Trace plumbing lines and note locations of shutoff valves can supply lines: which are natural points for adding new pipes :r redirecting old pipes. If you ere considering a bathroom or kitchen addition, also trace drain lines back to the main drain stack, and take measurements to determine if adding new drain lines is feasible.
Evaluate headroom in your basement, paying particular attention to ductwork that is mounted below the bottoms of the floor joists. In many cases, you can reroute the ductwork so it runs in the joist cavity.
Look for asbestos insulation, usually found on hot air supply ducts from the furnace. Asbestos removal is dangerous and closely regulated, but it in many cases you can do it yourself if you follow the right proscriptions. Check with your local building department or waste management authority for more information on asbestos abatement in your area.
Identify sources of standing water and visible leaks. If water comes into the basement on a regular basis through the foundation walls or floor, you’ll definitely need to correct the problem before you begin your basement project.
Inspect foundation wall cracks to see if they are stable. Draw marks across the crack and take measurements at the marks. Compare measurements for a few months to see if the crack is widening. If the crack is stable you can repair it (see page 30). If it is moving, contact a structural engineer and resolve the problem before you begin your remodeling project.
Probe small cracks in poured concrete walls and floors with a cold chisel to evaluate the condition of the concrete. If the concrete flakes off easily, keep probing until you get to solid concrete. If the crack and loose material extend more than 1* or so into the wall, contact a structural engineer.
Check the mortar joints on concrete block foundation walls. Some degradation is normal, but if gaps wider than 1/4* have formed, you should have the wall repaired before you begin building.
Check for bowing in basement walls, water pressure in the ground often causes concrete walls to bow inward over time. As long as the amount of bowing is less than 1 or 2″ and the bowing is not active, you can usually address the problem by furring out from the wall with a framed wall.