcement to support them when the ground begins to shake.

The foundation itself can also be problematic. Cracks, crumbling areas and missing pieces are all indications that failure could be imminent.

Remediation & Cost

There are two main methods for reinforcing or reengineering a home that is at risk for failure in an earthquake. If the home has a strong foundation and meets other criteria, your seismic contractor will take a prescriptive path, performing specific upgrades to strengthen the structure. These may include:

• Bolting the home to its foundation. It seems all too simple, but huge steel bolts are usually the best bet against the most common problem for Portland homes — the risk of sliding off the foundation. The bolts can be placed vertically, through the bottom of the wall and the top of the foundation, or horizontally if space does not permit vertical bolts. Horizontal bolts are mounted into foundation plates that attach the wall and the foundation. These can be installed either on the inside of the basement or on the outside.
• Reinforcing framing. Your seismic contractor may recommend adding brackets and anchors to the existing structure of your home, especially along foundational joists and beams. If your home has a porch and/or historic columns, additional posts and beams can be built inside them to keep them standing for decades to come.
• Preventing secondary earthquake damage from water heaters and gas lines. Strapping down the water heater can not only prevent damage from this heavy object falling through the house, it will also serve to keep the water in the water heater where in can be used as an emergency supply. If your home uses natural gas, it might be recommended to have a valve installed that allows quick shutoff in case of a break in the line somewhere in your home.

Deferred Maintenance is Quake-Bait

If your home is in need of a new roof, foundational repairs or other major upgrades, seismic experts recommend taking care of these as your first move toward earthquake preparedness. If there’s a chimney you’re not using anymore, removing it will greatly increase your safety during an earthquake. And it won’t matter how solidly your home is bolted to the foundation if the foundation itself is crumbling. Not only will these improvements help you sleep at night knowing your home is safe, they will do wonders for your home value when you decide to sell your home.

Portland Home Values Unshaken

Although the general public now has more of an idea of what the natural disaster potential is for the Pacific Northwest and Portland, it hasn’t kept people from moving here! If you’re selling your Portland home, buyers may want to know if it’s earthquake-safe, so at least consulting with a seismic contractor may be to your advantage. If your home was built before seismic building standards were put in place for Oregon or Washington, you may want to get some quotes for what it would cost to retrofit. As awareness about the Cascadian subduction zone and other fault lines grow, having an earthquake-safe home may become a top selling point!

If you have other questions about how earthquakes might affect your home sale, contact your Portland real estate team today!