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Fresh Organic Fruits and Vegetables “Sprout-Up” in Downtown Oakland
 
Hohbach-Lewin, Associate Principal, Kevin Morton, SE was just one of the many luminaries who showed up to celebrate  “Sprouts Farmers Market”  grand opening in the recently completed Shops on Broadway Building (Architectural design  by Oakland based  Lowney Associates) located at 30th and Broadway situated between Oakland’s Autorow and downtown. Following an urban retail trend of densifying sites, Oakland joins Berkley, Burlingame, Long Beach, Mountain View and Pasadena as sporting new grocery stores on tight urban sites with roof top parking designed by Hohbach-Lewin engineers.  

In order to accommodate the large spans sought by Sprouts facilities staff requirements, pre-stressed pre cast double tee girders were employed in the structural solution. “The pre-cast solution provides a clean, structurally efficient system," Kevin explains, "the higher ceiling demanded by the relatively large retail use allows for the employment of the double tees without adding costs – the tees are strong enough to support the parking above and with proper planning also shorten the overall duration of construction. This is why we have gone to this solution now for our last five similarly configured urban grocery store projects." The tees are covered with a 4 inch thick concrete topping slab to tie them all together and provide the seismic force transfer capacities dictated by California’s strict seismic design criteria.
How to keep Godzilla El Niño from dampening your day:
 
Hohbach-Lewin has utilized pre-cast concrete systems on numerous urban infill parking over retail facilities throughout California during the past several years and until recently the waterproofing hasn’t seen much action. Given the recent increased precipitation (see reasons to go skiing with us below), we felt the need to expound on some of the systems/challenges associated with providing reliable waterproofing for this construction type.    
 
Typically two systems have been utilized to prevent water from intruding into the retail space. 
 
Single Elastomeric membrane: An Elastomeric water proofing membrane/traffic coating is applied directly on top of the structural topping slab. This requires less upfront costs to install and is easier to access for maintenance. It also adds less mass to the building when compared to the alternate double slab system described below. Typical warranty time for this system is 10 years. “Soft cutting” the topping slab above the double tee joints as soon as possible after the initial concrete topping slab sets (ideally within two to three hours of the pour – before initial concrete shrinkage cracks can occur) and tooling the expansive joints in the correct manner is of paramount importance. The joint consists of a “v-groove”, so configured so the expansion joint filler adheres to the sloped sides only (and not the bottom of the groove) – this allows for some movement in the joint without damaging this critical water proofing bead.
Redundant Dual Slab System: In addition to the structural topping slab and v-grooves (as described above) a thicker waterproofing system consisting of a membrane, separation sheet and drain mat is placed underneath a secondary concrete wearing surface (3 to 4”). The concrete wearing surface protects the waterproofing assembly and prevents it from seeing direct contact with traffic. This strategy results in an approximately 30 percent increase to the overall dead load of the roof structure (and thus results in a significant net add to the seismic mass the building structure must be designed to resist). Besides the direct costs associated with the concrete wearing surface, the increased mass results in increased demands (and thus cost) to the structure. Although less likely to require maintenance, if a problem arises, accessing the waterproofing membrane is more difficult for obvious reasons. Typical warranty time is 20 years.
 
The more rugged Redundant Dual Slab System is most commonly used over retail usage.
Hohbach-Lewin's 9th Annual
Ski Trip - March 3rd!

 
Mother nature has made up for her dismal ski season last year by dumping 132” of powdery goodness on the Summit of Sugar Bowl!  Last year we had to cancel the annual Hohbach-Lewin ski trip due to lack of snow - but we won’t have the same problem this year! The only way we’re cancelling this trip is if a blizzard comes through the day of which makes travel impossible and even then we’re still going!

Our ski trip is mostly populated by clients and friends. We are piling into the Hohbach-Lewin bus at 5am sharp from Palo Alto, and 6am from the El Cerrito BART station. The fee includes bus fare, a lift ticket, food and drinks, and an all-around great time! Please contact Mike Resch to get more details and to secure your spot!
Copyright © 2016 Hohbach-Lewin, Inc., All rights reserved.


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