Objectives of Elemental Estimation 1. To reveal the distribution of costs among the constituent element of the project. 2. To relate the cost of any constituent element to its importance as a part of the whole project. 3. To compare the cost of the same element in different projects. 4. To enable a determination of how costs could have been allocated to obtain a better project. 5. To obtain and use cost data for future projects.
Ratio Used for Elemental Estimation 1. Element quantity to base unit quantity 2. Element cost to total project cost
Sample Ratios in Building Element Estimates :Laboratory and office Building Design Efficiency Areas Ratios Area of exterior vertical cladding to floor area 0.8244 : 1 Area of windows to area of exterior vertical cladding 0.1156 : 1 Area of windows to gross floor area 0.0951 : 1 Area of roofing to gross floor area 0.5113 : 1 Area of partitions to gross floor area 0.9618 : 1 Area of internal doors to area of partitions 0.0724 : 1 Area of floor finish to floor area 1.0023 : 1 Area of ceiling finish to floor area 0.9369 : 1 Volume of building to gross floor area 11.9669 : 1
Building An Element CostFrom Unit Cost Data (Analysis) Element: 3a. Exterior cladding: roof finish Unit Quantity Cost* Cost 12.7-mm gypsum board 16,140 ft2 $ 0.85 $ 5,652 4-ply built-up roofing 16,140 ft2 1.26 21,980 75-mm rigid insulation 16,140 ft2 1.41 22,765 40-mm stone 1,305 tons 50.00 6,350 Expansion joints, including: Flashing and butyl membrane L.S. — 2,000 Flashing at parapet 490 m2 30.00 14,000 $73,447 *September 1981 cost level.
Substructure a. Normal Foundations. Footing to extend to 4 ft below average finish grade with finish grade at an average of 1 ft below top of foundation walls. Allow for footing size 2 ft 4 ft and foundation wall 10 in. wide and 5 ft high. b. Basement excavations and backfill. Not applicable. c. Special foundations. Not applicable.
Substructure a. Lowest-floor construction. Plain slab 6-in.-thick concrete, including 8-in. of crushed stone, mesh reinforcing, screed and steel trowel finish. b. Upper-floor construction. Steel frame, metal floor deck, joint formwork. c. Roof construction. Steel frame, including 1 -in.-deep galvanized metal deck.
Exterior Cladding a. Roof finish. Build-up roof system, including wood cants, nailers, flashings, and 2 in. of rigid insulation for low-rise building. b. Walls below ground floor. c. Walls above ground floor. 12-in. composite wall with 4-in. modular brick facing, vapor barrier, 6-mm metal stud, 4-mm batt insulation, metal furring, and drywall. d. Windows. Aluminum frames with baked enamel finish. Thermally broken with one operable vent and sealed tinted double glazing. e. Exterior doors and screens. Aluminum framing with baked enamel finish thermally broken, sealed double glazing.
Interior Partitions a. Permanent partitions. Metal stud partitions, 4-in. thick with a single layer of -in. drywall on both sides. 8-in. concrete block fire walls with metal furring and drywall either side. b. Movable partitions. c. Doors. Hollow-steel honeycombed doors in -in. frames, including hardware for residential buildings.
Vertical Movement a. Stairs. Metal pan stairs, 5 ft wide 10 ft rise with half landings, including precast terrazzo treads and landings and picket railings. b. Elevator and escalators. Not applicable.
Interior Finishes a. Floor finishes. Quarry tile in vestibule, ceramic tile in washrooms, and vinyl acetate tile elsewhere. b. Ceiling finishes. Acoustic tile throughout. c. Wall finishes. Tape, fill, and paint.
Fittings and Equipment a. Fittings and fixtures. Allowance to cover washroom accessories, signs, and floor mats ($200,000). b. Equipment. Not applicable.
Electrical a. Services. Complete electrical installation, including electric heating. b. Lighting and power. Lighting throughout. c. Systems. Not applicable.
Mechanical a. Plumbing and drains. Allowance for residential buildings. b. Fire protection. One head per 120 ft2 ($190/head). c. HVAC. Room top system, 0.0001 ton of cooling per square foot of gross floor area.
Overhead and Profit • Allowance for simple commercial projects with excellent market conditions.
Site Development a. General. Rough grade, spread imported topsoil, fine grade, and place sod. Roads and parking, including 6-in. of crushed stone base, 3 in. of double-layer asphalt, and precast concrete curbs. Walks and steps 4 ft wide, including 4 in. of crushed stone base, 5 in. of concrete, mesh and broom finish. Include a planting allowance for trees and shrubs (allowance $250,000). b. Mechanical and electrical. Site drainage and services to the building (allow $100,000). c. Alterations. Not applicable. d. Demolition. Not applicable.
Contingencies a. Design. Allow 6%. b. Escalation. Allow 2%. c. Construction. Allow 3%.
Estimate note: The total cost is within the range predicted by the preliminary estimate (19,000,000+25%)