Wood Subfloors

• 1). Walk all areas of the subfloor as you listen for squeaks that indicate loose nails or screws. Circle any areas that squeak with a carpenter’s pencil or lumber crayon. Drive any loose or raised nails with a hammer.
  
  
• 2). Set up a power or cordless drill with a screw-tip attachment. Drive 2-inch wood screws next to the existing nails or screws within each of the circled areas.
  
  
• 3). Walk the subfloor a second time, to ensure all loose sections have been eliminated. Drive additional 2-inch screws, as necessary.
  
  

Leveling Wood and Concrete

• 1). Select a piece of 2-by-4-inch lumber that has straight edges instead of bowed or dipped ones. Cut a 6-foot-long piece with a circular saw or handsaw as a straight edge.
  
  
• 2). Place the straight edge on edge atop the subfloor and parallel with one wall. Move the straight edge across the floor in 12-inch increments, as you sight along the lower edge and look for gaps indicating low spots in the subfloor. Circle any low spots as you go. Repeat this step until you have located and marked all low spots in the subfloor.
  
  
• 3). Mix a batch of acrylic-based floor leveling compound to medium consistency, in a 5-gallon bucket with a 2-inch plastic putty knife.
  
  
• 4). Ladle a modest amount of the leveling compound within a circled low spot, with the putty knife. Smooth the compound to conform with the adjacent areas of the subfloor, using an 18-inch steel trowel. Use moderate pressure on the trowel instead of pushing hard, which creates dips.
  
  
• 5). Repeat the previous step, and level the remaining low spots. Allow the compound to dry overnight before you begin installing the hardwood.