CAPEX estimation in real estate assets: methodology and common errors

A CAPEX estimate that blows up after acquisition is not bad luck. It is incorrect methodology.

It is one of the most repeated patterns in real estate transactions: the investment committee approves the purchase with a CAPEX estimate of €800,000. Twelve months after closing, the asset management team is handling real CAPEX of €1.6 million. Asset returns are compromised. The team looks for explanations. Nobody wants to own the error.

The problem is almost never that something unexpected appeared. The problem is that the estimation methodology was not designed to find it.

Why CAPEX estimates go wrong

There are three main causes, and all three are avoidable.

1. Visual inspection without documentary verification

A two or three hour site visit identifies what is visible. Hidden defects — damp in partitions, corrosion in steel structure under cladding, oversized or non-compliant installations — cannot be seen without access to drawings, maintenance reports, fault history and licence documentation. CAPEX estimated only on what can be seen is partial CAPEX. By definition.

2. Service life of building systems not calculated

HVAC, lifts, electrical installations and fire protection systems all have a technical service life. When that horizon crosses the expected holding period, CAPEX is virtually certain. An asset with eight-year-old HVAC and a ten-year holding period has an almost inevitable replacement cost within that horizon. Leaving it out does not make it disappear.

3. Outdated market prices

Construction costs in Spain have risen significantly in recent years. Estimates based on historical ratios or reference prices from two or three years ago systematically understate the real cost of intervention. A roof line item estimated at €45/m² that today costs €70/m² is not a minor error on assets of any scale.

A rigorous CAPEX methodology

A reliable CAPEX estimate has four phases.

Phase 1 — On-site technical inspection. Inspection of every building element and installation, with access to plant rooms, roof, basements and service areas, systematic photography and a record of defects.

Phase 2 — Documentary verification. Cross-checking the visual inspection against technical documentation: construction and refurbishment drawings, equipment data sheets, maintenance certificates, licences, energy performance certificates and statutory inspection reports. The documentation confirms, qualifies or contradicts what was observed on site.

Phase 3 — Service life and compliance analysis. For each technical system: estimated remaining service life, compliance status against current regulations and pending upgrade requirements. This analysis determines which CAPEX is mandatory, which is urgent and which is discretionary.

Phase 4 — Line-by-line budget with current prices. Each identified intervention becomes a budget line with current unit cost, estimated quantity, total amount and a recommended schedule. The output is a costed schedule, not a single global figure.

The five most common errors

1. Not separating mandatory from discretionary CAPEX. The committee needs to know what must be spent and what can be deferred. Mixing them distorts the decision.
2. Not including ESG CAPEX. Assets below minimum energy efficiency standards will require mandatory investment to retain value. That cost must be estimated at acquisition.
3. Forgetting indirect costs. Design and site supervision fees, licences, municipal taxes, temporary relocation. On significant works these can be 15-20% of the construction budget.
4. Not updating the estimate during negotiation. An estimate never revised in light of the seller's documentation is an incomplete estimate.
5. Estimating without knowing the specific asset. CAPEX ratios per m² are a starting point, not a result. Two assets of identical size can carry very different CAPEX depending on condition, last refurbishment and technical systems.

What makes an estimate useful for the investment committee

A useful CAPEX report is not a list of problems with associated costs. It is a document answering three concrete questions:

1. How much must be spent, and by when?
2. How much can be deferred, and until when?
3. How does this CAPEX affect asset returns over the investment horizon?

When CAPEX is well estimated, the committee can decide. When it is poorly estimated, it decides on the wrong basis.