Also - get commentary / bids from multiple contractors before you do anything, and do a lot of research to try to determine the true problem.
A cautionary tale regarding wet-basement remediation:
6 years ago, we put our house on the market. A few years before, we’d found some water in one corner of the basement; determined it was probably because of a nearby downspout; fixed the downspout, and we didn’t notice any additional wetness so we thought the problem was fixed.
A week after getting a contract to sell our house (a townhouse)… yep, we found the carpet wet. We got 4 different basement-wetness-remediation contractors and got 2 different sets of answers. Two said it was water seeping in from the outside at ground-level; they recommended removing the existing few inches of soil, replacing it with something with a higher clay content, and grading it so it sloped away from the house. Anything more than that was a waste of money. This would cost us 600+ dollars.
The other two recommended digging a french drain around the front perimeter of the house, inside (i.e. blasting through the concrete), laying a bed of gravel and perforated pipes, and pouring into the existing sump pump. The problem was clearly because of groundwater seeping up, not surface water seeping down. Anything else other than that was a complete waste of money. This would cost several thousand dollars.
Well, the buyers were considering going through with the purchase anyway (we of course disclosed this problem to them as soon as we found the wetness and got the bids), with the understanding that we would fund whichever solution wound up being the answer. Then shortly before closing they did some poking and found water still seeping in, even though there hadn’t been rain in a week or more at that point.
They were literally minutes away from walking away from the contract to purchase (and, as we’d already put a contract on a new house, this would have been scary). I mean, within 5 minutes; their realtor had already left and they were about to walk out the front door.
When the next door neighbor’s brother - who had been staying at his brother’s place for a few days - knocked on the door and said he thought he knew the cause of the problem.
The inside component of the air-conditioners had an outlet pipe to drain water condensed from the air. That pipe was not fed directly into any sort of drainage system, instead, it was laid on the floor, fed to a drain in the floor of the furnace room.
That pipe had been knocked away from the drain.
The water was not going down the drain… it was seeping across the floor of their furnace room, to the wall between our units, and into our basement. The neighbor’s brother had spotted this the night before, fixed the pipe, and just happened to find us at home that day (it was midday) and tell us the problem.
So - a frantic phone call to the buyer’s realtor to get him back, and a troop of about 8 people trekked down to the neighbor’s basement, and then back to ours to confirm that at present, our basement was bone dry.
We had to spend about 5 hundred dollars doing drywall repair and recarpeting the room, and the sale went through. The buyer also asked that we do the soil replacement / regrading. Which, to make the sale go through, we were quite happy to do.
So the moral of the story? 4 different contractors, all with different answers… and ALL WRONG! NOTHING any of them suggested would have fixed the problem.