new two-story, 50,000 ft2 (4600 m2) commercial officebuilding that captured the essence of Neo-FrenchClassical architecture while staying within a fixed marketrate cost for this type of structure. The precasterwas brought in at an early design stage to work withthe architect and ownerto develop a verydetailed, typical selfsupportingwall panel10 ft (3 m) wide x34 ft (10.4 m) high.Great care was takento build a mold thatcould be used overand over again, butwould give the projecta wonderful senseof detail and richness(Fig. 2.1.5[b] and [c]).Because of the repetitivenature of the panelsand their ease ofinstallation, the precastconcrete systemended up costing lessthan brick and steelconstruction. The result of using this architectural precastconcrete system was a beautifully detailed ClassA office building that was 90% leased within fourmonths.Coordinated design, complete dimensioning, and clearspecifications (see Chapter 6) are also important factors inobtaining optimum quality and economy using architecturalprecast concrete. In the preparation of the contractdocuments, the selection and description of materialsand performance requirements should be clearly stated.They should not be left open to variable interpretations,however nor should they be overly restrictive.The contract documents should make referenceto the PCI Manual for Quality Control for Plants andProduction of Architectural Precast Concrete Products(MNL-117), which includes Category A-1 certificationof the production facility, as the industry guideline forproduction of architectural precast concrete elements.Exceptions to this standard or specific requirementsshould be clearly set forth in the contract documents.2.2 DESIGN ECONOMYUnderstanding architectural precast costs is essentialto designing affordable faades that enhance theoverall building design while meeting the owners budget.Understanding the architectural precast concretemanufacturing process can help achieve design goalsand control costs.During a projects conceptual stage, the designer hasmany variables to consider that affect precast concretecost. A local precaster can assist with preliminary designand budget estimating early in the projects designphase. Piece size and repetition typically have the mostsignificant cost impacts. In addition, material selection,textures, surface geometry, cross-section, erection details,

jobsite access conditions, and connections canaffect cost. The custom, sculptured designs that arepossible with precast concrete may be achieved withina limited budget by selecting appropriate aggregatesand textures combined with repetitive units and efficientproduction and erection details. Input from theprecaster can be beneficial in developing options forcreating an economical design that also satisfies thedesigners aesthetic requirements.During preliminary design, a precast concrete projectcan be preliminarly budgeted on a square-foot (m2) basis.Although this provides a starting point, it is recommendedthat the designer seek additional estimatingassistance from a precaster. Working with a precasteron a specific project will help determine a final budgetthat is more accurate than a ballpark price per squarefoot (m2). A cost per square foot (m2) can be misleadingto general contractors and architects becausesquare foot (m2) quantities are calculated differentlyfrom precaster to precaster depending on the take-offprocedures. Also, total work scope requirements suchas site restrictions, work scope inclusions, and detailmanufacturing requirements are initially unknown.Budget pricing from local precasters, submitted inwriting and including assumptions, will aid design effortsfrom schematic design through final contract documents.As a project evolves from preliminary sketchesthrough working drawings, the precaster(s) should beinformed of all changes.Pricing accuracy depends on the information providedto the precasters estimator. This discussion on designeconomy uses square foot (m2) prices to describe a designersprecast concrete options. All prices are for relativecomparison only and should not be used to makedecisions for individual projects.The design and detailing of the precast concrete unitsshould reflect good production concepts. Consultationwith a precaster at an early stage will be helpful. Thedesigner needs to define the shape of the units andtheir appearance.2.2.1 RepetitionA key element to cost-effective production is minimizingthe number of molds and mold changes, and maximizingthe number of castings from each mold, particularlyif the molds have shape. Efficiency and economyare achieved by making it possible for similar, if notidentical, shapes to be produced from the same basic(master) mold, and by minimizing the time required todisassemble a mold and reassemble it for the manufactureof the next piece. Figure 2.2.1(a) shows the mastermold for the production of the arch member panels forthe project in Fig. 3.3.18(a), page 121. The largest segmentof the arch is shown in Fig. 2.2.1(b).Careful planning is necessary to achieve good repetitionin the design without sacrificing design freedom.For example, many design variations may be developedby incorporating two basic architectural paneltypes (spandrel panels and floor-to-floor panels with