In our previous blog, we discussed how the owner/landlord of a Soft Story building hires a structural and/or soil engineer and a construction firm to carry out a Soft Story retrofitting project. In other, earlier blogs, we also discussed the required steps to comply with the requirements of the City of Los Angeles’ Soft Story Retrofit Program and the Tenant Habitability Program (“THP”) (see links at the end of this page). Today, we’ll explain what a typical Soft Story retrofit project looks like!
Construction Phase One: Demolition and Excavation Stage
During the demolition and excavation stage, your Contractor will demolish some of the building’s existing stucco finish to uncover the exterior walls and ceiling of the building in those areas where the retrofitting will take place (for example, above and around where steel columns will be placed). At this time, construction professionals will also saw-cut the concrete slab surface and will excavate below the slab to dig a trench that can take a steel rebar and concrete “grade beam” and/or “pad footing”.
Once demolition has taken place, the Contractor is required to call for a pre-construction meeting with the project Engineer-of-Record and the City Inspector, to determine whether any Plan changes are necessary (for example, to review the precise placement of steel columns, or remediate termite damage uncovered after the stucco finish was removed, etc.).
Note that it is important that the Contractor you choose removes all debris from the project site at the end of each day, as well as properly and safely cover over the excavated trenches. This is done both to maintain the safety of the job site, as well as to allow Soft Story tenants to park their cars each evening!
Construction Phase Two: Temporary Shoring, Steel Column and/or Steel Beam, as well as Grade Beam and Rebar Placement
After the project Engineer and City Inspector have given their “thumbs up” to have the Contractor proceed with the project, the Contractor will deliver to the job site the necessary welded steel “cantilever columns” or steel “moment frames” and beams, that will be attached to the building by welding them into an existing plate or beam. This new steel structure will connect between the building and its new foundation.
At this time, the Contractor will also deliver the steel rebar that will be placed into the excavated trench, to reinforce the concrete grade beam and/or pad footing foundation. All this concrete, once reinforced with steel rebar, will underpin the steel columns and beams, helping to prevent them from shifting during a seismic event!
The Contractor will also typically erect temporary wood or steel shoring beams to stabilize the structure during construction. This temporary shoring is simply a support structure that uses large wood or steel beams temporarily, until they can be replaced with steel cantilever columns.
Once the steel cantilever columns or moment frames are in place, the Contractor will place the rebar in the excavated trench to form a concrete grade beam. When the City Inspector approves the work, the Contractor can proceed to the concrete pouring phase. At this point, the Deputy Inspector will evaluate and approve the concrete mix and the contractor will go ahead and pour concrete into the excavated trench.
Construction Phase Three: Concrete Curing and Stucco Installation
Once the concrete is poured into the excavated trench and molded to create the rebar-reinforced grade beam and/or pad footing, it is allowed to “cure” (basically, to dry out) for a number of days. At this point, the Contractor can proceed to add structural plywood to the exposed ceiling of the building to reinforce and strengthen those exposed areas, if necessary. Also at this point, the Contractor can patch areas of previously-removed stucco with a new stucco finish. Once the new stucco is allowed to cure, the contractor can have the stucco painted to match the previous painted finish.
In Next Week’s Blog!
In our next blog entry, we’ll discuss the required Lead and Asbestos testing, Seismic Shut-Off Valves, Deputy Inspections, Structural Observations by the project’s Engineer-of-Record, and how Weinstein Construction can assist you with the process for recovering up to 50% of the costs of the Soft Story retrofit!
Meanwhile, if you wish to discuss your Soft Story needs with one of Weinstein Construction’s Soft Story experts, please call Angela at (800) 862-6582. At this time, we can also schedule you for a free, no-obligation inspection and estimate to retrofit your Soft Story structure!
Other Weinstein Construction blogs on Soft Story Retrofits and the Requirements of the City of Los Angeles can be found below: