ᐅ Efflorescence on the base coat plaster at the front door

Hello everyone,
Efflorescence has appeared on the base plaster of our front door. I first noticed it about a week before Christmas. The pictures are from yesterday. Comparing the photos from December and yesterday, it seems to be getting worse.

The question is, what is causing this? This usually happens when water penetrates the insulation. But where is the water coming from? This is the east side of the house, which rarely gets driven rain. The roof overhang also protects this side quite well, and the area directly along the wall is almost never wet. There is almost always a strip about the width of the doormat that remains dry. The entrance platform also has a slight slope away from the house, so it doesn’t direct any water there.

This is the only spot on the house; everywhere else is fine.

Could this be some kind of condensation issue in the door frame? We had quite a bit of trouble with the front door – this is now the fourth (!!!) door leaf, and once the entire door frame was replaced. The old frame was cut off at the height of the entrance platform, the new one was installed and anchored anew. But everything actually looks sealed properly?!?

Does anyone have any ideas?

Thanks and best regards,

Andreas

Do you spread salt in winter? To me, this clearly looks like damage caused by de-icing salt.

Hello,

good idea, but no, we don’t use salt for spreading. Also, very little salt is generally applied here, so it’s rather unlikely that larger amounts of salt could have been brought in on the shoes.

Best regards,

Andreas

To me, it visually has something to do with the landing.

Depending on how it was made, it could still contain a lot of moisture that is now coming to the surface (I don’t know how old it is).

From what I can see, road salt is unlikely to be the cause...

That's correct. The efflorescence only appears where the platform is. Do you have any photos from the construction phase? Was concrete poured there, possibly directly against the house wall, meaning without a separating layer?

I need to look for some photos; the platform was built in September 2017. So it is now over 6 years old. By now, it should be dry... I can't say right now if there is a separation layer between the platform and the wall. Maybe something can still be seen in some pictures.

Best regards,

Andreas