STEP 7: What to do when a wall plug does not hold?
During Michno System installation, a plug may sometimes fail to grip properly, especially in older buildings or mixed substrates. This guide explains how to identify the problem, choose the right plug and safely continue installation.
During Michno System installation, most holes hold firmly after the first screw-in. However, on every construction site there may be a situation where the wall plug does not grip as it should — especially in older buildings, where walls can be unpredictable.
In this step, we show how to identify the problem and how to choose the right fixing so that the structure remains durable and safe.
Why does a wall plug sometimes become loose?
Substrates are not all the same. Even within one wall, you may come across areas with different density and hardness.
The most common causes of poor holding are:
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hitting a joint between hollow blocks or bricks – it contains more lime and sand than cement, so it is soft,
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old walls – with loose binder, leaky joints and often dusty material,
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hollow blocks and perforated bricks – where the drill bit falls into voids,
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excessive speed or hammer drilling – these can “break out” the hole and enlarge its diameter.
As a result, the wall plug does not expand properly in the hole and the screw spins in place.
Step 1: Replace the wall plug with a larger size
If, after screwing in, the profile “moves” in the hole, there is no point trying to tighten it further – it will not grip anyway.
Instead:
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Remove the wall plug.
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Use a larger size, e.g. RawlPlug UNO-10. The profiles have a screw with a diameter of 6 mm, so they can be used with this plug.
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Carefully deepen the hole with the same drill bit, without hammer action.
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Insert the new plug and screw the disc in again.
This simple solution allows you to save every “weak” point without chiselling the wall.
Step 3: Alternative solutions for difficult walls
If you are dealing with a very weak wall, for example old lime mortar or crumbling joints:
• in extreme cases, you can use chemical/resin anchors – they provide very strong anchoring,
• you can also move the drilling point a few centimetres to the side, avoiding the weak area.
If the wall is very old, sometimes moving just 2 cm is enough to hit brick instead of a joint – the difference in load-bearing capacity can be huge.
Step 4: Prepare an emergency kit
An experienced contractor always carries an “emergency kit” with wall plugs of different diameters.
Having just a few larger plugs is enough to finish the installation without interruptions or improvisation.
Step 5: How to avoid problems in the future
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Set the drill to a lower speed – too much speed can “burn out” the hole.
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Do not use hammer drilling in ceramic hollow blocks – use non-hammer mode.
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Do not overheat the drill bit – an overheated bit can vibrate and enlarge the hole.
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Match the type of drill bit to the substrate you are working with.
