Basement walls wet - how to seal

Hey community,

can someone please tell me how I can waterproof basement walls (foundation) so that no groundwater penetrates.

Attempts have already been made to make the basement walls thicker => moisture still comes through the walls and now also through the floor (old building) - rubble stone walls are about 0.5 - 1.8 meters high wet.

It all started when the neighbor, who recently moved in, raised his garden by about an average of 1 meter.

Thank you in advance for your answers - I’m afraid a three-story house will collapse...

Hello,

attempts have already been made to make the basement walls thicker => moisture still comes through the walls and now also through the floor (old building) - rubble stone walls are about 0.5 - 1.8 meters high wet.

it all started when the neighbor, who just moved in, raised his garden by an average of about 1 meter.

I am very sure that you will not get any further without professional advice. Professional advice in such a way that an expert inspects the situation on site and then explains to you which form of sealing/taping you need to carry out.

It is probably safe to assume that you will have to expose the exterior basement walls (detached or semi-detached house?). Depending on the soil condition and the existing building material, the expert can then tell you which measures need to be taken in which order. The DIN specifies various forms of taping.

Sealing the floor slab will probably be somewhat trickier, at least it will reduce the clear room height since it has to be done from above. I can think of quite a few solutions here, but on the other hand — as with new construction — everywhere it depends. Each construction project must be considered individually, and it would be unhelpful if I gave you one measure knowing that there are others which can permanently keep out the penetrating water!

Someone MUST come out and examine the situation on site. Only in this way can you be sure to take the right — and permanently successful — measures. Regardless of whether you can perform them yourself or need a specialist company.

Rhineland regards

Hello Miki,

without guarantee/claim to completeness or correctness:

I have the same problem in my old building and also rubble stone walls, where we clearly have damp but not wet walls. If water drips/runs into your basement, the following suggestion will probably be useless:

We achieved good results without excavation outside by drilling holes inside the corresponding walls about 25-30cm above the floor and between the drill holes with a large drill bit at an angle downwards (about 30°).

Then so-called Verkieseler is filled into these holes, which is thinner than water and crystallizes upon contact with water, sealing the gaps between the stones. You then always check how much Verkieseler goes in (slowly seeps into the wall) and keep pouring until the Verkieseler stands in the drill hole, meaning the wall no longer absorbs anything. Quite a lot goes in and you have to drill many holes. It should also be done/supervised by someone who has done it before.

The result is not perfect but much better than before (now 4 years ago), but in the long term, we will also not avoid at least exposing one wall (in our case the driveway, but basically the same problem as your neighbor’s garden).

Costs of the operation including labor (own effort, anyone can drill holes) and Verkieseler about 2-3k€. Excavating everything from outside would certainly have cost us ten times as much.

Some places we would need to repeat it now, but some walls have been completely dry since then.

Addition on the topic of sealing the floor slab: in our case, it is such that previously (year of construction 1918), they first built the rubble stone walls and then inside inserted the floor slab (if at all), i.e., the walls do not rest on the floor slab but on soil/gravel or similar. That may also be the case with you, and if that is the weak point (which I do not suspect from your description), it must be solved differently.

Best regards
Dirk Grafe

Thank you very much for the two answers.

I thought I could come up with some kind of magic to uncover around it.
Well then. I guess I have to roll up my sleeves and get to work.

Can anyone possibly tell me how high the risk of collapse is with damp basement walls... so nothing is dripping, the sand between the stones is so damp that it can be rubbed off.

It is not my area of expertise, but one should keep away from unplanned excavation without professional (and liability) planning.

CAUTION DANGER TO LIFE!

And before this is seen as an exaggerated reaction... every year houses collapse in DE and elsewhere where basements are improperly uncovered, regardless of whether the wall is wet or dry!

Haha pickaxe and shovel and off we go!

No no I definitely won't do it alone without experts