Measures due to damp basement - differing expert opinions

Good evening,

today is my first post, the renovation of our approximately 100-year-old house is becoming concrete!

One issue is the damp basement. The basement is intended to be used as a hobby room, workshop, laundry room, and prospectively for an additional bathroom. Both the exterior walls and interior walls are affected. We now have three opinions:

1. The expert before the purchase recommended that we carry out an external waterproofing. Especially since the house is relatively accessible all around. The moisture is not only detrimental to its use but also endangers the substance of the masonry in the long term.

2. A specialist company recommends creating a horizontal barrier at the basement floor by injection and additionally injecting a surface barrier on all damp walls up to the ground level. Then applying a "special plaster" on top. They emphasize that the wall can continue to breathe with this method.

3. Another specialist company recommends providing the basement walls with an internal waterproofing, additionally injecting a horizontal barrier at ground level (approximately 1.6 m in the basement), and installing a cove at the bottom. External waterproofing is optional. The still damp masonry is not a problem—and they refer to Vendig in this context.

Now I am a bit puzzled, house construction is not my area of expertise ;-)

Regarding 1.: here I wonder how rising moisture from below, especially with the interior walls, is supposed to be prevented. Although I cannot assess whether the moisture seeps in more from the side.

Regarding 2: this sounds the most plausible to me.

Regarding 3: I have no good feeling about the still damp masonry.

Do you have any experiences or (further) opinions?

Best regards,

Simon

If you have the opportunity, I would do a combination of 1 and 2, meaning excavate and seal from the outside and install a horizontal barrier on the inside at the floor level (whether driven, cut, or injected is probably a matter of belief).
Fillet to the floor slab and coat the floor slab with a sealing slurry up to the horizontal barrier. Otherwise, you have dry walls but wet feet.

I would worry less about stability, otherwise many old buildings would have already collapsed.

With Rajasil, for example, you can download a brochure with detailed drawings from the website.

It would then look something like this (c) wall-systems

"Breathing walls" - the old topic: There are no breathing walls, at least with regard to the exchange of humidity. At most, the wall plaster can absorb moisture and release it again. But before even 10ml of water has been "breathed" from inside to outside, a few generations have passed.

Basically, it is of course still sensible to do something here, with sealing on the outside and a horizontal barrier, as wrote. However, I can only report from our cellar (100 years old, rammed earth + brick) that moisture repeatedly condenses on the floor and/or slightly penetrates from below in very wet seasons. You won’t get that under control without lifting once and sealing also from below. ;) In other words: With such an old gem, you will practically never completely get rid of the moisture in the cellar – or only with enormous financial effort. Which, in my view, also argues against #3 – an interior seal: in the end, that just causes more problems because you don’t see anything anymore – but the moisture is still there. Then I would rather check whether the foundation is still alright.

As for the bathroom, I am skeptical, but in my opinion, the hobby room and workshop are feasible with the measures mentioned.

Our house from 1921 has a damp cellar. That was how it was intended back then. Although I wouldn’t call it damp, it is manageable. It’s perfect for storing food. For a workshop, etc., it’s also completely sufficient. I still have my laundry room in there. We also have a shower in there from the previous owner, but nobody uses it; somehow that kind of cellar is not an environment for wellness. But we have also thought about what could be done. Neighbors had metal sheets driven in as a horizontal barrier many years ago and are satisfied. But all methods have advantages and disadvantages. I also rather don’t believe in a structural problem, otherwise, practically all old houses would have already collapsed. If we ever have the money, we would excavate all around the outside, seal it, and additionally install a horizontal barrier. However, the floor slab or rather the natural ground beneath the houses will not become watertight from that. We have a vaulted cellar, and on the columns, you can see that moisture rises on the first approximately 50 centimeters. There is nothing you can do about that, except perhaps apply new restoration plaster every few years.