A demolition estimate should state what comes down and what stays, the surveys and service isolations needed first, labour and plant, and each waste stream with its tonnage, container and disposal cost, then list exclusions such as asbestos and unknown ground. AI drafts the scope and waste lines from your site notes; you supply the quantities and rates.
Demolition prices go wrong in the parts nobody drew: the waste, the access and the hazards. A chatbot has never stood in the side passage, so it cannot know the barrow route is 25 m or that the roof sheets are grey and corrugated. It can keep a scope consistent, convert your measurements into tonnes when you show it the factors, and list what the estimate does not cover. The rest is your site notes and your judgement.
Write the scope as sentences before any numbers
The boundary decides the price: where demolition stops, what is retained and who makes good. Write that in sentences first, because every later line hangs from it. The worked job is a single-storey rear extension from the 1980s, drafted from notes like these (the figures throughout are illustrative):
Rear extension, 1980s, 4.5 × 3.2 m, single storey. Brick outer leaf, block inner leaf,
cavity. Flat roof: timber joists, boards, felt, some insulation. Concrete slab about
100 mm. One patio door (1.8 × 2.1 m), one window (1.2 × 1.0 m). Dry-lined inside.
Strip kitchen units and worktop. Radiator and pipework. Gas hob supply, power spur,
cold water, waste to gully. Opening into the house at one old window position.
Access: side passage 0.9 m wide; skip space on front drive; carry about 25 m.
Retain: house wall, damp-proof course, drain runs beyond 1 m from the extension.
Slab to come out; hardcore: designer to decide. Textured coating on kitchen ceiling,
age unknown. No survey seen yet.The prompt that turns notes into scope sentences has one rule that matters more than the rest: hazards and unknowns go in their own list and are never assumed away.
From the site notes, write the SCOPE section of a demolition estimate as numbered
sentences: what is demolished and to what extent (to slab level, or including the
slab), what is retained and protected, what is made good and what is not, how waste is
segregated, and where our work stops. No prices. If the notes mention a hazard or an
unknown (textured coatings, sheet materials, tanks, unseen services, ground below
the slab), list it under HAZARDS AND UNKNOWNS and do not assume it is safe or absent.A usable result looks like this:
1. Demolish the single-storey rear extension, about 4.5 m by 3.2 m: flat timber roof, cavity masonry walls, window and door, internal linings, kitchen fittings and the concrete slab, down to formation level. 2. Retain and protect the house rear wall, its damp-proof course and the drain runs beyond 1 m from the extension; fit a temporary weatherproof closure to the opening in the house wall. 3. Gas, electricity and water to the extension are isolated and capped by others before work starts; we cap two drain runs at the extension edge. 4. Waste is segregated into rubble, timber and mixed, plasterboard and scrap metal. 5. Our work stops at slab removal; hardcore, foundations and anything below formation level are excluded unless a provisional sum is stated. HAZARDS AND UNKNOWNS: textured coating on the kitchen ceiling (composition unknown); no asbestos survey seen; no service isolation confirmations seen; ground below the slab unknown.
Check sentence 2 against what you promised the client. "Retain and protect" costs money, and "make good" costs more, so say which one you mean. Here, making good is limited to the temporary closure. Permanent plastering and decorating belong to whoever builds next. Sentence 1 puts the slab in the demolition, as the notes say, and sentence 5 leaves the hardcore to a provisional sum because the designer has not decided.
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Buy nowBefore the price: surveys, services, notices and neighbours
Several things must happen before anyone swings a hammer, and the estimate should show who is responsible for each. The assistant's job is to keep them visible; ask for a PRE-START CONDITIONS list drawn from your notes, each item marked included, excluded or by others.
| Item | Why it comes first | How the estimate treats it |
|---|---|---|
| Asbestos survey of the parts coming down | A routine management survey for an occupied building does not cover work that opens up the structure. Before demolition, an intrusive survey (called a refurbishment and demolition survey in some places) is commonly required | A condition of the price: the survey is in hand before the start date. Any asbestos found is excluded and priced separately by a specialist |
| Structural check of what is attached | Walls tied to the house or a lintel over the old window opening may carry load | Any propping or temporary support designed by an engineer is excluded or a provisional line |
| Isolation of gas, electricity, water, communications | Live services inside a wall injure people | Isolated by the client's appointed suppliers or registered contractors; written confirmation held before start; excluded from the price |
| Drains | Hidden runs get broken in the first hour | Provisional sum to locate and cap |
| Notices and permits | Some places need notice before demolition, or a permit for a skip on the public road | Our time to apply is included; fees are the client's; this job's skip sits on the drive |
| Neighbours and shared structure | Noise, hours and any wall you share | Working hours stated; written agreements with neighbours are the client's job |
| Wildlife | Some places protect bats and nesting birds, and roofs and old buildings can hold them | Client confirms any ecological check; work stops if protected species are found |
None of these is a drafting task, and the AI should not decide any of them. A rule I would keep in the standing prompt: no demolition starts until the file holds the survey and written confirmation that services are isolated, and every draft estimate says so in its conditions. For the paperwork that follows from this, a job hazard analysis template drafted with AI is a useful companion, and what a person must check in an AI-drafted risk assessment covers the sign-off.
From site measurements to tonnes, with the factors on show
Disposal is charged by weight, so measurements have to become tonnes. This is arithmetic, which the assistant does well when it shows its working and badly when it does not. Give it your measurements and your factors, and demand a table. Reference tables list brickwork at roughly 1,600 to 1,800 kg per cubic metre, dense concrete at 2,000 to 2,400 and plasterboard at about 800; use your waste contractor's own factors where they publish them. This job uses 1,800 for brick, 1,600 for block, 2,400 for the slab and 800 for plasterboard.
The wall area first. Three walls come down: 4.5 m plus 2 × 3.2 m is 10.9 m, times 2.5 m high is 27.25 m². Take off the patio door (3.78 m²) and the window (1.2 m²) and the net wall area is 22.27 m², say 22.3 m². The house wall stays, so it is not counted.
| Element | Measure | Factor | Tonnes |
|---|---|---|---|
| Brick outer leaf | 22.3 m² × 0.10 m = 2.23 m³ | 1,800 kg/m³ | 4.0 |
| Block inner leaf | 22.3 m² × 0.10 m = 2.23 m³ | 1,600 kg/m³ | 3.6 |
| Concrete slab | 14.4 m² × 0.10 m = 1.44 m³ | 2,400 kg/m³ | 3.5 |
| Plasterboard linings | 22.3 m² × 12.5 mm | 800 kg/m³ | 0.2 |
| Roof timber and decking | Allowance | - | 0.3 |
| Roof covering and insulation | Allowance | - | 0.2 |
| Kitchen units and worktop | Allowance | - | 0.4 |
| Window, door and glass | Allowance | - | 0.2 |
| Metals (radiator, pipework) | Allowance | - | 0.1 |
| Total | 12.5 |
The classic draft error here is counting the wall you are keeping. A draft that adds the house wall (4.5 m × 2.5 m is 11.25 m² more) inflates the masonry by about 3.8 tonnes. That tips the rubble into a third skip and adds $266.20 (3.8 t × $24 a tonne is $91.20, plus a $175 skip) to a price for work you are not doing. The fix lives in the prompt: list what is retained, and tell the assistant to exclude retained elements from every quantity.
Spot-check the allowances as well. If your records from similar jobs say a kitchen strip-out weighs 0.6 tonnes, not 0.4, change the number and tell the assistant to use it every time. For general help turning supplier prices into reusable rates, building a rate sheet from supplier quotes covers the other half of this table.
Waste by stream: rubble, timber and plasterboard on separate lines
Clean rubble is the cheapest waste to get rid of, and mixed waste typically costs more per tonne, so putting everything in one mixed skip is the expensive way to demolish a building. Each stream gets its own container and its own pair of lines: one for hiring and hauling the container, one for disposal by weight. The rates below are placeholders for your waste firm's price list.
| Stream | Contents | Tonnes | Container | Hire and haul | Disposal |
|---|---|---|---|---|---|
| Rubble | Brick, block, concrete | 11.1 | 2 skips | 2 × $175 = $350.00 | 11.1 t × $24 = $266.40 |
| Timber and mixed | Roof timber, kitchen units, roof covering, insulation, frames, glass | 1.1 | 1 skip | $190.00 | 1.1 t × $118 = $129.80 |
| Plasterboard | Wall linings | 0.2 | 1 bag | - | $95.00 flat |
| Scrap metal | Radiator, pipework | 0.1 | Set aside | - | Collected at no charge |
The waste lines total $1,031.20. Now test the boundary. If a rubble skip takes about 6 tonnes of heavy material (an assumption: ask your supplier for its limit), two skips hold 12 tonnes. The estimate says 11.1, which is 0.9 under. A 10% error makes it 12.2, and that needs a third skip. So the estimate carries a conditional line: "Rubble disposal is reconciled to weighbridge tickets at $24 a tonne; if the total exceeds 12 tonnes, an additional rubble skip is charged at $175." The client sees the risk in advance and you are not eating it.
Keep the paperwork for every load: the weighbridge ticket or transfer note, whichever form the rules where you work require. The estimate should carry a no-charge line that says the paperwork is retained and available, because clients and accountants ask later where the rubble went. Check the other end of the chain before the first load, too: have the assistant add a pre-start line confirming that the skip firm or haulier is registered or licensed to carry waste where you work, and that the receiving site is permitted to take each stream, plasterboard included. If skips sit on the road rather than a drive, check permit rules and lead times; a skip hire software checklist covering quotes and permits sets out what a supplier should handle.
Access and plant: how a 0.9 m side passage moves the price
Access decides whether a machine can do the work, and that is the biggest swing in the estimate. The side passage here is 0.9 m wide and the skip sits 25 m away on the drive, so the choice is a narrow-access machine, if the hire firm can supply one that fits the passage, or hand demolition with barrows. Ask the assistant to produce both versions side by side from the same quantities:
| Hand demolition | Narrow-access machine | |
|---|---|---|
| Operative-days | 12 | 6 |
| Labour at $210 a day | $2,520 | $1,260 |
| Plant | Electric breaker, 3 days × $65 = $195 | Machine, 3 days × $185 = $555, plus $120 delivery and collection |
| Labour and plant | $2,715 | $1,935 |
The machine route saves $780 before markup, or $936 with the 20% added below. The estimate in the next section uses the machine, and states the assumption: a machine narrower than the passage, confirmed by the hire firm in writing. If the passage cannot take it, the price rises by $936. That sentence belongs in the conditions, not buried in a note.
The assistant earns its keep on the questions you forgot to ask. Tell it to read your notes and list access questions: gate and passage widths, carry distance, ground-bearing limits for a machine, parking and delivery times, neighbours' hours, anything overhead. It will often notice that "skip space on front drive" says nothing about whether the drive can take a loaded skip lorry, which is a call to make before the quote, not after.
The estimate in one table: extension demolition, line by line
With scope, quantities, containers and method settled, the master prompt assembles the lines. Give the assistant your rate card and ask for quantity and unit only, with the arithmetic left to you.
Using the scope, the tonnes table, the container plan and my rate card, list the
estimate lines: code, description, quantity and unit. Do not multiply or total.
Add a CONDITIONS list (survey, service isolation, access assumption), an EXCLUSIONS
list, and any PROVISIONAL lines. Anything not in my notes or rate card goes under
QUESTIONS, not into a line.| Line | Description | Qty | Unit | Rate | Total |
|---|---|---|---|---|---|
| A1 | Site set-up, dust sheets and protection to the retained house | 1 | sum | $240 | $240.00 |
| A2 | Temporary weatherproof closure to the opening in the house wall | 1 | sum | $260 | $260.00 |
| B1 | Operatives, strip-out and demolition | 6 | day | $210 | $1,260.00 |
| B2 | Narrow-access machine with breaker | 3 | day | $185 | $555.00 |
| B3 | Machine delivery and collection | 1 | sum | $120 | $120.00 |
| C1 | Rubble skips, hire and haul | 2 | skip | $175 | $350.00 |
| C2 | Rubble disposal by weight | 11.1 | tonne | $24 | $266.40 |
| C3 | Mixed skip, hire and haul | 1 | skip | $190 | $190.00 |
| C4 | Mixed disposal by weight | 1.1 | tonne | $118 | $129.80 |
| C5 | Plasterboard bag, collected and disposed | 1 | bag | $95 | $95.00 |
| D1 | Locate and cap two drain runs (provisional sum) | 1 | sum | $360 | $360.00 |
| E1 | Hardcore removal and disposal if required (provisional sum) | 1 | sum | $400 | $400.00 |
Total it yourself. Preliminaries come to $500, labour and plant to $1,935, waste to $1,031.20, drains to $360 and the hardcore provisional sum to $400, a subtotal of $4,226.20. Overheads and profit at a placeholder 20% add $845.24, so the estimate is $5,071.44. If the machine cannot get through the passage, the hand-demolition version is $6,007.44.
Exclusions and provisional lines that protect the price
An exclusion without a pricing route is an argument waiting to happen. Each line below says what is left out and what happens if it turns up. Ask the assistant to rewrite your usual exclusions in this shape, using the site notes, and to delete any that do not apply.
| Excluded | If it turns up |
|---|---|
| Asbestos and other hazardous materials | Work stops. Removal by a suitably qualified specialist is priced separately after the survey; our programme moves with theirs |
| Isolation of gas, electricity, water and communications | Done by the client's appointed suppliers. We start only with written confirmation |
| Anything below formation level (foundations, tanks, old drains, obstructions) | Day rates on written instruction: $210 per operative-day, $185 per machine-day |
| Hardcore removal | Covered by the $400 provisional sum; actual quantity and cost replace it |
| Making good beyond the temporary closure | Priced on request; plastering and decorating are not included |
| Temporary works designed by an engineer | Priced after the engineer's design |
| Permit, notice and skip-placement fees | The client's cost; our time to apply is included |
| Rubble above 12 tonnes | Third skip at $175; all rubble disposal reconciled to weighbridge tickets at $24 a tonne |
Notice the lines that carry a dollar figure: the day rates, the hardcore sum and the third skip. They are not padding. A provisional sum is the client's early warning of a cost you cannot yet know, and the estimate should say that actual cost replaces it. Variations that arrive mid-job need the same clarity; pricing variations and change orders with AI shows the paperwork.
The roof sheet the draft called scrap metal
A different job, a detached garage, shows how this goes wrong in practice. The notes say "12 corrugated roof sheets, grey". The assistant puts them under scrap metal and gives them a tonnage, which means a skip, a price and a crew told to carry them. A grey corrugated roof on an older building may be asbestos cement. Nothing in the notes says it is safe, and the estimator is not the person who decides.
Rule for every estimate: any sheet, board, coating, tile or lagging whose composition
is not recorded is a SUSPECTED hazardous material until a survey says otherwise.
Never give it a tonnage, a container or a disposal line. List it under HAZARDS AND
UNKNOWNS, add it to EXCLUSIONS with a stop-work clause, and ask me for the survey
result.The same rule would catch the textured ceiling coating in the extension notes, and any floor tiles or pipe lagging the notes mention. The point is structural: the assistant should never be able to convert an unknown into a priced line. Before an estimate leaves the office, run one more prompt: "List every line that relies on an assumption not stated in my notes." A short list means the draft is honest; a long one means the notes are thin and the site visit needs repeating.
After the job: weighbridge tickets against the estimate
The best conversion factors are your own. After each job, compare the estimate with the tickets and keep the differences in one table. Here, illustratively, the rubble came back at 12.4 tonnes against 11.1 estimated, 11.7% more. The slab turned out to be 130 mm thick in places, not 100: at 130 mm it would weigh 4.5 tonnes instead of 3.5, which explains about a tonne of the gap. The conditional third-skip line recovered $206.20 ($175 for the skip plus 1.3 t × $24 of extra disposal), so the job lost nothing, but the next estimate should say "probe the slab thickness" in the site visit checklist.
Ask the assistant to maintain that table: "Add this job to the history. For each stream, show estimated tonnes, actual tonnes, the percentage difference and the likely cause from my note." After five jobs you have factors better than any published table, and you can tell the assistant to check each new estimate against them.
Questions from demolition and strip-out firms
Can AI work out tonnes from my measurements?
Yes, as arithmetic, provided you give it the measurements and the conversion factors and ask for the working as a table. Left alone it chooses its own factors and does not say so. Check the total in a spreadsheet, and compare each stream with the weighbridge tickets from your last three similar jobs before you trust a figure.
Should the estimate include asbestos removal?
Not unless a survey has found some and a suitably qualified specialist has priced it. Write asbestos and other hazardous materials as an exclusion with a stop-work clause, and make the survey a condition of the price. Rules on who may remove what differ by place, so check yours and let the client's specialist quote the removal.
How do I price ground I cannot see?
Do not guess it into the fixed price. Exclude everything below formation level, such as old foundations, tanks and drains, and offer day rates for labour and plant on written instruction. If the client wants a number, give a provisional sum for the likeliest item, state what it covers, and say that actual cost replaces it.
Further reads
- How to Write a Method Statement for a Small Build, With AI Help — Turn the scope sentences into a method statement for the crew.
- How to Price Excavation Work: Hourly, Per-Load or Fixed, Checked With AI — Hourly, per-load or fixed pricing for the dig that follows demolition.
- Concrete Estimate Template: Volume, Pump and Finishing Lines With AI — Volume and pump lines for the slab that replaces what you remove.
- Drywall Estimate Template: Scope Lines and Exclusions Written With AI — Scope and exclusion wording for the next trade in the building.
- Loft Conversion Quote Template: Stages and Provisional Sums With AI — More worked examples of provisional sums in a stage-based quote.
- Groundworks Quote Template: Dig, Drain and Base Lines Written With AI — Dig, drain and base lines for the work that follows demolition.
- Bathroom Remodel Estimate Template: Catch Missing Lines With AI — The hidden lines that slip out of bathroom estimates, a checklist prompt that audits your last three, and a reusable template with allowances for unknowns.
- Dumpster Rental Software: Bookings, Swaps and Routes With AI — What a small yard needs from dumpster rental software, how AI can take bookings and plan swap routes, and a trial script to test any system.
- Landscaping Estimate Template: Itemise Labour, Plants and Waste With AI — A worked front-garden estimate with labour, plant, materials and waste lines, a margin check, and four AI prompts that do the typing, not the pricing.
- Renovation Quote Template: Room-by-Room Scope Written With AI — A room-by-room renovation quote with stage grids, allowances and exclusions, plus prompts that draft clear wording from your survey notes.
- Siding Estimate Template: Squares, Trim and Waste Lines Written With AI — A siding estimate laid out line by line, with the squares, trim and waste sums worked from wall measurements and a ChatGPT pass for missing items.
- Tree Service Estimate Template: Itemise Jobs With AI — A filled-in tree service estimate: removal, crane, chipping, stump grinding and haul-away as separate lines, with exclusions, conditions and a follow-up text.
- AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.
Sources: published material density tables for brickwork, concrete and plasterboard; trade guidance on asbestos survey types; ChatGPT and Claude help pages. All rates, fees and container limits in the examples are placeholders to replace with your own supplier prices.