GAEB: formats, exchange phases and practice in construction

GAEB is the German standard for the electronic exchange of bills of quantities (Leistungsverzeichnis, LV) in construction. The acronym stands for "Gemeinsamer Ausschuss Elektronik im Bauwesen" (Joint Committee for Electronics in Construction), the body that defines the standard. A GAEB file contains a bill of quantities with item numbers, texts, quantities and, where relevant, prices, in a structure that tendering, estimating and procurement software can import without retyping.

What is GAEB?

The Gemeinsamer Ausschuss Elektronik im Bauwesen is a committee in which public clients, the construction industry and planners jointly develop rules for handling construction work electronically. Its best-known output is the data exchange standard, which defines how a bill of quantities is structured and passed between the parties.

The value lies in the structure. Every item has a unique item number (Ordnungszahl, OZ), a short and a long text, a quantity and a unit. When a company bids on a GAEB file, these item numbers are preserved, so bids can be compared line by line without anyone mapping rows by hand.

GAEB formats: GAEB 90, GAEB 2000 and GAEB DA XML

The digits in the extension indicate the exchange phase, the letter before them the format. An .X83 is therefore a request for bids in XML format; a .D83 is the same phase in the old GAEB 90 format.

The exchange phases

Each phase represents one step in a tender:

There are further phases, including ones for quantity determination and billing, as well as separate trade phases for price requests and orders with building-material merchants. Which of them your software supports is stated in its documentation.

How a bill of quantities flows between planner, contractor and supplier

A typical sequence on a building project:

1. Planner → contractor: the architect or engineering firm prepares the BoQ and sends it to bidders as an X83.
2. Contractor estimates: the estimating team imports the X83 and works out unit prices. For the material share it needs supplier prices.
3. Contractor → suppliers: material packages are built from the BoQ and sent as requests to merchants and manufacturers, ideally again as X83 or a structured list.
4. Suppliers → contractor: bids come back, at best as X84, often as PDF or Excel. They feed into a bid comparison (Preisspiegel).
5. Contractor → client: the bid goes back as X84, possibly with alternative bids (X85).
6. Award: the award is sent as X86 and is the basis for ordering and billing.

The break usually happens at step 4: the planner delivers clean GAEB, but many suppliers reply with PDFs in their own structure. That is where manual work begins.

Example: items in an X83 and X84

Item number, text, quantity and unit are identical in both files. The X84 only adds unit and total prices, which is why several X84 bids can be placed side by side directly.

Common mistakes with GAEB

• Changing item numbers. Renumbering or merging items breaks the link to the original BoQ.
• Sending the wrong phase. Sending an X84 instead of an X83 to suppliers reveals your own prices.
• Ignoring long texts. The decisive requirements are often in the long text, not the short text.
• Converting old formats unchecked. Information can get lost when converting from GAEB 90.
• Retyping supplier bids. Transferring PDFs into the estimate by hand risks transposed digits exactly where it gets expensive.

How Streckenheld helps

Streckenheld accepts bills of quantities as PDF, GAEB or Excel; accepted formats include X83, X84 and XPWE. GAEB DA XML files are parsed exactly in code, without OCR, so item numbers, quantities and units stay unchanged. The AI extracts and assesses the BoQ and spots gaps and likely claim traps. Supplier bids as PDF or X84 are mapped to the items. Exports are available as GAEB X83 (without prices) and X84 (with prices); budget estimates from the BoQ can be downloaded as CSV, XLSX or GAEB.

Learn more in the guides on BoQ analysis, budget estimates from the BoQ and RFQ preparation.