Which documents are required for a TDD?

The data room should contain floor plans and building specifications, energy performance certificates, maintenance and inspection records for the building services, the modernisation history, extracts of the tenancy structure and consumption data for the last three years. Missing documents are recorded in the report as limitations — what was not provided remains a risk.

Technical Due Diligence – Scope & Process

Definition

What Is a Technical Due Diligence?

A Technical Due Diligence (TDD) is the systematic technical risk assessment of a property before acquisition, refinancing or strategic repositioning. It evaluates building fabric, building services, hazardous materials risks, fire protection and energy performance, and translates the findings into a quantified investment plan (CAPEX) with ranges. The governing reference for scope and report structure is the RICS professional standard Technical due diligence of commercial, industrial and residential property in continental Europe; AHO Booklet 21 (due diligence) serves as the complementary German reference. Work follows the MP four-phase TDD model (two process variants).

In institutional transactions, the TDD runs in parallel with the legal, financial and tax due diligence. It answers four questions: What is the technical condition? What investment obligation follows — short, medium and long term? Which risks cannot be quantified? And what does this mean for the purchase price or the long-term budget? Cost structures follow the cost groups of DIN 276, the German standard for construction costs; the maintenance logic follows DIN 31051, the German maintenance standard (inspection, servicing, repair, improvement).

Who It Is For

TDD for Mid-Sized Portfolio Holders — Not Only for Corporate Deals

The large inspection organisations serve portfolio transactions of institutional investors. Housing companies with 200 to 5,000 residential units need the same methodical quality — scaled to single assets and small portfolios.

Acquisition & Densification

Technical plausibility check of single assets and small portfolios before the notary appointment: deal-breakers, maintenance backlog, immediate measures — as a basis for negotiation.

Refinancing & Strategy

CAPEX transparency for banks, supervisory boards or shareholders: remaining useful life per building element group and a 10-year investment path, including the requirements of the GEG, the German Buildings Energy Act.

Disposal Preparation

Vendor due diligence: knowing the technical findings before the buyer does means negotiating from the stronger position and avoiding surprises in the data room.

Scope of Services

TDD Service Phases: The MP Four-Phase Model

The scope of services follows the MP four-phase TDD model: four phases from commissioning to handover, with defined deliverables per phase — in two process variants, depending on when the data room becomes available.

Phase	Services	Deliverable
Phase 1 — Data Room Analysis	Documented target/actual review of the property records; review of building files, permits, energy performance certificates, maintenance contracts, damage and defect history; identification of red flags and inspection priorities; for portfolios: screening and sampling.	Document inventory, preliminary red flag report, list of missing documents
Phase 2 — Site Inspection / Condition Survey	Structural inspection (load-bearing structure, envelope, roof, facade, windows, interior fit-out) along the cost groups of DIN 276; building physics indication (thermal, moisture and sound insulation as samples); building services sample (heating, ventilation, plumbing, electrical, lifts); optional drone survey and thermography via external partners. 4 to 8 hours per asset, more than 100 systematically assigned photos.	Inspection protocol, measurements, defect catalogue with photo references
Phase 3 — Analysis & Assessment	Condition rating per building element group with remaining useful life and renovation urgency; 10-year CAPEX plan based on BKI cost benchmarks (the German construction cost index) with the NRW regional factor; risk matrix (probability × impact) with traffic-light rating; TDD report with management summary.	TDD report (Red Flag: 15–25 pages, full scope: 40–80 pages), CAPEX tables as Excel annex
Phase 4 — Documentation / Report	Closing workshop (90 minutes, remote or on site); explanation of top risks, CAPEX scenarios and recommendations to management or board; follow-up on queries.	Management presentation, finalised report with release date

Two process variants: In the standard process (variant A) the data room is available before the inspection — the phases run in order 1 to 4. In the alternative process (variant B) the site inspection comes first; on request, a Red Flag report provides an optional early indication of the key risks and cost drivers before the data room opens. The Red Flag TDD product corresponds to variant B up to and including the Red Flag report; the full-scope TDD covers the complete run.

Not included and commissioned separately where required: hazardous materials sampling with laboratory analysis (asbestos, mineral fibres, PAH, PCB), structural engineering surveys, detailed building physics (sound measurements, blower door test), legal, tax and ESG taxonomy review, market valuation pursuant to Section 194 of the German Federal Building Code (BauGB).

Report

What a Standard-Compliant TDD Report Contains

The report structure follows a fixed framework that institutional recipients — banks, boards, asset managers — expect and can process directly.

Core Chapters

Scope and methodology (including documented limitations) · Executive summary with CAPEX benchmark (euros per m² or total) · Asset description · Structural works (cost group 300 per DIN 276) · Building services (cost group 400) · External works (cost group 500).

Risk and Forward-Looking Chapters

Hazardous materials and environment (asbestos, mineral fibres, PAH, PCB, contamination risks) · Energy performance with GEG compliance and decarbonisation pathway · Fire protection and grandfathering status · CAPEX planning by time cluster with ranges · Risk matrix · Annexes with photo documentation.

A TDD is a decision-making report, not forensic evidence: CAPEX figures are stated with a tolerance of around ±20 per cent, the inspection is sample-based (for multi-family buildings typically around 10 per cent of the units) and non-destructive. Further reading: Technical Due Diligence — Contents, Depth, Report Structure.

Process & Duration

From Commissioning to Report: Realistic Timelines

How long a TDD takes depends on the depth of investigation — and equally on portfolio size, building class, construction year and the technical condition of the assets. Commissioning is followed by a lead time for data room setup and scheduling; the site inspection usually takes place on a single day. The delivery date for the report is agreed as binding at commissioning.

Red Flag TDD

Rapid initial assessment to identify show-stoppers — here, speed is of the essence. Report of 15 to 25 pages with traffic-light rating. Delivery shortly after the site inspection — with a binding date in bidding phases.

Full-Scope TDD

Complete investigation with a quantified CAPEX statement. Report of 40 to 80 pages structured by building elements and trades. Delivery time depends on asset size, construction year, condition and data quality — agreed as binding at commissioning.

Portfolio TDD

Multi-asset assessment with a risk-based sample (construction year, modernisation history, use type). Overall duration is project-specific — driven by the number of assets and the repetition factor of identical building types; in bidding processes the agreed deadline is binding.

Fees

What a TDD Costs — Fixed Price per Asset, on Request

The HOAI, Germany's official fee scale for architects and engineers, does not regulate Technical Due Diligence; fees are agreed freely, usually as a fixed price per asset. The fee depends on asset size, data quality, depth of investigation and time pressure — we quote fees on request.

Asset Size / Scope	Fee
Residential building up to 600 m² GFA — Red Flag TDD	on request
Residential building up to 600 m² GFA — full scope	on request
Multi-family / mixed-use up to 2,000 m² GFA — full scope	on request
Commercial asset above 2,000 m² GFA (office, retail, logistics)	on request
Portfolio TDD (multi-asset assessment)	on request
Optional: drone survey of roof/facade (external partner)	on request

Fees on request; agreed as a fixed price per asset, net plus statutory German VAT. Usual payment plan: 30% on commissioning, 30% at the site inspection, 40% on report handover.

For market context: standard investigations of single assets in Germany typically command fees of around €5,000 to €15,000 plus VAT; detailed or investment-grade investigations involving specialists (structural engineering, fire protection, hazardous materials) reach around €15,000 to €50,000 plus VAT, and more for large portfolios. Day rates of experienced TDD professionals in North Rhine-Westphalia typically range from around €900 to €1,400 plus VAT. Providers who state fixed prices before commissioning are the exception in this market — which is precisely the standard offered here.

Comparison

TDD, Market Valuation or Condition Assessment?

Three documents, three purposes — and three different recipients. Choosing the wrong format costs money or evidential value.

	Technical Due Diligence	Market Valuation (Verkehrswertgutachten)	Condition Assessment
Core question	What technical risks and investments does the asset entail?	What is the market value of the asset?	How do I manage maintenance and budget in the standing portfolio?
Legal / normative basis	RICS standard (TDD guidance note), AHO Booklet 21, DIN 276, DIN 31051, GEG	Section 194 BauGB (German Federal Building Code), ImmoWertV (German valuation ordinance)	DIN 31051, GEG, BKI cost benchmarks
Occasion	Acquisition, disposal, refinancing	Lending, tax, court, inheritance settlement	Budget planning, portfolio management, renovation strategy
Outcome	CAPEX plan with ranges, risk matrix, negotiation basis	Value in euros as at the valuation date	Prioritised measure and budget plan, traffic-light rating
Evidential value	Decision-making report — not forensic evidence	Court-proof given appropriate valuer qualification	Internal management instrument

Further reading: Market Valuation vs. Condition Assessment — Which Document for Which Purpose · CAPEX Planning for Residential Portfolios with BKI Benchmarks

From Practice

Anonymised Example: OBJ-2026-014-MFH

Full-scope TDD for a multi-family building with 38 residential units in Düsseldorf: report of 64 pages, CAPEX range of €1.42 to €1.84 million over 10 years, structured by DIN 276 cost groups with BKI cost benchmarks. The CAPEX tables were handed over as an Excel annex — directly compatible with the client's long-term budget planning.

Asset data anonymised using an internal project code scheme; plain-text addresses are never used in publications or AI-assisted workflows.

Every report is backed by hands-on experience from overseeing more than €70 million in investment volume and over 20,000 assessed residential units in the German housing industry.

Author: Mathias Ponitka, Architect AKNW · EU drone pilot A1/A3 Profile and qualifications

Frequently Asked Questions

TDD in Line with the RICS Standard — What Portfolio Holders Ask

How much does a Technical Due Diligence cost in Germany?

The fee is agreed as a fixed price per asset and depends on asset size, data quality and depth of investigation. We quote fees on request — after a brief description of the asset you receive a binding fixed-price offer.

How long does a Technical Due Diligence take?

Duration depends on the depth of investigation as well as portfolio size, building class, construction year and the technical condition of the assets. Commissioning is followed by a lead time for data room setup and scheduling; the site inspection usually takes place on a single day. The delivery date for the report is agreed as binding at commissioning — in bidding processes the fixed deadline applies.

Which standard governs the Technical Due Diligence?

The governing standard is the RICS guidance note Technical due diligence of commercial, industrial and residential property in continental Europe; AHO Booklet 21 (due diligence, 2006) serves as the complementary German reference, while cost and maintenance structures follow DIN 276 and DIN 31051. Work follows the MP four-phase TDD model with two process variants. A common misconception: TDD is not a scope of services defined in AHO Booklet 9 — Booklet 9 covers project management in the construction and real estate industry. AHO Booklet 21 addresses due diligence as a chapter on value optimisation of existing properties.

How does a TDD differ from a German market valuation?

The Technical Due Diligence assesses the technical condition of an asset and translates it into an investment plan (CAPEX) — it is a decision-making report for a transaction or portfolio strategy. A Verkehrswertgutachten determines the market value pursuant to Section 194 of the German Federal Building Code (BauGB) and the German valuation ordinance (ImmoWertV) and is used for lending, tax or court purposes. The two documents do not replace each other; in acquisitions they are frequently commissioned in parallel.

Is a TDD worthwhile without a specific acquisition?

Yes. Portfolio holders also commission the TDD methodology for refinancing, to prepare disposals (vendor due diligence) and as the starting point of a portfolio strategy: the CAPEX plan with remaining useful life per building element group is the data basis for long-term budget planning and the decarbonisation pathway required under the GEG, the German Buildings Energy Act. For ongoing asset management without a transaction context, a leaner condition assessment is usually the more appropriate format.

Does a TDD replace a hazardous materials or structural survey?

No. A TDD is a visual, sample-based inspection that flags suspected risks, for example suspected asbestos in buildings constructed between 1960 and 1993. Sampling and laboratory analysis (asbestos, mineral fibres, PAH, PCB), detailed structural calculations and in-depth building physics surveys are commissioned separately where required.

Overview of all B2B services on the Corporate Clients page.

Technical Due Diligence in Line with the RICS Standard