ᐅ Crack in the External Insulation – Potential Issue with Water or Moisture?

Good evening dear experts,

I have a crack in the external insulation, which was obviously caused by the attachment of the rain gutter – the crack is about 30-40 cm long (12-16 inches).

I have a few questions:

- Is this purely a cosmetic issue, or can water or moisture penetrate the crack, potentially causing mold or further damage to the external insulation? Opinions online seem to vary quite a bit.

- If I want to fix it – what would be the best method? Filling it with filler (which type?)? I am concerned that the crack might be too narrow to properly press filler in. If this is done – should it be done now in winter or would it be better to wait until spring or summer?

- Or would it be easiest to simply apply exterior paint over it repeatedly until the crack is no longer visible?

While we’re at it – are there general recommendations for how often the exterior paint should be renewed (10, 15, 20 years, etc.)?

Thank you in advance and

Best regards.

My advice, even if it might be harmless—which I don’t know—you keep looking at it, it annoys you and keeps circling in your mind. So get rid of it. How? Use a Dremel to open it slightly, then get a cartridge of Sikaflex or a similar product, apply it to seal the area, and then paint over the Sikaflex. Be careful: not silicone, as it can’t be painted over. Not acrylic, because it’s not waterproof. Also, don’t use products like Moltofill, since it’s on the outside. Karsten

Good evening Karsten,

thank you. How can one determine whether the crack is concerning or not?

By not repainting, do you mean not using the actual exterior paint color? Wouldn't that make it even more noticeable visually?

When is the best time to do this – now or in spring or summer?

PS: What do the others think?

Sikaflex
Naturally paintable, which is why Sika is used. Sika is a polyurethane. Silicone would not be suitable because it cannot be painted over.
Whether it is necessary or not doesn’t matter, as sealing it does no harm and can only be beneficial.

Ok, thanks. Last question – should we do it now or wait until spring or summer?

It is important that the wall is dry, so it is better to apply the material in spring when the sun has been shining on it. Polyurethane can basically be applied at temperatures above a few degrees Celsius (a few degrees Fahrenheit). However, it then takes about two weeks for a 1cm (0.4 inch) thick seam to fully cure.