Turns a strip out into a debris volume and a skip count, element by element.
Groundwork and site clearance. 5 questions answered below, each with the arithmetic behind it and the limits of what the tool decides. Open the Demolition and Debris Takeoff tool.
Demolition is priced by what leaves the site. The structure comes down easily enough on paper; the debris is what fills skips, needs lorries and costs money by the tonne or the cubic metre. This takeoff converts the elements you are removing into a loose volume, and the loose volume is the number the disposal is priced on. That conversion is the whole trick. A wall measured in cubic metres in place becomes a larger volume once it is broken, because broken masonry and concrete do not stack the way they stood. The bulking factor carries that change, and it is the difference between ordering four skips and needing seven. Where the factor is uncertain, the page says so rather than presenting a tidy number as fact.
A brick wall eighteen metres long, two point four high and two hundred and fifteen thick is about nine point three cubic metres in place. Broken, at a bulking factor of about one and a third, that becomes twelve and a half cubic metres loose, which is two skips of eight cubic yards with room to spare, or three if the skip is the smaller size. A concrete slab of forty square metres at a hundred and fifty millimetres adds six cubic metres, and seven and a half loose, so the job needs a third skip. Both figures came from the same rule, which is why mixing materials in one estimate still produces a usable total.
Measure each element in place, convert it to a solid volume, then apply a bulking factor to get the loose volume that goes in the skip. A wall of eighteen metres by two point four by two hundred and fifteen millimetres is nine point three cubic metres in place and about twelve and a half loose. The takeoff does that per element and per material, because the factor differs between brick, concrete and timber, and it rounds the result to skips at the capacity you hire.
Bulking is the change in volume when a material is broken up. A cubic metre of wall in place occupies more than a cubic metre of space once it is rubble, because the pieces do not fit together the way the wall did. Factors vary by material and by how finely it is broken, so the page applies one per material and shows it. Ignoring bulking is the most common way a demolition estimate comes out a skip short and the site stops waiting for a lorry.
From the loose volume and the capacity of the skip you hire. Eight cubic yards is a common size, smaller ones are available, and the takeoff rounds up to whole skips because half a skip is not a thing you can order. Loose volume divided by capacity gives the count, and where the total lands just over a whole number, the usual choice is the larger skip rather than a second visit, since a return trip costs more than the difference in capacity.
Yes, and they stay on separate lines. A job that removes a roof, a wall and a slab produces three different volumes with three different factors, and the total is their sum. Keeping them separate is what lets you see that the roof is most of the debris, or that the slab is what pushes the job from two skips to three. A single blended factor would give a total that is roughly right and cannot be checked against any single element.
No. Permits, notifications, asbestos surveys and disposal charges are outside the takeoff, and the last two matter more than they look. Asbestos cannot be identified from dimensions, and its presence changes both the method and the cost by an order of magnitude. Disposal charges vary by site, by material and by jurisdiction. The takeoff gives you the volume that those charges are applied to, which is the part it can honestly calculate.