Jim Klinger, Concrete Construction Specialist

The Slab Newsletter July 2025

Question:  We just returned to our office from a mandatory project kick-off meeting with major project stakeholders, including the Owner (a well-known, high-profile winemaker), the architect, the structural engineer, and the general contractor (GC). Based on a few of the meeting discussion topics, we now find ourselves in a difficult situation regarding jobsite access and logistics. We are hoping a call to the ASCC Hotline will provide some relief.

We were originally issued a Letter of Intent (LOI) for this project, which we successfully bid during the fall of 2019--before the COVID pandemic hit and caused the winemaker to suspend all work on capital construction projects (including new construction, existing facility upgrades, and retrofits). Groundbreaking on our project was slated to occur in January 2020, with our mobilization onsite scheduled soon thereafter.

When we received notice from the GC that the project was being shelved, we were assured that the job was only being suspended--not cancelled--and that the Owner didn't want any part of putting the job back out on the street for a rebid.  In other words, this was our job, only with a start date unknown. In addition, we were assured by the GC that all stakeholders would be equitably compensated for all material escalation costs, supply-chain costs, labor escalation costs and so on related to the pandemic shutdown as outlined in ASCC Position Statement #45- "Managing Concrete Projects: Concrete/Steel Price and Delivery Volatility Risks".

Now here it is some five years later; and--true to their word--the financing to cover all of the escalated project costs for all parties is approved and in place. The mobilization date for our scope is now slated for October 2025. With that bit of good news, then, what could be so difficult?

Here's some background information. 

We are a well-established concrete "place-and-finish-only" contractor. But we are slowly expanding our scopes of service. We routinely perform pump-place-finish work on large commercial projects, including concrete high rises, structural steel towers (slabs on metal deck), and small school projects.  This project will be our first tilt-up job. At bid time, we decided to venture into tilt-up work because one of our staff estimator/project managers had extensive experience in tilt-up before he joined our firm. He was experienced enough to win the bid for us. Unfortunately, once COVID hit, he eventually came down with the ailment and is no longer able to work due to severe complications.  That leaves us with an upcoming job on the books with a firm start date and no one currently onboard who has the tilt-up chops to help get the job started. (We understand his counterpart during bid time is no longer with the GC, as well).

The project itself consists of a 10,000 square foot (SF) warehouse intended to store winery products and supplies located out in the wine country region. The structural frame consists of 30-foot-tall reinforced concrete tilt-up wall panels with an open-web steel joist roof (no concrete at roof level). The slab on grade is 6 inches thick, placed over 15-mil vapor barrier and 4 inches of drain rock, and reinforced with #4 bars at 16 inches each way. The nominal design compressive concrete strength is 3000 pounds per square inch (psi) at 28 days. Structural typical details indicate 2 inches of concrete cover below sawcut control joints at 1 1/2 inches in depth. There is a small mezzanine located inside the structure, which is supported by a small number of 6-inch square HSS (high strength steel) columns founded on spread footings.

The building footprint has an irregular shape, which follows a sharp bend in a local protected creek along two sides of the property.  There is a steep, sloped, 75-foot wide easement that separates the building edge from the bend in the creek bed. No construction vehicles, material storage, or other construction activities are allowed in or on the 75-foot easement.  In other words, there is no available construction access on two sides of the project. Inside the jobsite boundaries, there is virtually no laydown area available.

During the kickoff meeting, discussion ensued regarding jobsite access and logistical constraints.  The Owner advised that his office has been contacted by local building officials who reminded him that the environmental restrictions on encroachment--on or into the 75-ft creek easement zone--will be strictly enforced.

In addition, the structural engineer advised that driving forklifts or other equipment over the slab on grade or using the slab on grade as a platform for tilt-up panel erection (or structural steel erection cranes) will not be allowed. We had been proceeding with the assumption that we would be able to place the 10,000 SF slab on grade at one time, and then use the new slab as a casting bed for the tilt-up wall panels.  We also assumed our erection crane would be allowed to drive on the slab on grade.

The GC advised that a submittal containing our tilt-up panel logistics plan, including crane safety, panel erection, temporary panel bracing and so on will likely have to be approved by the local building official before we can start work, and suggested we get the submittal prepared as soon as possible.

We are wondering if the ASCC Hotline can offer any words of encouragement, and hopefully suggest some options to help us meet the challenges described above.  Please advise.

Answer: After reviewing the construction drawings for this tilt-up warehouse, we have the following observations and suggestions.

--The access constraints and jobsite geometry can easily be found on the contract drawings.  The 75-foot wide easement, for example, appears on multiple sheets. It seems likely that your estimator already had this handled with his counterpart at the GC during pre-bid discussions.  Suggest trying to track that down with a call to the GC.

--The compressive strength of the slab on grade (3000 psi) seems to be on the "low" side, which may be driving the engineer's objections to driving equipment on the slab. Since there are ways to strengthen concrete slabs, you may consider a cost-sharing arrangement with the steel erector, whereby costs to re-engineer the slab would be split. Possible options might range from adjusting the mix proportions (e.g. add cement) or perhaps thickening the slab.  Another option might be to call a meeting with the structural engineer, the GC, and the steel erector and ask if a slab analysis/redesign could be handled by his office in-house.

Any costs could be covered by a mutually agreed backcharge. 

--It may be feasible for you to place the slab in two placements.  Panels would be cast on the new slab, while the crane could stage on the adjacent subgrade and erect the panels from there.

--We noticed that there are details that show embedded plates that are shop welded to steel channel sections that serve as ledgers for follow-on framing work at the roof level.  If these assemblies are cast in as designed, you will not be able to stack any tilt-up panels, since the channels protrude past the face of wall.  The assemblies will have to be redesigned such that the ledger channels can be field-welded in place to the embedded portion (placed flush with face of wall) after the walls are erected.

Update: The Hotline was just informed that a meeting was held among the Owner, the building officials, and the fire marshal.  It seems likely now that the Owner will have to provide a temporary fire lane along the creek sides of the building. It appears the contractors will be able to use this sanctioned "encroachment" for erection purposes.  It may also be possible that the fire lane will have to be made permanent before the project is turned over. If true, this could help solve most--if not all--of your logistics issues.

Note: A pat on the back (and a tip of the hat) goes out to ASCC Technical Committee member Jeremiah Mistele of PROCON, who helped with this Hotline call.