We are trying to figure out next steps in waterproofing our semi-finished basement and hoping to get some advice from the knowledgeable folks on this board.

We live in a semi-attached house in Brooklyn, NY that we bought a few months back. We would like to finish our basement that currently has concrete floors and brick walls covered with sheetrock in several places. The basement is half (6 ft) below ground and there’s some signs of water damage on the portion of the walls below ground, a moisture reader goes crazy when used on those walls and it has a musty smell. There are no actual leaks except for some water towards the front corner we saw once during a rain storm (it has rained hard a bunch of times since, but the leak was there just the one time).

We’ve had a number of contracts come to take a look and have gotten conflicting recommendations.

• Several suggested full external water proofing (breaking cement outside, digging to the foundation, etc). And they mentioned that there was no need for pipes/gravel below the surface to route water away from the house since our area has a low water table.
• One mentioned that there are 1 inch gaps between the cement blocks on the ground outside the house and filling in those gaps should be enough.
• A couple suggested that we should do internal French drains.
• Another mentioned painting the outside and sealing the very tiny cracks we have on the cement/exterior.
  Based on the info provided is there any way to tell what the right way forward is here? Our concern is doing more harm than good with something as major as digging up the foundation to perform external water proofing. We don't mind taking the more conservative approach first, if it has a realistic chance of working.
  
  Thank you in advance for the advice!

 

Your asking questions for what appears to be a unique building that sounds much different from the normal application we come across here,

Some pictures would be greatly appreciated, but in general you seem to have been provided a wide range of options, I would certainly consider starting with the simple ones first!

 

Welcome to the forums!

Waterproofing is always best achieved from the exterior side although that is also often the most expensive option. An interior drain is basically water mitigation to remove what water comes thru the foundation and normally relies on a pump to remove that water.

You definitely want to fill any gaps in the foundation wall! That and priming the exterior walls with drylok with an exterior latex top coat - or any primer and an elastomeric top coat will help. If it will be enough depends on how deep the leaks go.

Don't forget about piping downspouts away from the house and fixing the grade if water runs toward the house.

 

Thanks to those that have already replied.

We're leaning toward exterior waterproofing. As we have a lower water table, do we need anything to divert water away from the house (drain through a pipe, etc)?

i've attached some pictures of the outside and basement, in case they are helpful.

Thanks!