Anchors and fixings: substrate, ETA and proof for tradespeople

Why anchor damage becomes so expensive

Anchors rarely fail immediately. They fail when load, drill hole or substrate do not match: a suspended ceiling falls, a facade cladding comes loose, a handrail or balustrade gives way. Then it is not a minor defect but personal injury and liability. That is why fixing safety-relevant components is one of the works where proof and documentation count.

Step 1: determine the substrate

Before you choose an anchor:

• Read the plan: Which component, which building materials, what thickness?
• Note drilling dust and drilling behaviour (indications, not a substitute for determination).
• Concrete: cracked or uncracked? Strength class? The ETA distinguishes between them.
• Masonry: solid brick, hollow brick, aerated concrete, sand-lime brick. The characteristic load capacities in the ETA apply only to the bricks named there.
• Joint and mortar bed: is the drill hole in a mortar joint or in the brick? This changes the value.

For masonry made of other, comparable bricks, the technical rules allow the load capacity to be determined by site tests.

Step 2: type of anchor and proof

The Technical Building Rule (MVV TB) states for anchoring in masonry: the anchorages are to be designed by an engineer, verifiable construction drawings are to be prepared, and the provisions of the relevant ETA are to be observed, in particular on anchoring substrate, strength class, joint execution, minimum component thickness, minimum axial and edge distances, temperature limits and drilling method.

Step 3: execution according to the instructions

The manufacturer specifies in the installation instructions:

1. Drilling method (hammer or impact drilling, drilling without impact).
2. Drill diameter and drill hole depth.
3. Cleaning the drill hole (decisive for injection and bonded anchors).
4. Setting and tightening (torque for heavy-duty anchors).
5. Minimum distances to edges and from each other.
6. Curing time for mortar, temperature range.

Do not deviate. An oversized drill hole or an uncleaned drill hole destroys the load capacity.

Step 4: document and check

For safety-relevant fixings, document:

• Which anchor (type, batch, ETA number) was set where,
• substrate and component thickness,
• drill diameter, depth, cleaning,
• photos of the setting process,
• if required, pull-out tests on site with a record,
• approval by the designer or structural engineer.

If the plan is missing or questionable

If it remains unclear which load acts, which substrate is present or which fixing is meant, notify this in writing (see Bedenkenanmeldung). Request the design calculation or planning before you install. If the client instructs it anyway, record what the client demands and carry out only what you can answer for professionally.

This applies especially to fall protection, balustrades, facades and suspended ceilings.

Typical mistakes

• Wrong anchor for the substrate (plastic anchor in aerated concrete without a suitable approval).
• Edge and axial distances too small.
• Drill hole not cleaned with injection or bonded anchors.
• Impact drilling in hollow brick, where drilling must be done without impact.
• Load assumptions estimated instead of calculated.
• No documentation, so in the event of damage the proof is missing.
• Mixed use: anchors from different manufacturers with unsuitable screws.

Frequently asked questions

Sources and status

• MVV TB (Model Administrative Provision Technical Building Rules) 2025/1, technical rules on anchoring in concrete and masonry (checked against the text in the BauWalker corpus)
• § 4 para. 3 and § 13 para. 3 VOB/B
• DIN EN 1992-4 and the relevant ETA/EAD: not checked word for word here.
• Stand: 19.10.2026. This article does not replace a design calculation. Load capacity and suitability in an individual case are determined by the designer.
• Quotations of statutory text are given in translation; the German wording is authoritative.