Estimating Waste Week 3 CTC415 What is 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 – 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 aggregate density • Assume 3 – 5% waste for variances

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

Concrete & aggregate quantities • Sand 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

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

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

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

Wood • 2 x stock – Count all 2 x 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

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

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

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

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

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

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