How to Estimate Demolition Materials: Step by Step Guide

Estimating demolition materials means turning the area and the assemblies from your takeoff into a buy list of dumpsters, hauling, disposal fees, and the consumables that keep the demo safe and clean. Demolition has no product to install, but it has real material costs: the containers that leave the site, the fees at the landfill or recycler, the protection of what stays, and the dust and noise control that keeps the job from getting shut down.

What You Are Counting

A demolition material takeoff is six groups of materials and services stacked together. You count and measure the dumpsters and hauling by the load, the disposal and tipping fees by the ton or the CY, the recycling and salvage by the ton, the temporary shoring and protection by the SF or LF, the dust and noise control by the each or the LF, and the utility disconnections by the each. Each group is a separate line item because the hauler, the landfill, the recycler, and the protection supplier all quote separately.

Dumpsters are rented by the each, sized 10, 20, 30, and 40 CY, and hauled by the load. Disposal fees are charged by the ton at the landfill or transfer station, with a separate tipping fee per load. Recycling is quoted by the ton for clean wood, metal, and concrete, often at a lower rate than landfill. Temporary shoring is priced by the LF of wall or the SF of floor propped. Dust control is poly sheeting by the roll, zip walls by the each, and HEPA filters by the each. Utility disconnections are priced by the each, one per line capped and tagged.

Units and Waste Factors

Demolition waste factors are really volume to weight conversions and swell factors, and they are larger than for new work because demolished material fluffs up. A stud wall framed 16 in on center produces about 1 CY of debris per 25 SF of wall, and a drywall partition produces about 1 CY per 20 SF. Concrete broken out swells 1.5 times. The waste factor on dumpsters is 10 to 15 percent because the container never gets filled to the brim, and the hauler charges by the load regardless of how full it is.

The rule of thumb is to compute the debris volume in CY, divide by the container size, add 15 percent for the fluff and the underfill, and round up to the number of pulls. A 200 CY debris takeoff in 30 CY dumpsters is 7 pulls on paper and 8 pulls in practice. Price the 8.

Step by Step Material Takeoff

Work the takeoff in the same order the demo gets pulled, from the inside out.

• Step 1, pull the demo plan and the scope. Note what is coming out and what is staying. Identify selective demo (walls, ceilings, fixtures) versus full structural demo. Note the lead and asbestos survey because abatement is a separate line item.
• Step 2, measure the area to be demolished. For walls, multiply length times height to get SF of wall, then convert to CY of debris using the rule of thumb for the assembly. For ceilings, measure SF and convert. For fixtures, count the each. For concrete, measure SF times thickness and convert to CY with a 1.5 swell factor.
• Step 3, compute the dumpster count. Sum the debris CY. Divide by the container size (30 CY is common for interior demo). Add 15 percent for underfill and round up to the number of pulls. Multiply by the per load hauling charge.
• Step 4, compute the disposal fees. Convert the debris CY to tons (about 0.5 tons per CY for mixed interior demo, 1 ton per CY for concrete). Multiply by the per ton landfill rate. Add the tipping fee per load.
• Step 5, take off the recycling and salvage. Separate the clean wood, metal, and concrete from the mixed debris. Price the clean streams at the recycling rate, which is typically lower than the landfill rate. Deduct salvage value for fixtures that are sold or donated.
• Step 6, take off the protection and dust control. Measure the SF of floors and walls to be protected, the LF of poly containment, the number of zip wall doors, the number of HEPA scrubbers. Count the utility disconnections by the each.
• Step 7, apply waste factors and round up. Add the underfill and swell factor to the dumpster and disposal lines. Round up to the buy unit. Sum the priced quantities by spec division (02 41 00 demolition, 02 61 00 removal, 02 82 00 asbestos remediation where applicable).

Where Estimators Miss

The most common miss is computing the dumpster count from the plan area alone. A 5,000 SF selective demo is not 5,000 SF of debris. It is the walls and ceilings inside that area, which can be 2,000 to 3,000 SF of wall and 5,000 SF of ceiling, or 200 to 300 CY of debris. Measure the assemblies, not the floor.

The second miss is forgetting the swell on concrete. A 100 CY slab broken out is 150 CY in the container, and that is 5 pulls in a 30 CY dumpster, not 3. Apply the 1.5 swell factor before pricing.

The third miss is undercounting the protection. Floors that are not covered get scratched, and walls that are not covered get hit. Poly, masonite, and zip walls are line items that keep the job from turning into a repair job. List them.

The fourth miss is forgetting the utility disconnections. Every electrical, plumbing, and gas line that feeds the demo area has to be capped and tagged before the pull, and reconnected after. Count them by the each and price them, because they are a real cost and they get missed.

Worked Example

For a representative demolition scope, a 5,000 SF interior selective demo with 120 fixtures: the wall and ceiling debris runs about 250 CY, which is 8 pulls in a 30 CY dumpster with 15 percent underfill. Disposal at 0.5 tons per CY is 125 tons. Protection runs 5,000 SF of floor cover and 200 LF of poly containment. A typical direct cost breakdown for this scope is:

Numbers are illustrative and vary by region, project size, and material choice. Use them as a sanity check, not a bid.

Putting It Together

A demolition material takeoff is built from the assemblies coming out, converted to debris CY, padded with the swell and underfill factor, and rounded up to the number of pulls. Match the disposal to the tonnage, separate the clean streams for recycling, and list the protection and dust control. Price by spec division, total it, and the buy list is the bid. Get the volume and the pulls right and the containers leave on schedule.