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Commercial Seismic Retrofit

Many commercial buildings constructed before 1987 are not considered capable of resisting the forces exerted by an earthquake.

Living in earthquake territory, it is widely understood that certain types of older buildings are inherently dangerous as they are susceptible to structural damage, or even collapse, in the event of an earthquake.

Typical types of older buildings that benefit from a seismic retrofit include the following:

  • Concrete tilt-ups
  • Soft-Story Structures, such as those with tuck under parking or large store fronts at the 1st floor
  • Unreinforced masonry buildings (URM)
  • Non-Ductile concrete buildings
  • Retail buildings (older built of block or concrete)
  • Historical buildings
  • Parking Structures

To protect a building's value as an investment, including the tenants and their operations, maintain the building's marketability and decrease liability, it's important to assess your building's earthquake risk and perform a seismic retrofit when recommended.

Sometimes a seismic retrofit is performed voluntarily, yet other times, outside forces trigger the need for a seismic retrofit; including a change of the buildings use or occupancy, as required by the city, or as required by lenders and/or insurance companies before they will lend or insure these types of properties.

Not all seismic retrofits are the same! Because we work with older existing buildings, the level of strengthening or seismic retrofit can vary, based on the goal of the building owner, the insurance company, or the lender's requirements.

It's important to know what level of retrofit you're receiving, and that it will be accepted within the industry by other structural engineers, lenders, insurance companies, etc... You may want to get a second opinion or a peer review of the seismic plans before performing the work to confirm that the retrofit meets the intended goal/criteria.

When limited financing is the primary concern, a goal for the seismic retrofit may aim to achieve the "best value" for your retrofit dollars. One can always improve and strengthen their building, but sometimes the cost of such becomes too expensive and may prohibit any strengthening measures. Rather than doing nothing at all, there are usually incremental steps that can be taken to seismically strengthen the building, without addressing all of the building's deficiencies at one time. This is not always an option, but it can be discussed on a case by case basis.


Top Five Reasons to Choose Saunders Seismic as
Your Seismic Retrofit Contractor:

  • 34+ years experience
  • In-house, experienced personnel (not subcontracted)
  • Specialists in working with existing buildings, including sensitive tenants and occupied spaces
  • Excellent safety mod rate
  • Licensed in California, Washington, and Oregon

Seismic Retrofit Concrete Tilt-up

A seismic retrofit for a concrete tilt-up building is one of the most economical retrofits. The cost per square foot price can be quite competitive, depending on a building's characteristics.

Early designs of these types of buildings (circa mid 1990's), only had limited or weak connections at the roof to walls and continuity ties. With current engineering knowledge, it is well understood that these buildings need to be retrofitted to make them safer and perform better in the event of an earthquake. Because of the heavy concrete walls, in the event of an earthquake, these walls want to pull apart from the roof, creating a collapse hazard. Evidence from previous earthquakes suggests that these buildings can be quite dangerous during a seismic event and suffer extensive damage.

Quite often, concrete tilt-up buildings are occupied, with tenants conducting business inside. Saunders Seismic specializes in working in occupied spaces, particularly with sensitive tenants and/or operations. We've worked in all types of facilities, including commercial manufacturing, industrial, food processing plants, freezer and cold storage facilities, and warehouses. No project is too simple or complex - we can excel in either environment.

Saunders can provide assistance with conceptual planning for the scope of the retrofit and preliminary pricing, as well as provide a competitive bid based on completed drawings, depending on the stage of the project.

A typical retrofit for a concrete tilt-up building would include some of the following components:

  • Roof to wall anchors
  • Continuity ties
  • Roof nailing, if needed or scheduled as part of a re-roof
  • Steel braced frames and concrete footings, if needed based on the building's geometry

Seismic Retrofit Soft Story

Several building types are known to be vulnerable in the event of an earthquake, including those with "soft story" conditions. A soft story condition occurs when a building has an open first floor (such as ground level parking, subterranean parking, or an open store front with glass and minimal structural reinforcement) on at least one elevation, if not more.

Examples of buildings with soft story conditions include:

  • Multi-Family Apartment building with tuck-under parking or subterranean parking
  • Retail center with a large store front on the first floor, and living or business operations on upper floors

The general "openness" of the first floor creates the opportunity for structural damage during an earthquake because at least one elevation of the ground floor level lacks proper shear reinforcement to support the building. The design criteria was weak when these buildings were originally constructed; however, today through research performed following major earthquakes around the world, the structural engineering community understands that these buildings must be reinforced or seismically retrofitted.

Following the Northridge earthquake numerous apartment buildings with this type of construction collapsed causing damage and harm to both the building and the building's occupants. From our understanding, there are still several cases of unresolved litigation or insurance claims.

Saunders Seismic is an expert at retrofitting buildings with tuck under or soft story conditions. Watch the following interview recorded by NBC in the Spring of 2011.


Following is a list of typical reinforcement strategies:

  • Adding a steel moment frame, concrete footing and drag line to keep the 1st floor from rotating and collapsing
  • Adding plywood or concrete shearwalls to existing or new walls
  • Replacing existing support columns
  • Adding continuity ties
  • Removing and replacing finishes as required for our work


  • 34+ years experience
  • In-house, experienced personnel in structural work
  • Specialists working with existing buildings, including sensitive tenants and occupied spaces
  • Excellent safety mod rate
  • Licensed in California, Washington, Oregon, and Nevada (Nevada license currently inactive)

Roof Condensation Repairs

Roof condensation damages are a phenomenon commonly seen in industrial tilt-up buildings where a radiant barrier (foil insulation) is installed beneath the roof's framing members, trapping the framing bays and not allowing for proper air ventilation.

Roof condensation is moisture that develops at the roof ceiling area and is trapped by foil insulation or other types of radiant barriers and, if left untreated, can destroy the entire roof structure! This problem can be a 50-cent or a 10-dollar per square foot problem, depending on how long it goes uncorrected. Certain types of tenant operations can exacerbate the problem as well.

Typically the first stage of condensation issues includes "oxidation" of the aluminum alloy sub-purlin hangers, and is evidenced by "white" markings on the hangers. Usually the smaller, sub-purlin members show signs of corrosion first, and are typically covered by foil.

The second stage or progression of condensation issues includes "rust" on the metal hangers that support the framing members and is evidenced by red/orange rust and streaks on the iron hangers. Black streaks can also be seen running down the side of the lumber below the foil. This is most often evidenced before the rusted or corroded hangers are spotted.

Saunders works with several engineers that specialize in solutions for this type of damage and can help create a plan to repair existing hardware or, if necessary, replace it with new hardware or ledgers, depending on the severity or extent of damages.

Typical repairs for roof condensation damage include:

  • Remove or vent the foil insulation (this will help prevent/slow the corrosion process and protect the roof system's structural integrity)
  • Scrape and paint the hangers showing signs of rust
  • Add/modify existing hangers that supports the purlins
  • Add/modify existing hangers that support the sub-purlins (ledgering)
  • In severe cases, remove and replace roof framing members as needed

Roof Framing Repairs

Roof framing repairs may or may not be directly related to seismic retrofitting and can be made on any type of building, such as concrete tilt-up, masonry, steel, or wood-framed buildings.

Common causes or reasons to perform framing repairs:

  • Correcting damage caused by roof condensation, including repair or retrofitting of hangers or ledgering sub-purlins
  • New roof installation and wanting to correct roof condensation damage by replacing plywood sheathing and/or adding additional roof nailing
  • Reducing the load on key beams that are overloaded by heavy rooftop equipment or hanging equipment
  • Reducing the load on key beams that are overloaded by old design criteria or poor lumber
  • Reinforcing or replacing aging beams that are deflecting or breaking
  • Replacing or reinforcing beams that are sagging from collected water on the roof
  • Repairing or replacing beams that have been exposed to "cooler" or "freezer" conditions, without proper insulated panels, causing severe condensation damage
  • Tenant operations that create a heavy moisture content and/or heat, thus damaging the existing roof framing members overtime
  • Old, vacant buildings without proper ventilation that experience significant corrosion to framing members

Typical Types of framing members requiring repair:

  • GLB repairs
  • Purlin repairs
  • Subpurlin repairs
  • Truss repairs
  • Plywood Roof Sheathing

Typical repair methods include:

  • Adding additional steel or lumber to existing framing members
  • Adding tension cables to existing GLB, purlins, and beams
  • Injecting epoxy and/or dowels into wood members and applying preventative coating to combat against wood rot
  • Adding support columns and/or footings
  • Replacing structural members (worst case scenario), beams, roof sheathing, etc...

Structural Repairs

In addition to seismic retrofit, Saunders specializes in structural repairs for existing buildings, including rough carpentry, structural steel, and structural concrete.

Typical types of structural repairs performed include:

  • Truss repairs (including post tension)
  • Glu lam beams (including post tension), repairs and replacement
  • Purlin and sub-purlin repairs and replacement
  • Concrete connections (footings, gradebeams, walls, etc...)
  • Steel connections (columns, beams, braces, plates, posts, etc...)
  • Moment frames
  • Shear walls (plywood or concrete)
  • Roof sheathing
  • Crickets
  • HVAC platforms
  • Repair damages to wood, concrete, and foil insulation caused by water, age, and stress (roof condensation)

Roof Coatings

Construction regulations effective in October 2005 require that air-conditioned spaces with re-roofing use an approved reflective roof coating. Saunders Commercial Seismic Retrofit has developed a unique roof coating system that not only meets new regulations, but increases the quality and durability of a structure's roof while saving owners plenty of money.

Saunders' reinforced reflective roof system has many advantages over traditional roofing renovations:

  • Tax write-off: The entire cost can be written off in the first year (check with your accountant)!
  • Energy savings: With our reflective coating, your commercial property may qualify for a California Energy Rebate, saving you even more money!
  • No re-roofing required: Since a Saunders coating system does not require roof removal, the interior of a building is not subjected to weather and debris. This allows building operations to continue in a normal fashion without interruption. Our roof coating system is also good for the environment!
  • No hot asphalt required: Without the need for hot asphalt, building occupants are not brought into contact with noxious fumes!
  • No heavy machinery required: Because Saunders' coating system does not utilize heavy machinery, the entire process is much quieter than that of other roofing systems!
  • Cooler structure: Saunders' roof coating system keeps buildings without air conditioning cooler in climates where the sun blazes daily. Air conditioned buildings under our two-ply system have substantially lower energy costs!
  • Longevity: Saunders' roof coating system prolongs the life of your current roof and comes with a 10-15 year warranty!
  • Easily and indefinitely renewable: As with any roofing system, roof coating materials eventually break down and need to be replaced as years go by. With our system, however, new coatings are remarkably easy to add!