Glossary of Terms

Cast-in-place Concrete (a/k/a in situ): Cast-in-place concrete is transported in an unhardened state, known as ready-mixed concrete, and placed in forms. Ready mixed concrete is proportioned and mixed off the project site and delivered to the site, typically in an agitating truck (but can also be delivered in a non-agitating truck). Cast-in-place concrete is the material of choice for slab-on-grade and foundations because of its long-term durability and structural support. It is also used in all types of buildings for either structural support as beams and columns, as well as for floors, walls, and roofs.

Conventional Reinforcement: Conventional Reinforcement is a method of reinforcing prestressed concrete whereby reinforcing steel is utilized to provide additional support for the concrete and in which the concrete bonds to the reinforcing steel as it cures providing almost immediate crack control but requiring greater thickness to achieve the same strength as post-tensioned concrete, which, in turn, results in greater cost.

Design-Bid-Build Basis: Design-Bid-Build is the traditional project delivery method in which there are separate contracts with separate entities for the design and construction of a project. In the design phase the owner retains an architect to design and produce the technical drawings that the general contractor will bid and will be utilized to construct the project. In the bid phase, the general contractor obtains the drawings and then distributes them to multiple sub-contractors for bids on the sub-components of the project. Sub-components include items such as the concrete work, structural steel frame, electrical systems, and landscaping. The general contractor is essentially a management firm expert in managing the construction process and daily activity on a construction site. After the project cost has been agreed to, the applicable documents are revised, necessary approvals received form all jurisdictional authorities, final construction documents are approved and the building or construction phase can begin.

Design-Build Basis: The Design-Build process is a construction project delivery system used to reduce the project delivery time by overlapping the design phase and construction phase of a project. Design-Build focuses on interweaving the design, permit, and construction schedules in order to capture the time lost in a traditional Design-Bid-Build environment. This does not shorten the time it takes to complete the individual tasks of creating drawings, acquiring building permits, or actually constructing the building. Instead, a quality Design-Build firm will bring together design and construction professionals in a collaborative context to complete these tasks at the same time. Using this mechanism, Design-Build represents a risk management strategy that places a premium on delivering the project sooner with less of a focus on delivering the project at a lower construction cost.

Elevated (podium or platform) Structures: Elevated structures (podium or platform) elevate timber structures above the ground plane. These structures require minimal excavation, preserve natural features and existing drainage patterns of a site, and are particularly useful when the terrain involves steep slopes and in areas where there is periodic flooding. Where soil is unstable or insufficient to bear the proper load, a deeper foundation for the elevated slab may be required with the two principal types of deep foundations being pile foundations and caisson foundations. The determination of whether a slab-on-grade or elevated structure should be employed requires the input of a structural engineer in conjunction with an assessment of project need. Use of elevated structures is of particular importance in addressing parking needs at a site.  By elevating the parking, the developer can eliminate the need for surface parking and allow for the creation of more living units and greater revenue generation. In addition, where flood plain issues exist, elevating the deck allows for building above the flood plain line.

Parking Structures: For decades, cast-in-place concrete parking structures have been successfully constructed and utilized throughout North America. In most cases, post-tensioned structural systems are utilized after economic analysis and studies of the cost savings. The cast-in-place concrete structural system most commonly used for parking structures is a one-way slab and beam. Most parking structures are examples of the beam-and-slab structural system, though two-way flat plates and flat slabs are also used. Parking structures can also be constructed from pre-cast concrete which can be a very cost-effective way to build durable and attractive garage products.

Post-tensioning: Post-tensioning is a technique for concrete reinforcement using flexible cables that are tensioned after the concrete hardens thereby placing the concrete in compression. Cables are tensioned after the concrete is placed after such time as will produce the desired strength of the concrete. Post-tensioning results in visible curing, non-structural cracks that are resistant to shrinkage, but is generally viewed as a superior method of avoiding structural cracking.  Post-tensioning has been used for many decades in bridges, elevated slabs (parking garages and residential or commercial buildings), residential foundations, walls, and columns. The use of post-tensioning can result in thinner concrete sections, longer spans between supports, stiffer walls to resist lateral loads, and stiffer foundations to resist the effects of shrinking and swelling soils. The additional advantage of putting the concrete into compression can be used to construct slabs and walls that have fewer visible cracks that can allow the passage of moisture and termites. The reinforcing for post-tensioning consists of very high strength steel strands or bars. Typically, strands are used in horizontal applications like foundations, slabs, beams, and bridges; and bars are used in vertical applications like walls and columns. The prestressing steel is housed in a sheathing or duct to allow it move as the tensioning force is applied after the concrete cures. The steel stretches as it is tensioned, and it is locked into place using an anchoring component that forms a mechanical connection and keeps the force in the strand for the life of the structure.

Pre-cast Concrete: Pre-cast concrete is an ancient type of construction material made with concrete cast in a reusable mold or "form" and cured in a controlled environment, then transported to the construction site and lifted into place. Uses for pre-cast technology include a variety of architectural applications including free-standing walls used for landscaping, soundproofing and security walls. Pre-cast architectural panels are also used to clad all or part of a building facade. Storm-water drainage, water and sewage pipes and tunnels make use of pre-cast concrete units.

Slab-on-Grade: Slab-on-grade foundations are a building engineering practice whereby the concrete slab that is to serve as the foundation for the structure is formed by pouring the foundation directly onto the ground,. This type of construction was originally seen most frequently in warmer climates, where ground freezing and thawing was less of a concern and where there is no need for heat ducting underneath the floor, but has long since become a mainstay technique in all climates. Slab-on-grade foundations are commonly used in areas with expansive clay soil. While elevated structural slabs actually perform better on expansive clays, it is generally accepted by the engineering community that slab-on-grade foundations offer the greatest cost-to-performance ratio for tract and semi-custom homes.

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