Renovation estimate: how it is put together and how to check it

A contractor’s estimate is a table. Each line is one work item: what is done, on which surface, in which unit, in what quantity, at what rate and for what total. Lines are grouped by room or by type of work, such as demolition, walls, floors, electrical or plumbing, and each group has a subtotal.

Below the table the estimate should state what the price includes and excludes, how long it is valid and what it is based on: a site visit, measurements, drawings or only a description. An estimate made without a visit is a preliminary figure, not a basis for a contract.

The unit shows how a line was measured. Most finishing work is priced per square metre of the surface actually treated: floor area for screeds and floor coverings, wall area for plastering, tiling and painting, ceiling area for ceilings. Wall areas are normally measured without large openings such as doors and windows; if not, the estimate should say so.

Check the quantities against the plan or your own measurements. A difference of a few square metres per room adds up across a whole apartment, and a missing line usually turns into an extra later.

• Square metres (m²): floors, walls, ceilings, waterproofing, tiling, painting.
• Linear metres (m): skirting, trims, cornices, cable and pipe runs, sealed joints.
• Pieces (pcs): sockets, switches, light points, doors, sanitary fittings, radiators.
• Lump sum: items that cannot be measured in advance, such as site setup or waste removal; ask what each one covers.

An estimate may cover labour only, labour with basic materials such as adhesives, primers and fixings, or labour with all materials including finishes. Finishes such as tiles, flooring, sanitary ware and lighting are often chosen by the client and listed separately or excluded. The estimate should make clear which applies to each line.

Two groups of items are easy to overlook. Preparation covers protecting existing surfaces, demolition, removing old finishes, levelling, priming and taking away waste. Coordination covers site management, delivering and lifting materials, cleaning and the work of other trades such as electricians and plumbers. If these lines are missing, they have either been forgotten or are hidden in other rates.

An apartment renovation estimate is usually laid out by type of work. The sample below shows the structure only; the actual lines depend on the scope and on the condition of the property.

• Site setup and protection of surfaces: lump sum.
• Demolition of old finishes and partitions: m² or lump sum.
• Waste removal: lump sum or per container.
• Electrical rough-in: per point (pcs) or linear metres of cable.
• Plumbing and heating rough-in: per point (pcs) or linear metres of pipe.
• New partitions, wall levelling and plastering: m² of wall.
• Floor screed and levelling: m² of floor.
• Bathroom waterproofing: m².
• Wall and floor tiling: m².
• Filling and painting of walls and ceilings: m².
• Floor coverings and skirting: m² and linear metres.
• Doors, sanitary fittings and electrical devices: pcs.
• Final cleaning: lump sum.

Comparing the totals alone says little. Put the estimates side by side, line by line, and go through the same questions for each.

• Is the scope the same: the same rooms, surfaces and works?
• Are the quantities close, and measured in the same units?
• Which materials does each line include, and of what quality?
• Are protection, preparation, waste removal and cleaning included?
• Are site management and the coordination of other trades priced?
• What is excluded, and how will hidden defects be handled?
• How long is the estimate valid, and what are the payment terms?

The total changes for two main reasons: the scope and the condition of the property. The scope changes when the client adds or swaps items during the work, chooses different finishes or decides to replace wiring or pipes that were meant to stay. Each change should be agreed in writing, with its effect on cost and time, before it is carried out.

Condition is the hidden part. Uneven walls, a weak screed, old wiring, damp or rot often appear only after demolition. A good estimate names these risks and says how they will be handled, for example as separate items priced once the problem is visible. What Else prepares itemised estimates of this kind for apartment and interior renovation projects.