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Estimating Waste

Estimating Waste. Week 3 CTC-415. What is waste. Waste is material that needs to be supplied but may not be used All material items except steel beams and columns have waste Needs to be minimized. Concrete & aggregate quantities. Concrete work

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Estimating Waste

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  1. Estimating Waste Week 3 CTC-415

  2. What is waste • Waste is material that needs to be supplied but may not be used • All material items except steel beams and columns have waste • Needs to be minimized

  3. Concrete & aggregate quantities • Concrete work • Some can be precisely estimated – columns, walls • Some cannot – footers, sidewalks, anything bearing on ground • Concrete batched by weight not cubic yards • May have variances due to sand and aggregate density • Assume 3 – 5% waste for variances

  4. Concrete & aggregate quantities • Asphalt • Batched by weight • Assumes uniform weight for sand, aggregate and filler • Also assumes existing grade is precise and accurate • Assumes compaction is correct • 5 – 10% waste

  5. Concrete & aggregate quantities • Sand and Gravel • Sold by weight • Based on bank volumes at pit • Based on loose volumes on truck • Based on compacted volumes at job site • Need to know swell and shrinkage of soil • Can be 25 – 40% changes • Need to know moisture content of soil

  6. Masonry • Can count block needed • Need to account for breakage • Especially if cutting block/brick to size • 5 – 20 % depending on cutting • Need to add in corners, lintels, special shapes • 5% waste

  7. Rebar • Waste comes from need to cut pieces to length • Rebar comes in lengths up to 40’ • Overlap – 30 – 40 diameters at joints • Are you buying or bending pieces? • Storage area • Mud, security, covered? will determine extra rebar needed • Caps, ties, shoes, etc – buy by the case

  8. Steel • No waste when doing steel quantities. • Beams and columns are fabricated to specs • Will have extra bolts, rivets

  9. Wood • 2x stock • Count all 2x stock as 8’ min pieces • 5 – 10% extra for blocking, bad pieces • Sheathing • Do not take out doors or windows when determining quantity • Add 5% waste • Nails & screws • Buy by the 25 – 50 # box

  10. Roof • Tar paper , roll roofing • Want full sheets across roof if possible • How many full sheets/ roll • Shingles • Measure roof divide by 100sf gives # of squares • Add 10% waste • Metal • Comes in sheets • Count full sheets needed

  11. Other Exterior • Siding • Figure square footage – excluding windows and doors • Add 5 – 10% waste • Trim • 5% waste

  12. Interior • Sheetrock • Want minimal seams 10% waste • Plumbing • Buy pipe in 10’ lengths • Minimize joints – buy in contractor packs • 5 – 10 % waste • Heating • Air – minimal waste in large ducts • Baseboard buy by length

  13. Interior • Electrical • Buy wire in boxes - 250’ lengths • charge by the box – 5% waste • Wire nuts – buy by the box • Countertop • Linoleum – by the sheet • Granite, corian – cut to fit – no waste

  14. Interior • Trim • 5 -20% waste depending on finish • Flooring • Carpet & Linoleum • Can have large waste factor depending on room size and carpet direction • Hardwood, tiles – 5%waste

  15. Exact Counts • Doors & Windows • Plumbing Fixtures • Appliances • Sinks, toilets • Light fixtures, vents, fans, outlets, switches • cabinets

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