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Constructing Podium Structures - A Comprehensive Guide

Constructing Podium Structures – A Comprehensive Guide

Since the 1960s, podium structures have dominated the construction scene due to their exceptional advantages. Owing to its superior qualities of extended durability, minimal upkeep requirements, and rapid on-site assembly, Podium takes precedence over the rest. These versatile construction materials find applications in various settings, from residential apartments and hostels to prisons, schools, and diverse commercial establishments.

That said, let us now dig into the details of what podium construction is and what you need to know about this widely used construction method. 

What exactly is Podium Construction?

It’s not just a “podium” in the name. Podium construction, also known as pedestal or platform construction, represents a unique building style with distinct horizontal divisions between an upper tower and a lower “podium.” Typically, this podium is constructed using steel or concrete, serving as a sturdy base for supporting multiple stories framed with wood on top. Commonly, podium configurations involve 4 to 5 stories designated for residential use, situated above commercial, retail, and parking spaces below.

Benefits of Podium Construction in North America

The prevalence of podium buildings in North America is on the rise, driven by the escalating costs of steel and concrete, coupled with the ever-increasing land rates. In response, contractors and developers are embracing wood designs that offer higher density and allow for additional rentable square footage compared to traditional garden-style apartments. This approach not only proves to be more cost-effective in terms of labor and materials but also provides design flexibility, reduces environmental impact, and accelerates construction timelines.

Key Advantages:

Innovative Wall Solutions 

Podium construction makes use of panelized walls to optimize both cost and time. These panels render better tightness tolerance, minimizing shrinkage caused by gaps. The inherent thermal and acoustic insulation properties of wood contribute to maintaining comfortable temperatures in residential and commercial spaces throughout the seasons. This natural insulation results in significant savings on monthly energy bills.

Moreover, wood paneling effortlessly blends with various interior decor elements and color schemes, creating a warm and inviting atmosphere when paired with suitable upholstery.

Ideal for Commercial Spaces 

Concrete podiums are well-suited for ground-floor retail and commercial spaces, giving away a distinct character to the residential areas above. The integration of both residential and commercial spaces within a single building appeal to tenants seeking the convenience of amenities, potentially enhancing the property’s overall value.

Integration of Amenities 

Podium-style buildings offer versatility in incorporating additional amenities such as gardens, outdoor pools, terraces, or extra parking spaces. Some jurisdictions permit up to two above-grade stories for construction on a seven-story building, allowing developers to combine concrete construction for two or three stories with wooden construction supported by the concrete podium for the remaining floors.

Before commencement, collaboration with your team is essential to understand the possibilities of the decision.

Emphasis on Sustainability 

Wood, as a naturally growing, renewable, biodegradable, recyclable, and non-toxic material, emerges as an environmentally friendly choice for construction. In contrast, concrete stands as the fourth-largest source of carbon dioxide emissions in the United States.

While measures have been implemented to reduce carbon emissions in concrete production, wood holds a substantial advantage in terms of environmental friendliness. Construction with wood follows a carbon-negative process, aligning with the construction industry’s pursuit of a sustainable future.

Sturdy Structure 

Engineered beams utilized in podium construction ensure durability and strength for demanding applications, making podium-style buildings as sturdy as traditional concrete structures. The lightweight nature of an upper wooden podium proves advantageous in areas prone to high seismic activity, mitigating the impact of lateral design loads. Additionally, the inherent flexibility of wood contributes to a more forgiving and resilient construction material compared to concrete, providing optimal value without straining your budget.

Types of Podium Construction

Construction of multi-level wooden structures typically falls into the category of Type III and Type V, each further divided into A and B. These categories have distinct fire-resistance rating requirements, as outlined in the IBC for different wall construction types.

There are two prevalent podium design configurations:

  1. Multi-Family Podium Design:

In this building type, a solid concrete podium slab serves as both the structural floor and a transfer slab for the steel frame construction above. Typically situated above parking levels, these slabs play a crucial role in minimizing sound transmission and enhancing fire ratings.

  1. Single-Family Podium Design:

In the context of residential structures, the garage floor undergoes a transformation into a hollow core floor to expand the living space. The hollow core level serves as the podium slab, providing benefits such as decreased sound transmission, elevated fire ratings, and reduced vibrations. An added advantage is that the ceiling surface requires no removal and is ready for painting.

Podium Construction through a Code Lens

The International Building Code (IBC) provides clear distinctions for podium constructions, classifying them as two distinct structures superimposed on each other.

For instance, under construction Type III-A, a structure can ascend up to 4 stories or reach a height of 65 feet. In comparison, Type V-A permits a maximum of three stories or a height of 50 feet. The incorporation of the National Fire Protection Association (NFPA’s) sprinkler system grants developers an additional 20 feet in height or an extra floor.

IBC defines the finished grade of the exterior walls as the lowest point between the property line and the building, typically standing at 6 feet. Consequently, for structural considerations, the measurement of height commences from the initiation of the podium, even if it doesn’t align with the genuine architectural height.

In regions susceptible to seismic activity, the American Society of Civil Engineers (ASCE) mandates earthquake-resisting wood lateral systems for podium story buildings.

Local regulations governing podium-style constructions exhibit variations, making it imperative to thoroughly review them before initiating your podium construction project.

Construction Methods and Expenses of Podium Structures

Podium slabs serve as crucial components transferring loads from a wood or steel frame structure to the underlying columns and walls. These slabs are crafted using specific construction techniques to ensure alignment with the substructure. 

Noteworthy podium construction systems comprise of:

1. Stress-Equipped On-Site Pours

In this construction approach, concrete is cast on-site, emphasizing stress-equipped techniques. The simultaneous pouring of beams and slabs minimizes joints, addressing the need for consistent joint maintenance, such as the periodic replacement of joint sealants, which could lead to heightened long-term costs. This method is particularly well-suited for projects prioritizing durability and considering lifecycle costs.

Advantages of stress-equipped on-site pours for podium structures include:

– Easy customization of building footprints and framing shapes, as contractors can readily modify formwork on-site. 

– Improved light distribution due to the placement of beams at intervals of 20-24 feet rather than 5-6 feet.

2. Pre-Stressed Hollow-Core Construction

This podium construction method is widely favored for its swift construction pace and the provision of a secure working platform. Precast concrete, pre-stressed offsite, is transported to the construction location, offering flexibility for projects with limited sites or restrictions on post-tension tendon stressing. 

Advantages of pre-stressed hollow-core construction are:

– Integration of architectural design into exterior panels. 

– Lower initial construction expenditures due to early decision-making and minimized formwork requirements. 

– Weather-resilient construction, as precast components are produced indoors. 

– Expedited construction timelines, as precast elements are simply shipped to the site for assembly.

What to Consider When Construction a Podium-Style Structure

When working on your podium-design, keep the following factors in mind:

Wood Shrinkage

In constructions involving wood bearing partitions and walls supporting multiple floors and the roof, IBC mandates an analysis by the contractor to ensure that wood framing shrinkage won’t compromise the building’s structural integrity. This analysis should cover the mechanical, electrical, and plumbing systems, demonstrating that the roof system remains structurally unaffected for project approval. If issues arise, redesign the project to accommodate variations.

It is advisable to engage a reputable construction contractor as inadequate structural shrinkage management can lead to various building problems. Throughout construction, pay attention to considerations such as expansion allowance due to heat, non-wood firewall separations, piping, horizontal ducts, and cementitious floor toppings.

Secure Tie-Down Systems

For multi-story buildings, continuous tie-down systems offer advantages over conventional systems, boasting uplift capacities and easy installation. Despite being an in-wall system, it poses challenges in terms of workability.

Concrete-Wood Interface

Address the challenge of designing the interface between the lower podium slab and upper wood superstructure for seamless load transfer. Ensure podium slabs possess the appropriate design strength to resist axial force.

Constructability Considerations

During podium construction, focus on installing post-tension cast-in-place. This involves post-tension tendons, utilities, drainpipes, block-outs, rebar, additional steel at the top column, raised curbs, and embed plates.

Wood Species and Grade

Identify the wood species and grade to streamline construction, preventing limitations like local unavailability and cost concerns.

Flexible or Rigid Analysis

Employ flexible or semi-rigid diaphragm analysis to determine shear wall distribution. Classify a wooden diaphragm as flexible or semi-rigid using two distinct processes. While flexible analysis is straightforward, it may underestimate interior loading. In semi-rigid analysis, contractors utilize rigid building parts to lay out shear walls.

Two-Stage Design

Adopt a two-stage design by treating the upper wood-frame portion as a separate structure from the lower concrete portion. This approach provides an alternative to uniform seismic response design, reducing forces on the upper portion.

Framing Types

Platform framing, a common Type V wood framed structure, utilizes double top plates supporting joists. Another framing type is modified balloon framing, where floor framings hang off the double top plate, serving as an alternative platform.

Opt for Podium Design Solutions for Your Upcoming Construction Venture

The integration of wood into building structures is often perceived as a challenge to the dominance of concrete in the construction domain. However, the reality is quite the contrary. Podium construction ingeniously combines concrete, steel, and wood, paving the way for a thriving market that has been rapidly gaining traction in recent times – and this trend shows no signs of slowing down. Opting for a podium-design structure proves to be a wise choice, delivering both construction efficiency and cost-effectiveness.

When opting for a podium construction project, it is crucial to seek the assistance of a reputable and licensed general commercial contractor. This ensures not only a seamless consultation process but also guarantees optimal outcomes for your venture. Choose Arrant Construction for a construction approach that aligns with contemporary demands and industry trends.

FAQs

What is Podium Construction?

Podium construction combines steel or concrete with wood to create a unique building style featuring horizontal divisions between an upper tower and a lower “podium,” commonly used for residential and commercial spaces.

What key advantages does Podium Construction offer?

Podium construction uses panelized walls for efficiency, provides energy savings, and is ideal for commercial spaces, integrating amenities flawlessly.

Is Podium Construction sustainable?

Yes, wood construction in podiums is environmentally friendly, follows a carbon-negative process, and ensures a sturdy structure with engineered beams.

What are the varieties of Podium Construction?

Podium construction falls into Type III and Type V categories, with Multi-Family and Single-Family designs being common. Each type has distinct fire-resistance ratings.

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