Where a podium slab meets a retail storefront, the waterproofing detail carries the building's warranty. Water that gets into a transfer slab shows up as efflorescence in the garage below, corrosion in the post-tensioning, and a claim two years after turnover. Mixed-use and multifamily buildings concentrate that risk, because residential, retail and parking are stacked on one structure with one roof and one set of penetrations. We build the parts of these projects that behave like industrial work, and we coordinate the rest.
Our scope on a multifamily or mixed-use project typically includes site demolition and earthwork, utilities and fire water, deep foundations, below-grade structure and podium slabs, parking decks, and the site concrete and paving around the building. Wood- or steel-framed residential levels above the podium are built by framing specialists under our management or by the owner's separate contract, depending on the delivery method.
Developers and lenders who finance these projects care about three numbers: the foundation and podium cost, the schedule to topping out, and the date the first units are certificated. We structure our proposals so each one is visible and can be tracked.
Transit-oriented and infill districts around Denver
Mixed-use development in the metro clusters around rail stations and former industrial or institutional land. The former Stapleton International Airport site covers about 4,700 acres and is projected to create about 13,000 jobs and about 1,100 acres of new parks and open space at build-out; the redevelopment is guided by a plan approved in 1995. In Englewood, CityCenter is a 55-acre mixed-use district bounded by U.S. 85, Elati Street, Hampden Avenue (US 285) and Floyd Avenue, and it was the first transit-oriented development in the Front Range region.
Northeast of downtown, Gateway Landing is a 34-acre mixed-use development in Denver's Green Valley Ranch by Equity Ventures Commercial Development and Wall Development Group, with residential units at the northeast quadrant of Green Valley Ranch and Peña boulevards. RTD's N Line opened September 21, 2020, with three stations in Thornton (Original Thornton/88th, Thornton Crossroads/104th, and Eastlake/124th, the northern terminus). Stations like those draw residential projects with ground-floor retail and structured parking.
Legacy soils, vapor and podium foundations
Many infill sites sit on formerly industrial ground. Neighborhood activism in Globeville and Elyria-Swansea won a 1994 settlement with ASARCO that funded soil cleanup, a sign of the legacy smelter contamination that due diligence should check near north Denver's industrial areas. Before a residential building goes on such a site, an environmental assessment, soil management plan and often a vapor mitigation system under the slab are part of the scope. We have these items in the estimate from the start, not as a surprise.
Podium buildings place heavy, concentrated column loads on foundations. Depending on the soils, deep foundations and piers or a mat foundation with ground improvement may be the right solution, and the choice is settled with the geotechnical engineer before the podium layout is final. On sites with existing slabs, basements or old utilities, demolition and slab replacement clears the ground and records what was found.
Residential, retail and parking on one structure
Each use in a mixed-use building has different requirements. Residential floors need acoustic separation, balconies, egress and unit-level mechanical systems. Ground-floor retail needs taller floor-to-floor heights, grease exhaust routes, loading and trash. Parking needs ramps, ventilation and sprinklers, which we cover under parking structure. The structural grid is a compromise among all three, and the earlier it is set, the fewer transfers are needed.
Commercial space at the base follows the practices described on our retail shopping center page, with the added constraint that the shell sits under residential floors. Mechanical and plumbing risers pass through retail and parking, so we coordinate their routes before concrete is poured. The result is fewer core drills through post-tensioned slabs and a cleaner overhead in the retail spaces.
Where the money goes before the first apartment
On a podium project, the price before the residential levels begin is substantial: demolition, mass grading, utilities, shoring and excavation for below-grade parking, foundations, the podium slab and the waterproofing. That figure moves with soil conditions, groundwater, parking count and the amount of rock or old structure removed. We price these as unit costs with ranges so the developer can see sensitivity to the geotechnical findings.
Utility connections and off-site improvements are frequently underestimated. Water and sewer extensions, fire hydrants, street frontage, and sometimes undergrounding of overhead electric run through an adjacent right of way and require permits and inspections. The metals and heavy industry page describes the rail and heavy-utility conditions we plan around, and the same thinking applies to infill sites beside active rail corridors or industrial neighbors.
Sequencing the podium so framing can start on time
The critical path in a mixed-use building runs through the podium: excavation, foundations, below-grade structure, waterproofing, podium slab cure and inspection. Residential framers cannot start until the podium is released, and each week of delay costs the developer interest on the whole loan. We schedule the podium with sequencing by zones, so framing can start on the first completed zone while the rest of the slab is being placed.
Weather windows affect waterproofing, concrete placement and framing. Winter placement needs blankets or enclosures, and a wood-framed building must be protected from rain during construction. We plan temporary protection and drainage, monitor moisture in framing members before enclosure and sequence interior work to follow the weather-tight milestone. Completed floors are turned over to the owner in sequence to allow early leasing.
Start with the podium
Send the site, the unit and parking count and any environmental reports. We will return a scope for the below-grade and podium work with the unknowns priced as ranges.
Common Questions
What is the biggest cost risk on a podium building?
Below-grade conditions: groundwater, rock, contaminated soil or old foundations that were not found in early borings. We recommend enough geotechnical borings to see the footprint, a phase one environmental review and a contingency tied to the findings. The risk is much smaller when it is investigated before the budget is set.
How is post-tensioning coordinated with mechanical and plumbing?
By locating every penetration before the tendons are laid out. We use a coordinated drawing with sleeves and blockouts and scan the slab before any later drilling. Core drilling through a post-tensioned slab without a scan is a safety and structural hazard.
Can residential framing start before the whole podium is finished?
Yes, in zones. Once a zone of the podium slab has cured, been waterproofed and inspected, framers can begin there while the remaining zones are placed. The sequence needs temporary protection of exposed slab edges and clear separation between the two crews.
What should a developer know about vapor mitigation?
On sites with possible volatile contamination, a vapor barrier and sub-slab venting system may be required under the building. It is installed before the slab, tested and often inspected by the environmental consultant. Including it in the foundation scope avoids delays at slab placement.
Do you build the whole building or only the structure and site?
It depends on the delivery method. We can manage the full building with specialist subcontractors for framing and finishes, or we can build the below-grade, podium, site and utilities scope under a separate contract with the developer's residential builder. We will say which arrangement fits the project.