Planning a finished basement

Water first

Before anything goes on the walls, find out whether the basement takes on water: stains, a white mineral line on the walls, a musty smell, or puddles after heavy rain. The fix may be outside the house, like gutters and grading that send water away from the foundation, or inside, like a drainage system and a sump. Finishing over a damp basement traps the problem behind new walls.

Mold has its own rules in New York

New York licenses mold assessors and mold remediation contractors through the Department of Labor. If you hire someone to assess and clean up an area of mold larger than 10 square feet, the state says you must use a licensed mold professional, and its mold law says a licensee may not do both the assessment and the remediation on the same property. So the first call is an independent licensed assessor, not the company that would do the cleanup. Revival does not diagnose mold or size the affected area.

Height, light and a way out

• Ceiling height: ducts, beams and pipes often hang lower than the joists. Measure the lowest point, not the average.
• A bedroom needs an emergency escape opening, such as an egress window with a window well. Your building department confirms what your basement needs.
• Heating and cooling: a basement room needs supply and return air, or its own system.
• Moisture-tolerant materials near the floor and on outside walls.

What the space can legally be

A playroom, an office and a gym are simple uses. A bedroom adds the escape opening. An apartment for a relative or a tenant is a zoning question for your town or village, with its own permit and rules, so ask before you design one.

What drives the cost

• Whatever it takes to keep water out, which comes first.
• An egress window, which means cutting the foundation and digging a well.
• A bathroom below the sewer or septic line may need an ejector pump.
• Rerouting ducts or pipes to gain headroom.
• Flooring and wall systems suited to a below-grade space.

Before you sign with anyone

• Check the contractor's county home improvement license yourself: Suffolk or Nassau, plus any town license on the East End.
• Ask for a certificate of insurance sent to you by the insurance agent, not a photo of one.
• Get the contract in writing and signed. New York's home improvement contract law, General Business Law section 771, requires the contractor's license number, a description of the work and materials, the price, the approximate start and completion dates, and a schedule if there are progress payments.
• Know your two protections under that law: you can cancel until midnight of the third business day after you sign, and payments made before the work is finished must be deposited as the state's Lien Law requires, unless the contractor gives you a bond or similar guarantee instead.
• Match each payment to finished work. A payment schedule that runs ahead of the work leaves you carrying the risk.