ᐅ Mineral plaster on the house not applied flat, but with a convex, bulging shape

Hello everyone,
we are having a mineral plaster applied to our house (system: external thermal insulation composite system, ETICS) and yesterday the plaster was applied (the reinforcing mesh was applied the day before), and corner protection profiles were installed at doors and windows beforehand.
Yesterday, just for fun, we placed a straightedge horizontally on the plaster. The resting points were, for example, the corner protection profiles between two windows.
We noticed that the plaster is not flat but bulging, meaning that the plaster surface is not flush with the straightedge. In some areas, it is about 1 to 2 cm (0.4 to 0.8 inches) or more thinner.

So the question is: how is this with you? Is this normal? Is there an acceptable tolerance range? I’m not sure if maybe another layer will be applied today, but I can’t really imagine that.

With the naked eye, you wouldn’t notice it, but now that we’re aware...

Tommes78 schrieb:
Hello everyone,
we are having a mineral plaster applied to our house (construction: ETICS) and yesterday the plaster was applied (the reinforcing layer was done the day before), and prior to that, corner protection strips were installed on the doors and windows.

Actually, the reinforcing layer should dry completely first, which takes about 3 days depending on weather and layer thickness.
Before plastering, a primer coat still needs to be applied.

Yesterday, just for fun, we placed a straightedge horizontally on the plaster. The contact points were, for example, the corner protection strips between two windows.
We noticed that the plaster is not flat but bulging, meaning the plaster is not flush with the straightedge and there are spots where it is missing by about 1 - 2 cm (0.4 - 0.8 inches) or more.

Instead of a straightedge, use a screed board or a long spirit level.

So my question is, how is it for you? Is this normal? Is there an acceptable tolerance range? I don’t know, maybe another coat will be applied today, but I doubt that?!?

With the naked eye, you wouldn’t see it, but now that we know...

Certain tolerances are normal on construction sites.
Unevenness usually becomes noticeable only when the wall is lit from the side. For example, if you want to install lights under the eaves, the wall might not look perfectly smooth in the evening.

As with everything, proper preparation before plastering is essential.
To reduce unevenness from the start, it is advisable to order ETICS boards with tongue and groove edges.
After bonding, fill all joints with expanding foam.
Then use a long spirit level (e.g., 2 m (6.5 ft)) and a sanding block to sand down any bulges.
Next, apply the reinforcing layer, remove excess material with a notched trowel, embed the mesh (pay attention to overlapping, minimum 10 cm (4 inches)),
and very importantly, first use a brush to even out dents before smoothing with a straightedge.

If the wall is properly prepared, not much can go wrong during plastering.
Apply plaster with any preferred grain size, remove excess with a notched trowel, then smooth with a plastic or sponge float.

And don’t forget to paint.

Thank you for your detailed response regarding the execution, but unfortunately, it doesn’t help me much in this case.....

The reinforcement and plaster are already applied and are scheduled to be painted next week. The question is:

a) Is this normal (I rather don’t think so)?
b) Are there any tolerances (is up to 1 cm (0.4 inches) acceptable)?
c) What can be done if it stays as it is now?

As far as I understand, unevenness should have been evened out beforehand by the reinforcement layer, right?

I’ve discussed this with the site manager. He wants to take a look but I think he will say it’s within tolerance. That’s why I wanted to ask for opinions and look for solutions on what can be done.

The question is more whether you actually notice it – house construction isn’t precision engineering. Just think about how some areas of interior plaster look. Most people simply don’t notice...

A more important question would be about the lighting, because that really reveals a lot... although it’s not necessarily a crooked wall, but more like bumps or unevenness.

We used scratch render, which is always scratched across the entire surface... at least in theory.

Where he’s right: there was very little drying time between the two layers – that can cause problems later on. Especially since the temperature was actually too warm for this kind of work...

@Sebastian79 - I agree with you on whether it will even be noticeable. There will be lights outside anyway, so I have a bad feeling about it...

As I said, I didn’t notice it just by looking, only when I checked it for fun.

I understand that there are tolerances, but what exactly are they? In one spot it’s 1cm (0.4 inches), in another 2cm (0.8 inches), and so on...

Well, I’ll wait for the project manager’s response...

Tommes78 schrieb:
Are there any tolerances (up to 1 cm (0.4 inches) acceptable)?

Possibly in DIN 13345, otherwise tolerances for building construction are generally specified in DIN 18201 and DIN 18202.

Maybe you could try placing a straightedge on a few other houses to get a sense of this.