ᐅ Waterproofing a basement wall from the inside to prevent external water infiltration. What are the possible solutions?

Hello everyone,

I need your expert advice and already want to say: thank you very much!

The problem:
One of the basement’s exterior walls (sand-lime brick) has become leaky over the years, and during rain (especially heavy and prolonged rainfall), water seeps through the wall from the outside. Exterior insulation is only partially possible because the neighbor’s garage partially adjoins the exterior wall, so excavation there is not feasible. Therefore, the wall now needs to be waterproofed from the inside.

The question:
What is the best way to waterproof from the inside?
Some suggest using silicate panels on the inside, as they absorb moisture during rain and release it back out when it is dry.
Others recommend using waterproof slurry (tanking slurry) combined with an insulation layer and the masonry wall, preventing any water from getting through during rain.
Which solution is better?
And what are the disadvantages of each approach?

Your solution:
?

Thank you very much and have a nice evening!
Schubbiano

Nothing works from the inside. The water will rise by capillary action. However, calcium silicate boards are a good initial choice. The wall must have permanent airflow from the inside unless you stop the water supply and then dry it using mechanical means.

Best regards
Gabriele

Thank you, Gabriele!
Are there any other opinions or recommendations?
Thanks!

Injection methods using water glass are usually the preferred solution.
Applying something on the inside won’t solve the problem.
Where you can access it, I would also seal it from the outside.

Just thinking logically: if water penetrates the wall and is only stopped at the inner surface facing the room, it becomes trapped inside the wall instead of coming back into the room and evaporating or being drained away somehow. This way, you’re essentially sealing the water inside the wall, turning it into a sponge. The water will then try to leave again and may spread to adjacent areas once the “sponge” is fully saturated. Whether it’s hard to access or not, water ingress must be stopped "at the source," otherwise the wall will start to rot. Simply suppressing efflorescence on the inner surface won’t dry out the wall; it will remain damp and will effectively radiate moisture, even if it no longer appears in the form of droplets. Find the point of entry – it is probably at the junction between the neighbor’s garage roof and your house wall (and likely causes similar damage inside their garage). Could the drainage from the neighbor’s garage roof be clogged?
A reading suggestion would be: https://www.hausbau-forum.de/threads/nachbar-baut-haus-an-garage-nachbars-wand-ist-nass.35530/

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Nothing else!!!
Find and fix the cause.......outside!!!