It’s more than adding and subtracting.

 Before bidding, the site should be examined for the following:  Distance from the office  Site conditions  Site access  Soil data and groundwater  Security and traffic needs  Adjacent structures  Possible contamination  Water, telephone, and electricity service  Obstructions  Parking and storage  Debris disposal  Local weather patterns  Local labor and sub-trades  Local regulations

 Materials are purchased in bulk and often long before they are needed, in order to keep down costs.  Estimators use basic math (counting), algebra (perimeter), plane geometry (area), and solid geometry (volume).  There exist basic formulae for many typical applications.

 You have to estimate the number of bricks for a wall that measures 15 feet tall and 84 feet long.  Standard bricks are estimated at 6.67 bricks per square foot of wall area (add 5% waste).  Mortar is estimated at 7.2 cubic feet per 100 square feet of wall area (add 40% waste).  How much of each do you need?  1260 ft 2 x 6.67 = 8404 x 1.05 = 8824 bricks  1260 ft 2 ÷ 100 x 7.2 ft 3 = 90 ft 3 x 1.4 = 127 ft 3

 Cinder blocks are estimated at 11 blocks per 10 ft 2 (add 10% waste).  Mortar for block walls is estimated at 2.4 ft 3 per 100 ft 2 of wall (add 30% waste).  Calculate the amount of block and mortar needed for 14 foot tall walls of a rectangular building (assume no windows and doors) that measures 37 feet by 52 feet.  Calculate the materials of adding a brick veneer to the entire façade.

 Footings and foundations require 3 dimensional calculations.  Their quantities are expressed in cubic yards.  1 cubic yard = 27 cubic feet.  To estimate the volume of this footing and foundation, first determine the square foot of the profile or cross-section of both.  Then, determine the perimeter.  Next, calculate the volume by multiplying the section area by the perimeter.  Finally, convert to cubic yards.

 Footing = 2.0 feet x 0.66 feet = 1.32 ft 2  Foundation = 2.0 feet x 0.66 feet = 1.32 ft 2  Section area = 1.32 ft ft 2 = 2.64 ft 2  Perimeter of building = 24 feet x 4 = 96 feet  2.64 ft 2 x 96 feet = ft3  ft 3 ÷ 27 ft 3 = 9.39 yards 3

 I Beams to span the short wall dimensions.  20 foot I Beams cost $ and must be placed 24” on center.  Corrugated steel panels are laid on the beams. They are 27” wide and 20’ long and cost $ each.  Concrete is then poured on top of the corrugated steel panels to tie the roof together as one item. Concrete will be poured to a depth of 3” and span the entire roof. Cost is $ per cubic yard.

 Insulated panels are then applied to the concrete. These panels measure 48” x 72” and cost $ each.  Asphalt is then spread over the insulated panels to make the roof watertight. The asphalt cost is $18.75 per square foot.  White stone is then spread over the asphalt to reflect sunlight. This stone costs $ per cubic yard. Spread 3” thick.  How would you set up the sheet for “Roofing”?