Construction Specifications: Open vs Closed

Specification Definition

• A specification is a definitive and complete statement within a contract that outlines precise construction methods.
• It combines words to describe a product's quality, manufacturing, project installation, and final appearance.
• Specifications are sourced from testing, product catalogs, governmental sources, and others.
• They should be clear, definite, comprehensive, and easily understood to prevent misunderstandings.
• Construction drawings indicate quantity, while construction specifications indicate quality to present the full scope of a project.

Types of Specifications

• Most specifications are categorized as either closed or open.
• Closed Specification: Restricts the selection to one material or process, or describes a material in such detail that only a single product can meet the criteria.
• Open Specification: Allows for a range of products deemed equal and acceptable, theoretically promoting competition among suppliers within equality parameters.

Other Specification Types

• Manufacturer's Specification: Typically written by professionals to sell their products by highlighting their best qualities, occasionally done by advertising agencies.
• Federal/Governmental Specifications: Serve as guides and master copies applicable to projects without listing manufacturer names to maintain open specifications.
• Commercial Specifications: May be either closed or open, depending on the owner's preference for a specific product, especially for private projects.
• Performance Specifications: Describe materials and acceptable installation methods, allowing contractors to select materials but limiting the architect's control, commonly used in private projects.

Styles of Specifications

• Streamlined Specifications: Shorter versions achieved by eliminating words, suitable for simple projects like small houses but potentially misleading if intent is lost.
• Preliminary Specifications: A preliminary listing of required materials or methods, used for guides, owner approval, or contractor requirements.
• Tabulation Specifications: Similar to preliminary specifications but used as a final specification.

The Uniform System or Master Format

• Standardized systems became necessary to improve communication between architects and builders.
• Previously, offices created their own specification systems, often lacking coordination.
• The Construction Specification Institute CSI formed in 1948 aimed to standardize specification writing.
• In 1963, the CSI published The CSI Format for Building Specifications, reducing the presentation to 16 basic divisions.

Three-Part Format (The Uniform System)

• Specification Outline: Groups work by divisions and sections.
• Filing System: Provides a method to file and retrieve manufacturers' literature under one of the 16 divisions.
• Cost Accounting Guide: Arranges construction cost items directly related to identical or similar items in a specification.

Sixteen Divisions (Format)

• Division 1: General Requirements
• Division 2: Site Work
• Division 3: Concrete
• Division 4: Masonry
• Division 5: Metals
• Division 6: Woods and Plastics
• Division 7: Thermal and Moisture Protection
• Division 8: Doors, Windows, and Glasses
• Division 9: Finishes
• Division 10: Specialties
• Division 11: Equipment
• Division 12: Furnishings
• Division 13: Special Construction
• Division 14: Conveying Systems
• Division 15: Mechanical
• Division 16: Electrical

Purpose of Estimating

• Estimating forecasts costs to compare a project with contract plans and specifications.
• Estimators determine direct costs accurately for materials, labor, and equipment.
• The bid price is determined by adding overhead, contingencies, and profit to these direct costs.

Two Tasks in Estimating

• Estimating determines the probable real cost.
• Estimating determines the probable real time to build the project.

Types of Estimates

• Approximate Estimates: Preliminary, conceptual, or budget estimates.
• Detailed Estimates: Final, definitive estimates.

Approximate Estimates

• These are done by multiplying square footage or meter by cost per unit.
• Experience and judgment are needed for a dependable approximate estimate.
• Approximate estimates evaluate design and present preliminary construction costs to the owner, but are insufficient for bidding.

Detailed Estimates

• Detailed estimates determine the costs of material, labor, equipment, subcontract work, overhead, and profit.
• Contractors prepare these from complete contract documents before bid submission.
• Detailed estimates are important to both owner and contractor as it represents the bid price.

Organization Estimates

• A comprehensive and well-defined organization of work items using CSI and WBS.
• Building Construction Projects: Contractors organize estimates following the CSI division of work based on 16 divisions as an industry standard.
• Heavy Engineering Construction Projects: Generally organized following the WBS format.

Site Works

• Volume of Earth/Backfill Required = Volume of Space x 1.25
• Volume = Area of Concrete Slab x Thickness of Fill

Concrete Works

• Cement Paste: Consists of cement and water, binding fine and coarse aggregates.
• Fine Aggregates: Natural sand of inert materials.
• Coarse Aggregates: Crushed rocks or gravel, sized 20mm – 30mmø (3/4" – 1 1/2"ø).
• Admixtures: Added during concrete preparation, specified by water-cement ratio, weight, compressive strength after 28 days, or fixed proportions.
• Class of Concrete depends on Class, Cement, Sand, Gravel, and Strength after 28 days

Allowance for Wastage

• 5% wastage: Columns, piers, beams, girders, reinforced concrete slabs, and walls.
• 10% wastage: Concrete slabs on fill, footings, wall footings, and concrete members without forms.

Slab (Method No.1 (Volume using Formulas))

• Computer volume of concrete into m³
• Add allowance for wastage
• Ascertain the class or mix
• Substitute the estimated concrete volume of C/V under appropriate class multiply by factors indicated

Formworks

• Temporary boarding shearing or molding produces the desired shape of concrete.
• Formworks must be watertight, strong, and rigid to sustain the concrete's weight.
• Greasing: Used with crude oil mixture with No.40 motor oil with ratio 1:3
• Intended to present water absorption in forms
• Framework that supports the column / beam or any concrete members

Reinforcement Bars

• Used to prevent crackling under force.
• Deformed plugs increase bond between concrete and steel preventing slippage.