Our Approach

Seismic Retrofitting Basics

The horizontal (lateral) shaking in earthquakes create the forces that can be damaging to our wood framed homes.  Homes tend to fail in one of three ways - all between the foundation and the first floor joists.  First, the sill plate can slide off of the foundation.  Second, the cripple wall (or pony wall) can fail.  Third, the floor joists can slide off of the mudsill or cripple wall.

There are a few variations on the following themes, but most of our work involves installing proven structural elements to prevent these three types of failure.  These standards and methods, developed in 1999 by Seattle Project Impact, are consistent with other building department permit specs, insurance requirements, and work specified by structural engineers.

It is important to note that work must be done on all four sides of the house, but not necessarily every bit of each wall.

How a Seismic Retrofit Works

Assess your home

After an informative phone call and very rough ballpark budget, you may invite us out to assess your home in person.  During this hour long meeting, we will determine your home's vulnerabilities, and explain what work we will do to reinforce those weaknesses.  After we take notes and measurements, we will prepare and present a fixed price proposal to retrofit your home.  Our bid always includes a building permit and any required engineering, plus finish removal and replacement if needed.


Seismic retrofitting is more than just "foundation bolting", but that's definitely part of it. By this time, we've had engineering done and gotten a permit, had a preconstruction walk with you, and opened up siding or drywall as needed.  During this phase, we install bolts and/or plates to anchor your framing to its foundation. We also install hold down hardware per the engineer's specifications.  Then we'll schedule the required bolt inspection.

Cripple Wall Bracing

Unreinforced cripple walls or pony walls are your homes weakest element.  After we insulate the cripple walls, we install structural plywood shear walls/panels.  It is critical that everything be perfect here - from the type and spacing of the nails to how they are installed; from how we upgrade wall framing to the way we cut the plywood.  Nobody has more experience than our specialized technicians.


The final structural element is to install shear transfer ties or framing clips to keep your first floor joists attached.  After all the reinforcements are in place and we've checked our own work, we'll schedule (and pass) a final building inspection 

Restore and Clean

If we took off any finishes to perform the retrofit, we'll now replace the removed siding or sheetrock and button up all the walls.  Our experts will leave everything weather-tight and "paint ready".  We'll do a final walk through, and you'll get a final invoice.  Finally, we leave you with the plans and permit, as well as a certificate of completion (or your insurance company's form).  Any issues? Let us know and we'll make things right. Everything good?  Please leave us a Google Review!

Choosing a Retrofit Contractor

Sound Seismic:

  • Licensed, bonded and insured.
  • Every member of our team is trained and certified.
  • Experienced with all types of retrofit.
  • References available upon request.
  • Works in conjunction with a licensed structural engineer.
  • Always secures a building permit for retrofit work.
  • Familiar with recent changes to the retrofitting code.


  • Familiar with Project Impact standards.
  • Qualified to address all your structural needs.
  • "One stop shopping" for all retrofit related tasks, including sheetrock & siding.
  • Maximizes dust control, minimizes time disruptions, cleans up properly.
  • In and out in less time than most other contractors.

Ready to retrofit?

Let’s make your home safer

Get a professional evaluation

Call 206-352-5644

Sound Seismic
7543 15th Avenue NW
Seattle, WA 98117

Contractor's license # SOUNDSL836ND

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