ᐅ How does water get into the basement?

Hello,

We started building in January 2022 with an architect who was also responsible for the planning and construction management.
My wife and I were beginners when it came to house construction, so we had to rely on others.
The new building has been standing since around July 17, 2023, and we moved in on July 22.

Despite repeatedly requesting a waterproof concrete shell (white tank) due to the property being on a slope/hillside, this was never done.

My parents’ house is just two streets away, so I was familiar with the concept of a waterproof concrete shell.

The architect’s exact words:

“I have built several houses there, and it was never necessary.”

And even with a waterproof concrete shell, the current problem probably could not have been prevented.

We now experience water entering the basement through the side of the granny flat during very heavy rain. The walls are damp (Trotec moisture meter available), and mold and similar issues are starting to develop!

There is drainage on both sides of the granny flat side.
During the shell construction phase, I already had the basement flooded twice after heavy rainfall:
December 25, 2022, and January 16, 2023.

At the time, I repeatedly pointed out to please check the drainage system.
Anyone who has pumped out a basement (partially below ground level) twice knows what an enormous amount of work that is and will appreciate a submersible pump from that day on.

The architect, contractors, and others have unfortunately not been able to identify the exact cause, so it is not possible to determine which trade is responsible and must carry out the repair. This means we have to pay upfront again, and in the worst case, it might be a trade that does not have the money to fix the issue. We are three people, and our second child is on the way. If this continues, I fear we might have to declare personal bankruptcy in a few months and lose everything.
You borrow so much money to build a house and get a leaky basement as a thank you.

The worst part is that you can’t do anything yourself and feel completely powerless while the trades blame each other.

That’s the story of the new build.

I have not been able to enjoy the house for weeks and now deeply regret having built it.

I am open to any suggestions.
A leak detection company has already been on-site (at our expense) and only confirmed that water is coming in but could not determine how.

In other words, the cause remains unknown.

I have now reached a point where I do not rule out legal action if there is no other solution. We took out a ÖRAG homeowners insurance before construction began, as well as natural hazard insurance since we are on a slope/hillside.

How was the basement waterproofed? Maybe upload a cross-section.
What was the recommendation regarding the building waterproofing in the report?

Do you have an inspection chamber for the drainage system? First, check if there is water standing in the drainage.

Phoenix1985 schrieb:

Water from very heavy rain entering the basement through the side of the granny flat.

Have you ever walked around your house during heavy rain to check where the water is coming from and where it drains? Where does your roof drain to?
You don’t want your basement to act as the drain for the slope.
Or is there no surface water during heavy rain?

There is currently a related topic here: https://www.hausbau-forum.de/threads/erheblicher-wasserschaden-im-neubau-doch-wodurch.46610/

You might find some useful ideas there.

Cronos86 schrieb:

How was the basement waterproofed? Maybe you could upload a cross-section drawing.
What was the recommendation in the expert report regarding the building’s waterproofing?

Do you have an inspection chamber for the drainage system? First, check if there is water in the drainage.

As a layperson, I understood that it’s a tanking system (“black tank”) rather than a “white tank.”

What exactly do you mean by cross-section? I’m currently away for work and can’t upload anything.

Regarding the expert report, isn’t it something you need to commission yourself?

We relied on the architect, who has demonstrably supervised five other houses during construction in this area before us.
I need to confirm about the inspection chamber for the drainage, but I believe we do have one.
According to the site supervisor for the shell construction, there was no water in the drainage. The landscaping is not finished yet, and rainwater flows down from the hill above onto the property. During heavy rain, water accumulates above the edge of the basement apartment.
I’ll check if I have a photo of this.

By "section," I mean a cross-sectional drawing of the house showing both the slope and the building. A detailed drawing of the basement plinth, illustrating the wall construction, is also helpful. This allows you to see what was done and where the problem might be.

There should be no standing water directly next to the house. The crawl space of the basement should be backfilled with well-draining material to allow rainwater to be directed towards the drainage system.

Today, a soil report is practically essential. It provides a written record of all the considerations necessary for the foundation. Even if the architect has experience building in the area, soil conditions can vary on a very small scale.

It is also possible that the architect has already made the same mistake five times... and just got lucky until now...