Prep the Subfloor
The most important step most people skip. A level, clean subfloor is the foundation of every good flooring job. Skipping this causes squeaks, gaps, and premature wear.
Time Required
4-8 hours
Cost
$50-$300
Difficulty
Moderate
Subfloor Prep Steps
Remove old flooring completely
Pull up carpet, pad, and tack strips. Remove laminate or vinyl and all adhesive residue. Pry up damaged baseboards carefully if you plan to reuse them.
Check for level
Place a 6-foot level or straight board across the floor. Variations greater than 3/16" over 10 feet need leveling. Mark high and low spots with chalk.
Level the subfloor
Fill low spots with self-leveling compound. Sand down high spots with a belt sander. For plywood subfloors, secure loose sheets with screws to eliminate squeaks.
Install underlayment
Floating floors need underlayment for sound dampening and moisture protection. Roll it out with seams taped — overlap edges 6 inches and seal with the manufacturer's tape.
Common Subfloor Issues
- Squeaky spots: Drive screws through the subfloor into joists. Use a stud finder to locate joists.
- Moisture: Test with a moisture meter — wood subfloors should read below 12%. Concrete should be below 3 lbs per 1,000 sq ft.
- Rot or soft spots: Cut out damaged sections and sister new plywood. Don't install new flooring over compromised subfloor.
- Adhesive residue: Scrape with a floor scraper and use adhesive remover. Remaining lumps will telegraph through new flooring.
Pro Tips
- •Rent a floor scraper: For large rooms, renting a stand-up floor scraper ($40-$60/day) saves hours compared to hands-and-knees work.
- •Don't skip the moisture test: Moisture under new flooring causes warping, mold, and voided warranties. Spend 10 minutes testing before you install.
- •Acclimate your flooring: Leave new flooring material in the room for 48-72 hours before installing so it adjusts to humidity and temperature.