I don’t plan to add a bathroom or bedroom but there’s moisture so I guess it’ll need to be waterproofed.
$25 per Sq ft to finish a basement. Includes labor and materials, floor, ceiling, lights ,painting, trim and doors. Which is $20,000 Waterproofing 800 Sq ft is 9 per foot. Which is $7200
The average homeowner spends around $4,017 to seal a basement or foundation, with minor repairs costing as little as $600. More comprehensive issues that include fixing cracks in the foundation or adding drains & gutters can cost upwards of $10,000.
A basement drainage issue is one of those scenarios where to properly address the problem can only be done by an assessment to determine where water is coming from.
There are those who attempt to solve the problem with partial fixes including shallow curtain drains or even cutting a grove in the concrete basement slab INSIDE the walls and allowing the water to flow toward a sump pump.
In our humble opinion both “solutions” are inadequate as the water will still find its way into the home and be a source of moisture and/or mold.
In our opinion the only thorough and permanent solution is to install a full depth curtain drain to BELOW the basement footings and make certain any uphill surface and/or ground water is directed around the home.
The waterproofing solution depends upon your exact conditions as REI Contractors indicated. Two of our most recent groundwater mitigation bids for projects in Seattle were around $12,000 for an exterior collection drain (including excavation and backfill), fluid applied waterproof membrane on the exterior of the basement wall, drainage mat, and connection to the side sewer.
The cost of finishing the basement depends on the configuration and material selections. For an open room (no interior partitions) this could be as little as $25/sf. For addition of rooms it could go up to over $100/sf (new wiring, heating system adjustments, framing, etc).
There are so many variables that make up the pricing. Waterproofing prices will vary depending on the type of foundation you have as well as what exactly your specific basement would need. For example, waterproofing consists of repairing leaking wall cracks in poured foundations as well as repointing stone foundations, both prices are very different. If you have a high water-table you may need a sump pump, or your bulkhead may need additional waterproofing.
Building plans need to be completed to estimate this.