10/11/2026
Plan on $90,000 to $150,000 for a finished lower level with a full bathroom in Central Maryland. Larger spaces, higher-priced finishes, or plumbing and moisture repairs can cost more.
A full bathroom adds plumbing, fixtures, waterproofing and tile work. A new drain below the floor may require cutting the concrete slab and trenching, which can add time.
Low ducts and beams also affect the plan. We plan around them before framing, and where practical we move ducts to limit boxed-in sections of ceiling. Size, finishes, moisture and existing plumbing also affect the price.
Three tiers: open finish, finish with a bath, finish with a bedroom and a bath.
The images are design renderings.
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