Perfecting A Common Construction Strategy
Multi-Story Building Stick Frame Wood over Concrete Podium Lessons Learned
A well proven construction strategy for multi-story buildings, podium construction offers long-term durability, low maintenance and fast-track site erection.
Providing cost efficiencies in labor and materials, these types of buildings offer greater design flexibility, less environmental impact and a more efficient construction process.
The following is a step-by-step guide for successfully building a stick frame wood over a concrete podium multi-story building, on time and on budget.
1) Constructability Review
Prior to ground breaking, if not sooner, the superintendent carefully reviews the architectural, structural and civil engineers plans, checking for areas which cannot be built as designed, or that could become issues down the road. This review may include dimensions/layout, framing methods, code constraints, material usage and any conflicting designs between the architect and engineers.
2) Framing Book
The completion of a framing book helps the framers and inspectors easily access information on the framing throughout the building. This should include: floor and roof truss layout; door/window rough openings; headers; jack/king studs; baring walls; shear walls; bracing for cabinets, bathroom accessories/ADA handrails, TV mounts, shelving and hold downs/uplifts.
The book should identify the location and sizes of each item with unit plans, floor plans and engineer- required structural drawings, along with relevant shop drawings/submittals and Requests for Information (RFIs).
The team should review the structure’s construction types above the roof deck, i.e., elevator overrun, stair overrun, etc., and consider questions such as whether the framing needs to be fire treated and whether the interior underside of the roof needs a fire rating.
3) Assurance & Quality Control
For both the podium pre-pour and wood framing, there are a number of important quality control measures which should be taken.
Regarding the former, the carpenter should lay out all the walls on concrete plywood deck. Then the mechanical, electrical and plumbing (MEP) engineers can use the wall layout for sleeving.
The embeds/sleeves/openings must then be verified, located and installed correctly. This includes the framing hold down system, guardrail/handrail and brick relief angle embeds; fire suppression, HVAC, plumbing and electrical sleeves; and floor boxes. The trash chute opening should be accurately located and installed, as should the future rated chase shaft opening.
Quality assurance for the wood framing should involve checking the headers; shear/bearing/exterior wall studs; window rough openings and ensuring the correct heights; checking the door rough openings; ensuring the jack/king studs are properly located and sized; checking that the sheathing and bracing are installed as required; and that the hold downs/uplifts are per the plans/RFIs.
Other areas to review are the MEP rough in for fire stopping and if there are balconies, making sure the framer leaves adequate space for the steel sub to install balcony steel and make welded connections.
Once the building is built, the project team must pass a number of inspections.
Third party inspections include:
- Concrete/concrete masonry unit – soil/compaction, rebar, post-tension slab cables installation/tensioning and concrete/grout testing
- Metal –welding joints at the stairs, embeds and structural steel
- Framing – shear wall sheathing, exterior sheathing and nail patterns
City/county inspections are performed for:
- Framing –headers, jack/king studs, floor trusses, uplifts/hold downs, fire caulking, shear wall framing and bearing wall framing
- MEP rough-in and fire sprinkler inspections are completed before the insulation and drywall is installed.
- Insulation – netting/blown in, rock wool and batt insulation, channel installation, fire-rated walls, chases and ceilings
- Drywall – channel installation, fire-rated walls, chases and ceilings
Inspections for the building envelope may include mockup Inspection:
- Window/exterior door installation
- Flashing and sealing
- Water proofing
- EIFS – insulation, installation and joints
- Masonry veneer
- Metal panels- installation and caulk/sealing
If at all possible, it’s important to start the county inspection process for the framing and MEP/sprinkler as early as possible. Inspectors may only be able to spend a limited amount of time per day doing the inspections, which then spreads out the process over a longer period. This then makes it very difficult to continue with insulation and drywall in a timely manner.
Make sure to stay on top of corrective work called out in the RFIs, observations and architectural reviews. If necessary, bring these issues to the subcontractors’ attention. It’s important that these corrections are made in a timely manner and if needed, seek direction from the architect or engineer to approve corrective modifications.
Another key best practice is taking the concrete pre-pour checklist seriously. Once it’s poured, it costs thousands of dollars each day to scan the concrete for rebar and post-tension cables. This can be largely avoided by taking pictures with tape measure during the pre-pour, noting the concrete clear cover and location of the photo.
Coordinate the drywall and finish schedule with the subcontractors. This includes the scheduling of MEP rough ins and drywall installation.
A possible time saving/value engineering option is to pitch the roof structure with trusses in lieu of tapered insulation as it requires a longer lead time and is more expensive. Then the roof trusses can be fully insulated with the architect’s approval.
Ultimately, bringing in a skilled and experienced contractor is the best assurance for a successful multi-story building stick frame wood over concrete podium build.
Contact Summit Design + Build to see how we can support your next multi-family project.