1. The basic principle: measure what is done, not what remains
The fundamental rule of refurbishment measurement is to measure what is actually carried out, including the enabling work, the strip-out and the disposal, and not merely the visible end result. In new build, the tiling in a bathroom is measured as the area laid. In refurbishment the same item comprises removing the old tiling, levelling the substrate, laying the new tiling and taking away what was removed. Each of those four operations has its own unit, its own rate and its own line in the bill.
That distinction has a direct effect on the structure of the bill. A well-built refurbishment bill always has more lines than a new build bill for the same area, because it separates the deconstruction and reconstruction phases that coexist within every package.
2. Units by type of work
| Type of work | Unit in new build | Unit in refurbishment | Key difference | Example |
|---|---|---|---|---|
| Demolishing partitions | m² or linear metre by thickness | A refurbishment-specific unit with no new build equivalent | Plasterboard at 100 mm: 12 €/m²; brick at 200 mm: 22 €/m² | |
| Removing tiling | m² removed | The area removed is not the area relaid, given cuts and waste | 85 m² removed for 80 m² relaid; measure the area removed | |
| Removing joinery | Number | Priced per unit by type and height | A 2,04 m door at 80 €; a 2,40 m door at 120 €; a window at 100–200 € | |
| Removing a roof structure | m² of roof or by volume | Valued on the volume taken down plus disposal | Traditional structure over 120 m²: 15 €/m² to remove, 8 €/m² to dispose | |
| Renewing façade render | m² in new build | m² following the existing profile | An irregular substrate increases material consumption | 15 to 30 % more material than render on a flat new substrate |
| Internal insulation lining | m² of habitable area | m² of insulation installed, gross area | The gross area is not the habitable area after lining | The habitable area lost is the thickness times the perimeter insulated |
| Repairing masonry | m³ or linear metre by nature | Openings, infills, local repairs | Infilling an opening: 250–800 € by size and type of masonry | |
| Clearing voids and sub-floors | m³ or lump sum | Work that cannot be quantified precisely before access | Always a lump sum, with an option for additional work |
ℹ The trap of area removed against area relaid In refurbishment the area removed and the area relaid are not always the same. Removing tiling from a bathroom means removing the whole tiled area, including under the partitions that are staying, behind the fittings, and in the awkward zones with complex cuts. The area relaid is the net area of new tiling after cutting. The rule: measure the area removed for the removal item, and the net area installed for the laying item. The two carry different rates in the bill.
3. Where the technical codes meet existing fabric
The French technical codes define good practice for installing the work. In refurbishment their application meets the reality of an existing substrate that was not designed to receive today's materials and does not offer the dimensional tolerances of a new one. The economist has to reflect those specifics in the bill as preparation items.
| Field | Applicable code | The refurbishment specific | Effect on the measurement |
|---|---|---|---|
| Masonry | DTU 20.1 | Old walls fall outside the dimensional tolerance; the code allows greater deviation in refurbishment | Measure levelling and flatness repairs separately from the masonry item |
| Façade render | DTU 26.1 | The old substrate has to be tested, with a preparation premium where it is friable | A substrate preparation item at 5–15 €/m² before the render |
| Tiling | DTU 52.1 | Greater substrate deflection is allowed in refurbishment, but a levelling screed is often needed | Measure removal, levelling and laying separately |
| Timber flooring | DTU 51.1 | Flatness and moisture content of the old substrate have to be checked, with a drying period if a new screed is laid | Allow 21 days where a cement screed is laid over a damp substrate |
| Internal insulation | DTU 25.41 and 45.10 | The insulation thickness has to fit the space available, a dimensional constraint absent in new build | Measure the gross area and state the habitable area lost |
| Roof covering | DTU 40 series | Existing covering elements that are retained have to be inspected and scheduled before the works | Measure separately: inspecting and repairing the existing, partial replacement, full replacement |
| Plumbing | DTU 60.1 | Existing pipework that is retained has to be pressure tested; its size may no longer suit | Carry provisions for repairing degraded existing services |
4. Careful removal: not the same as demolition
Careful removal means taking elements out while preserving them, for reuse or for reinstallation. It differs from demolition, which is destruction without preservation, in its more demanding conditions and its higher cost.
Removing joinery for reuse: two to three times the cost of simple removal, requiring trained operatives and secure storage. Priced per unit with a premium for care.
Removing quality tiling such as granite or marble: careful removal costs 3 to 5 €/m² more than standard removal, and allows the material to be recovered for reuse elsewhere or for resale.
Removing recoverable equipment: radiators, sanitary fittings, water heaters. Careful removal for reuse has to be specified, with the storage conditions stated.
Confusing careful removal with demolition in the bill is a frequent source of dispute at final account: the contractor charges careful removal above the scheduled rate if the distinction was not drawn at tender.
5. The eight items most often missing
| Item missed | How often | Budget impact | How to carry it in the bill |
|---|---|---|---|
| Substrate preparation: levelling, keying, hacking off | Very often | 3–12 €/m² by nature | A dedicated line per package, never inside the laying rate |
| Protection of retained work: sheeting, board, covers | Often | 1–3 €/m² | A lump sum or a rate per m² of surface protected |
| Isolating and reconnecting the services | Often | 500–3 000 € per service | A dedicated line per service: water, gas, power, mechanical |
| Final clean | Very often | 3–8 €/m² | A lump sum or a rate, in every package concerned |
| Skips and waste disposal | Very often | 80–200 € a load, plus segregation | A dedicated line in every package producing significant waste |
| Difficult access: stairs, restricted lift, narrow courtyard | Project-dependent | 5–20 % of the package | A percentage on the package total, or a lump sum after a visit |
| Temporary supplies: water and power for the site | Often | 1 500–5 000 € by duration | A site establishment line, usually in a preliminaries package |
| Making good after the other trades | Very often | 3–8 % per package | An interface making-good line in the sensitive packages, partitions and floors |
The items marked very often are the ones that reappear systematically as variations on badly prepared refurbishment sites. Carrying them in the bill from the outset avoids the requests for additional work that sour the relationship with the contractor and destabilise the budget.
6. Measuring without drawings
Where drawings do not exist or are incomplete, the economist has to estimate the areas from a visit with measuring tools. The recommended method is a room-by-room laser survey: a laser measure costing under 100 € gives lengths and heights with enough precision for an estimate from rates.
Floor areas: measure length by width inside the walls for each room, and add them to obtain the approximate habitable area.
Façade areas: measure the external perimeter by the façade height, and deduct the openings, allowing 1,5 m² for a standard window and 2,0 m² for a French door.
Roof area: measure the footprint and apply a pitch factor, 1,15 at 30° and 1,25 at 45°, or measure directly where access is safe.
Partition runs: measure in linear metres at finished height, noting the material, plaster, brick, concrete, so the right rate can be applied.
ℹ What precision a visit without drawings can give A survey carried out with a laser measure by an experienced economist gives areas reliable to within 5 to 8 %. That precision is sufficient for an estimate from rates, which is itself accurate only to within 15 to 25 %, but insufficient for a line-by-line bill. For a precise bill, a full measured survey by a surveyor or architect, accurate to within 1 to 2 %, is indispensable. Its cost, 1 000 to 5 000 € depending on the size, is amply repaid by the variations it prevents.
In summary
Refurbishment measurement covers what is executed, removal, preparation, installation, disposal, not merely the end result. The units change with the type of work: area removed is not area laid, joinery is counted by number, lintels by linear metre, clearing by volume. The technical codes apply differently to an existing substrate, and substrate preparation is a compulsory item. The eight items most often missing are substrate preparation, protection of retained work, isolating the services, the final clean, waste disposal, difficult access, temporary supplies and interface making-good. A laser survey gives 5 to 8 % precision, enough for rates but not for a line-by-line bill.
The nature of the figures quoted
The percentages and amounts quoted on this page are orders of magnitude for framing, not measurements. They illustrate mechanisms and proportions, and they substitute neither for a tender exercise nor for an estimate prepared on drawings.
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Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.