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Estimating Demolition: Takeoff by Material, Production Rates & Disposal

Estimating Demolition: Takeoff by Material, Production Rates & Disposal

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Alright, Estimating Demolition: Takeoff by Material, Production Rates & Disposal. Don't let the plain title fool you. Here's the part that actually matters on the job: A demolition estimate is built from tons and cubic yards by material stream, each with its own production rate, haul, and disposal cost or scrap credit, and the bid lives or dies on disposal and on what the contract says about the unknowns. Learn it well and you stop guessing by the square foot and start knowing, which is the difference between a demolition company that grows and one that wins the jobs it should have lost.

Demolition has no material to buy, so the estimate is labor, equipment, hauling, disposal, abatement, and risk. The intro mentioned estimating by material; this lesson shows how it is done.

The takeoff is by material, not by square foot

Walk the building with the drawings and a notebook and quantify each stream separately: concrete (slabs, foundations, walls, by thickness), masonry, structural steel and metal deck, wood framing, roofing, drywall and plaster, glass, flooring, mechanical and electrical equipment, fixtures, and mixed C&D. For each, note the condition that affects handling: rebar density in the concrete, paint on the steel, whether the wood is clean or treated, whether the roofing is one layer or four. Square-foot and cubic-foot unit prices from past jobs are a sanity check at the end, never the estimate. Two buildings with the same footprint, one a wood-frame office and one a concrete parking structure, differ by an order of magnitude in tons.

Converting volume to weight and truckloads

Disposal is priced by the ton or by the load, so the takeoff converts:

Labor and equipment production

Production is estimated per task in crew-hours or machine-hours: interior strip-out per thousand square feet by a crew of a given size, slab breaking per hundred square feet by a breaker or a hydraulic hammer, structure removal per floor by a high-reach or an excavator with a processor, concrete processing and rebar separation per ton, loading per load. Each company builds its own rates from its own timesheets, and the rate on a bid is adjusted for the conditions the walk-through found: access, floor height, how far debris has to travel, whether a machine can get inside, hours restrictions, winter. The equipment spread is sized so processing keeps pace with the trucks, because an excavator waiting for a truck and a truck waiting for an excavator are both costs the estimate carries.

Disposal, recycling credit, and hauling

Every stream has a destination and a price that changes with the region and the month, so the estimator calls before bidding:

Hazmat, unknowns, and what the contract says

Abatement is priced from the survey quantities as a separate line or a subcontract quote, and a contract that gives the demolition contractor a survey with areas not accessed should also give them an allowance or unit prices for material found later. The estimate names its assumptions: the survey it relied on, that utilities will be disconnected by others by a date, that the building is empty of contents, that the slab and foundations are included or excluded to a depth, that backfill and grading are or are not in scope, that salvage rights belong to the contractor or the owner, and that unknown conditions, buried tanks, contaminated soil, a second slab under the first, are handled by a change under a differing site conditions clause. A bid without written assumptions is a bid that absorbs every surprise.

Putting the bid together

Direct costs by task and stream, plus mobilization and demobilization, fencing and protection, dust and vibration controls, permits and utility disconnect fees, temporary utilities, supervision, insurance including pollution liability, and the schedule-driven general conditions. Then markup for overhead and profit, and a contingency sized to the age of the building and the quality of the survey. Compare the total to the company's historical unit prices per square foot and per cubic foot of building for the same type, and if they disagree, find out why before the bid goes in.

Going Deeper (Intermediate)

Cash flow matters in demolition because disposal is paid as you go and the scrap check arrives after the steel ships. The schedule of values puts mobilization and abatement early and the estimator knows which streams cost money the week they leave the site. On selective demolition, the estimate also carries the cost of protection, containment, after-hours premiums, and elevator time, which can exceed the labor to remove the work.

Advanced / Pro-Level

Pros keep a database of actual tons by building type and actual production by task, reconciled against weight tickets and timesheets after every job, so the next estimate is built on the last one's truth. They walk the building thinking about asset recovery, the equipment, motors, and architectural pieces that can be sold rather than hauled, and about the sequence that pulls the copper before the building is open to the street. They price the risk of the survey, not just its findings, and they decline jobs where the owner will not provide one.

Practice Challenge

A contractor is pricing total demolition of a single-story 30,000 square foot masonry warehouse with a 6-inch slab, a steel roof structure, and an asbestos survey that shows roofing felts and floor tile mastic. The owner wants a lump sum with no allowances. What does the estimator do? (Answer: take off the streams separately, slab at about 740 tons of concrete for the floor alone plus foundations, masonry by the wall area and thickness, steel from the roof framing as a scrap credit, roofing and mixed debris to the landfill; price the abatement from the survey quantities by a licensed sub; call the recycler, landfill, and scrap yard for current rates and count loads against truck weight limits; and write the assumptions into the bid, naming the survey relied on, the slab depth, the utility disconnect by others, and a differing-site-conditions clause for tanks or contaminated soil, because a lump sum with no written assumptions makes the contractor the insurer of the unknowns.)

In Practice

An estimator who prices the warehouse in tons and loads, calls the yards, and writes the assumptions into the bid hits the number and gets paid for the surprise. One who multiplies the square footage by last year's unit price finds the second slab under the first with no way to bill it.

Common Mistakes to Avoid

Takeaway: A demolition estimate is built from tons and cubic yards by material stream, each with its own production rate, haul, and disposal cost or scrap credit, and the bid lives or dies on disposal and on what the contract says about the unknowns.

Educational content only — not structural engineering, a demolition plan, an engineering survey, or hazardous-materials advice, and not a substitute for hands-on training, a competent person, or a licensed engineer, asbestos inspector, or abatement contractor. Follow OSHA 29 CFR 1926 Subpart T and the silica, asbestos, and lead standards, the EPA asbestos NESHAP and your state's hazardous-materials rules, the building and fire codes as adopted in your jurisdiction, the engineer's temporary-support design for your project, and the manufacturer's instructions for every shore, tool, and machine you use.

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