Renovate outer wall/retaining wall (plaster crumbling / wall covering)

Hello everyone,

when we built our house 6 years ago, a low retaining wall was constructed along our driveway adjacent to the sidewalk. The wall was plastered white at the time, and for the wall cap we cut granite slabs that we still had left over from the entrance platform. According to building regulations, we had to leave a distance of 10 cm between the wall and the sidewalk, so a "dirt gap" was created here. This was casually lined with some bubble foil, and I tried to plant the gap with a few cushion plants. Unfortunately, the plaster started to crumble after a short time. We complained to the landscaper about this, and he reapplied the plaster, but that didn’t hold either. Shortly thereafter, the wall cap stones also came loose. By now, the landscaping company no longer exists...

Anyway, this is how our wall looks now:




For better understanding: The front part of the wall (about 7 meters) is "exposed," and in the rear part, we built a carport about 2 years ago. Interestingly, the plaster only crumbles on the front part; where the carport is, the plaster is still intact. Luckily, because I can’t even get to the wall there anymore.

On the back side of the carport, there is a staircase, and here you can also see a section of the wall where the plaster is already crumbling in places.

So I need tips on how best to repair the damage and prevent future damage.

[*]How can I better protect the wall from moisture?
[*]Do I need to renew/replace the wall cap?
[*]Do I need to waterproof or prepare the wall underneath the cap beforehand?
[*]What should I do with the sparsely planted "dirt gap"? Concrete it over? I find it much friendlier with plants. However, a lot of weeds grow there and cigarette butts and candy wrappers end up in the gap – so it’s not ideal.
[*]And how can I best renew or repair the plaster?
[*]Does it make sense to apply new plaster again, or should I rather brick the wall in the exposed area?
[*]Do I need to use a special substrate here or a special adhesive for the bricks/cladding as moisture protection?
[*](And a totally dumb question: How can I neatly separate the old plaster where the carport begins?)

Lots of questions – but I’d really like to solve this troublesome issue; I see this "eyesore wall" every day, and that sight certainly doesn’t match my idea of a new build...

Thanks in advance for all the helpful and further tips!

Anghi

Well, presumably the wall is wet. If the moisture comes from below, the foundation was executed incorrectly and/or no waterproofing against the ground was done. Just Google Horizontalsperre. Either (expensive) renovation or demolition and a complete rebuild.
It would be “better” if only the plaster was poorly applied. Then a rotary hammer with a chisel helps to remove the old plaster (straight cut to the carport with a cutting disc and then chisel, possibly by hand). However, the affected coping stones also rather suggest that the whole wall is wet :-/ Or they were coincidentally also poorly executed and did not withstand the frost.

In the pictures, you can see that the moisture comes from the joint seams of the granite slabs; silicone or a sealing compound should have been applied there.

Hello Anghi

the whole thing is a botch job. You caught a landscaper who paid 20 euros to be recognized as a company. Had no idea. There are many like that.

Steven

Hello again and sorry that I haven’t gotten back to you for so long. Many thanks also for your assessment. Meanwhile, I had a landscaper here again who looked at the wall and basically confirmed TomTom79’s suspicion: the main cause is likely the unsuitable and poorly installed wall cap stones. However, he gave us the tip that a plasterer should take another look at it – building the wall and plastering the wall are two different trades (the landscaper did both himself last time...). We now have an offer for new wall cap stones and will still ask a plasterer about the plaster. I originally wanted to do it myself, but I’m really not confident enough to tackle it...

I’ve already noticed that we got stuck with a botcher. That insight doesn’t help me much though. This is a new development area, meaning that more or less everyone is building at the same time and all craftsmen are fully booked. It’s luck just to get a landscaper who still has an available appointment. And if you also get one recommended by the neighbor, you would think he actually knows his trade.

Tearing down the wall is out of the question. At least where the horizontal barrier is concerned, I’m sure it was done correctly. The wall in the "raw state" was/is flawless. The foil on the back (at my "planting trench") was not laid cleanly, the cap stones are rubbish (not cut cleanly, no drip groove, not glued properly), and the plaster was also not done properly. But these should all be defects that can still be fixed afterwards.

If I had to tear down the wall, I would have to remove the carport, partially repave the driveway, take the risk that the adjacent sidewalk (property of the city) would be damaged during the demolition work, ... Sorry, but that is way too risky, too complicated, and too expensive for me. And all just because the plaster is crumbling... At the moment it is primarily a cosmetic problem (which I wanted to try to fix with a suitable workaround). There is no indication that the wall will no longer serve its purpose – namely to support the terrain – in the foreseeable future. For that reason, I would like to keep things in perspective...

Nevertheless, thanks for all the tips and assessments!

What kind of cover plates do you have planned now? I find most of them quite ugly, so it will probably be natural stone, despite the costs. If the plaster problem is not easy to solve, but the wall is professionally sound, you could also consider a cladding made of boards. That would also fit the carport.