Site survey and quantity take-off: start from the real existing building to secure your renovation cost estimate
Prepare the visit: drawings, photos, access, constraints and risk points
Before you go, gather drawings, sections, utility markings and dated photos. Lock down access, simultaneous operations, protected areas, working hours, and measurement logistics. Note the risk points. Structure, asbestos, lead, moisture, duct runs, and the height and load-bearing capacity for the scaffold.
Carry out the survey and take-off: surfaces, linear dimensions, volumes, thicknesses, heights
On site, follow a logical route, envelope first, then rooms. Cross-check measurements with control dimensions and tagged photos. Produce a take-off that can be used for cost estimating, in work-package units. To go further, rely on a structured building quantity take-off method.
| Measure | Unit | Record to keep |
|---|---|---|
| Wall area | m² | dimensioned sketch |
| Network run | m | reference photo |
| Technical volume | m³ | calculation |
| Thickness, height | mm, m | measurement photo |
Record your assumptions about the existing condition: what you know, what you assume, what you must open up
In your estimating documents, separate confirmed existing conditions, assumed existing conditions, and anything that requires opening up or trial holes. Price uncertainty as a written contingency (removal, repairs, disposal), rather than absorbing it as extra work.
Break the project down into work items: the basis of line-by-line renovation cost estimating
Build your work-item list: stripping out, substrates, supply, installation, finishes
For reliable renovation cost estimating, think in terms of a bill of quantities / priced schedule. One work item = one measurable action and one unit. Break it down systematically.
- Removal and disposal, including protection.
- Substrate preparation, repairs, levelling, treatment of critical points.
- Materials, accessories, fixings, consumables.
- Installation, adjustments, testing, commissioning where applicable.
- Finishes, cleaning, handover minutes and as-built file if planned.
Define the scope boundaries: interfaces between trades and responsibilities
Set the interfaces out clearly in the quote and the technical specification. Who removes and reinstalls the equipment, who makes good, who reinstates airtightness, who handles penetrations. A written boundary avoids unpaid “small” items.
Organise your items according to the site sequence: avoid omissions and duplicates
Arrange the work items in the actual order of the job, from set-up to demobilisation. You check dependencies (scaffolding, access, shutdowns, protection) and spot duplicates between trades. At the end, a “mobilisation, demobilisation, cleaning” line closes the list.
Price each work item on a net cost basis: quantities, labour and plant
Material quantities: units, waste, pack sizes, delivery and storage
In renovation cost estimating, start from the take-off and convert each component to its purchasing unit. Add a “waste and offcuts” line and an “accessories” line rather than spreading the cost thinly. Check pack sizes, minimum order, unloading method, storage area and risk of damage. Record this choice on the quote and keep delivery notes and technical data sheets.
| Item | Unit | Point to lock down |
|---|---|---|
| Main product | m² | Pack size, waste |
| Accessories | u | Compatibility, batches |
| Removal and disposal | m³ | bulk bags, skip, waste stream |
Labour time: productivity, difficulty, rework, access constraints and simultaneous operations
Calculate time per work unit from your own historical data. Then adjust for access, height, work on the existing fabric, protection, noise and simultaneous operations. Formalise your assumptions in the survey notes and timesheet.
| Task | Work unit | Time allowed |
|---|---|---|
| Removal | m² | h/unit |
| Installation and sealing | m² | h/unit |
| Cleaning and demobilisation | lump sum | h |
Plant and consumables: tools, hire, small hardware and protection
Separate amortised tools, hire items (scaffolding, core drill, lifting equipment), and consumables. Always include screws and fixings, sealants, tapes, PPE, floor protection and cleaning. Rely on industry benchmarks and ADEME guidance to frame the items according to the task. To frame the overall document, also see how to structure lots, items, taxes and exclusions in a construction quote.
- Hire and transport: round trip, handling, fuel.
- Consumables: hardware, sealing, films, bags, abrasives.
Add site overheads, general overheads and a selling coefficient: turn net cost into a sale price
Site overheads often forgotten: mobilisation and demobilisation, travel, scaffolding, protection, cleaning
In your renovation cost estimate, keep these costs out of the work items’ net cost. Price them as dedicated lines, with a clear basis (day, trip, surface, access). Otherwise, they disappear into ratios and come back as extra work.
- Mobilisation and demobilisation, parking, skips and waste removal.
- Scaffolding, lifting, protection, barriers.
- End-of-day cleaning, completion cleaning.
General overheads in 2026: what they cover and how to allocate them correctly
General overheads cover structure, insurance, vehicles, workshop, administration, software, certification, training, shared tools. Allocate them with one simple rule, same basis for all your quotes.
| Allocation basis | When to use it |
|---|---|
| Productive labour hours | Jobs with a high installation share |
| Net cost amount | Packages balanced between materials and labour |
Apply your selling coefficient: a simple method aligned with your margin targets
First establish the cost price: net cost, site overheads, share of general overheads. Then apply a single selling coefficient by trade type, and check the margin item by item. Adjust if a work item is risky or subcontracted. To cover the overall form of the document as well, rely on the best practice for a compliant quote for energy renovation work.
Check the margin and manage uncertainty in the existing building: avoid the “price per m²” trap
Check the margin by item: identify the items that drag profitability down
In renovation cost estimating, lock down the margin item by item, not just overall. Compare net cost (materials, labour, hire, subcontracting) with sale price. The usual underperformers are stripping out, protection, disposal, finishing, and anything done “while you’re there”.
| Item | Net cost (€) | Sale price (€) | Gross margin (%) |
|---|---|---|---|
| Removal and disposal | |||
| Protection, cleaning | |||
| Main work item |
Price uncertainty: written contingencies in the quote, options, provisional items and controlled unknowns
On existing buildings, treat the unknown as a line item. A written contingency describes the inaccessible area, the assumption used, and the trigger for repricing. Add priced options and provisional items (repairs, services, moisture), with units, prices and an approval method before execution.
Anticipate extra work: what must be allowed for from the outset of the renovation cost estimate (stripping out/disposal, repairs, protection)
Do not let “extras” get created on site. Provide dedicated lines for stripping out and sorting, disposal, mobilisation and demobilisation, scaffolding, drilling and making good, protection, cleaning, local repairs, testing and adjustments. You contain the risk instead of absorbing it.
