SNW provides a variety of services for seismic retrofitting, depending on your house’s unique needs. We can upgrade your cripple wall and/or your foundation, all depending on what makes your home meet seismic protection. Extra upgrades won’t be done unless you ask. For typical projects, our process starts at evaluating your house and providing a fixed-price quote. Afterwards SNW can begin with engineering the right solution, with your approval. Once we have the right permits and Professional Engineering drawings, we work with you on starting construction on your home so that we minimize the interference with your daily life. Earthquake retrofitting can be a dirty and noisy process, but we know how to keep it to a minimum as possible to get the job done. We perform daily checks and cleaning. When it’s time to complete the project, we’ll bring out the inspector to make sure your home is done right and meets local, state, and federal codes. Once we’ve performed our final walk-through with you and it meets your satisfaction, we’ll do a final clean up, remove all excess material, and have the refuse bin taken away. Seismic Northwest (SNW) is a seismic retrofit company with over 20 years of carpentry and seismic retrofitting experience and knowledge. SNW, is proud to serve Western Washington, from Bellingham to Olympia, and Kitsap County. We perform retrofits for residential homes, commercial buildings, and seismic-specialized engineering. We use structural engineers to make sure we provide you the best retrofit for your home or business. Our crews have advanced their skills through field experience and communication, and they pride themselves on quality and professionalism. We start our services by providing a free, “zero obligation,” assessment of your home or business, and our assessments come with a fixed-price quote. We’re committed to delivering our services on time and within budget. We use top-of-the-line tools and construction material from Simpson, and our crew members are among the best in the business.
What is residential retrofit?:
The primary purpose of seismic retrofitting is to keep your home or business safe from being displaced off of its foundation by an earthquake. Western Washington is on a dormant fault line, which home construction experts previously didn’t consider when building the frames and foundations of our homes. Today’s experts understanding of earthquakes have improved, giving us the opportunity and knowledge to retrofit any home to prevent failure from future seismic activity.
How Homes and Businesses Suffer Seismic Failure:
Homes and businesses typically fail because of damage to the wooden frames. The three main types of failures are called sliding, racking, and overturning. These occur at the foundation or the cripple wall (the wall section between the foundation and first floor joists). The cripple wall is commonly considered the weakest part of older homes. Sliding occurs when the home slides off of the foundation or cripple wall. Racking occurs when the cripple wall buckles and collapses. Finally, overturning happens when the house topples from the foundation or cripple wall.
Cripple Wall Seismic Retrofitting Needs and Solutions:
A cripple wall is the short wood frame wall in the crawl space between your home and the foundation. The height of the cripple wall can be a few inches to several feet. This area of any unprotected home (or business) is the number one cause for seismic failure. If the cripple wall collapses, typically the house will fall to the ground and foundation. In some cases a home may not have a cripple wall. In this scenario, the home is somewhat less likely to be displaced from its foundation, but the risk is still considerable. The first floor frame and foundation are connected by “toenails,” which can often result in sliding. While the house may only slide a few inches, portions of the floor may sag and utility connections may be severed. When a home has a cripple wall there are two typical methods of seismic retrofitting: bracing and foundation hold-down brackets. The first step is bracing, or stiffening the cripple wall to keep it from collapsing. This process is similar to building strengthened walls and flooring around the cripple wall’s joists, thus turning the weakest point of a home into a shear wall, or a wall capable of withstanding shear forces (earthquake forces). Sometimes a home will require more than bracing, needing foundation hold-down brackets. These are right-angle brackets and bolts that connect the cripple wall to the foundation, preventing a shear wall from lifting or rolling. Simpson Hold-downs are installed at the ends of shear walls, held down by epoxy-anchored bolts. If a home does not have a cripple wall, Simpson anchors make all the difference in the world. These homes require special inspection because of the different options for the different home situations.
Foundation Seismic Retrofitting Needs and Solutions:
Foundation seismic retrofitting uses bolts and plates. Bolts are added through the sill, or mud-sill, and into the foundation. The sill is the wood that rests flat on top of the foundation, where vertical components are installed. Bolts are added because there may be no existing bolts, or the existing bolts are not adequately installed. They may be weak or spaced too far apart to resist seismic activity. In these situations, expansion bolts and epoxy-set bolts are used. Expansion foundation bolts are the basic bolt used in retrofitting. They cost less, but they require a good foundation to work well. Homes with newer foundations or foundations in good condition are well suited for these types of bolts. Epoxy-set foundation bolts work best in older homes due to their weaker foundations. These are usually longer than expansion foundation bolts, and set in an epoxy resin inside the foundation. They also work better for an uplifting forces from an earthquake.
More Benefits to Seismic Retrofitting:
Besides the assurance that your home has the maximum structural preparedness a seismic retrofit can offer, you may be eligible for earthquake insurance. You’ll need to ask your insurance agent for confirmation. Another benefit to earthquake retrofitting is that reduced or no damage to your home means little to no waiting on a contractor to repair your home in the lengthy aftermath of an earthquake.