fixtek Practice

Seven mistakes when fixing installation pipes, and how you avoid them

6 min read

Some mistakes in fixing pipes cost an afternoon of rework. Others lead to water damage or to rejected work at handover. These are seven mistakes that often occur in practice, what they cost and how you avoid them.

1. An anchor that does not suit the base material

An expansion anchor in the hollow core of a hollow-core slab floor. An anchor for non-cracked concrete in a tension zone where the concrete can be cracked. The anchor goes in, but it does not hold what it must hold.

What it costs: a pipe that comes loose, with water damage and a complete reinstallation.

How to avoid it: first establish what the base material is: solid concrete, cracked or non-cracked, hollow-core slab, masonry or steel. Choose the anchor on that basis and check in the ETA which base material it is approved for.

2. Too much spacing between the clamps

The clamps are further apart than the standard or the pipe manufacturer allows. The pipe sags, stress builds up on the couplings and in the long run something starts to leak.

What it costs: leaks and rework. On a sprinkler system, rejection at the inspection.

How to avoid it: use the spacing from the standard that applies to the project, such as NEN-EN 12845 for sprinkler work, and the data from the pipe manufacturer. If in doubt, add an extra clamp.

3. No allowance for expansion

Hot and cold pipes expand and shrink. If every clamp is fixed, the stress builds up until a coupling or connection fails.

What it costs: leaking couplings, creaking pipes and material fatigue.

How to avoid it: combine fixed points with sliding points. A fixed point, such as the FSFP, guides the expansion. A slider, such as the FASM or FASH, lets the pipe move along its length.

4. Unapproved material where an approval is required

An ordinary clamp and a random anchor under a sprinkler pipe. The pipe hangs, but the work is rejected at the inspection.

What it costs: dismantling, reinstalling with approved material and a new inspection.

How to avoid it: on sprinkler work, use clamps with the approval that the standard requires, such as FM, VdS or UL, and anchors with an ETA. In an FM system, the rule is: if an FM approval exists for that component, use the FM Approved component. Where a fire rating applies, you choose products with fire data. Keep the certificates in the project file.

5. An anchor set wrongly

Drilled too shallow, the wrong drill diameter, a hammerset anchor that is not fully expanded, or a bolt anchor that is not tightened to the correct torque. The anchor seems to be firm, but it does not reach the values in the ETA.

What it costs: an anchor that pulls out under load. In the best case rework, in the worst case damage or injury.

How to avoid it: follow the installation instructions of the anchor. Drill diameter, drill hole depth, drill hole cleaning, setting tool and torque differ per type. For example, you set the FAZ II Plus without drill hole cleaning, but with a torque wrench: at the specified torque, the anchor is set as the approval requires. For hammerset anchors, you use the specified setting tool.

6. A sprinkler pipe on profiled steel sheet

A profiled roof sheet is not designed for the weight of a filled sprinkler pipe. What you may hang from it is set by the standard and the design.

What it costs: rejection at the inspection and all clamps again, this time on the load-bearing structure.

How to avoid it: hang the pipe from the load-bearing structure, with a beam clamp such as the TKL or, on sloping beams, the TKLG. For lighter pipes, there are hangers that are approved for trapezoidal sheet, such as the TZ and the KDS. Check the permitted load and the approval for each size.

7. No documentation

The work is finished and everything hangs well. But no ETA numbers are recorded, no photos are taken and no certificates are kept. The inspector cannot establish what was used.

What it costs: delay at handover, extra inspections and in the worst case opening up what is already concealed.

How to avoid it: make documentation part of the work. For each fixing, record the product and the ETA or certificate number, take photos before anything is concealed and keep everything in one project file. For projects under the Wet kwaliteitsborging (Quality Assurance for Building Act), this is mandatory.

It starts with the preparation

Almost all of these mistakes happen before installation: the wrong anchor chosen, the spacing not checked, the documentation forgotten. Not sure which product you need? Describe your situation in the Product finder.

This article is general information, not design advice. The text was checked on 21 October 2026 against the sources below. The design of your installation and the certifying body decide what applies in your project.

Sources

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