How To Refinish Hardwood Floors: Part One

How To Refinish Hardwood Floors: Part One

Trent Johnson
Feb 3, 2010

I refinished my hardwood floors two years ago, and I'll be honest: it's HARD work. But if you have the time, patience and energy, you can do it. It'll probably save you money and allow you to opt for greener finishing options. There are two options when it comes to floors: a complete refinish, which requires sanding down to bare wood (Part One) and screening, a process that only takes off the top coat of polyurethane (Part Two).

Most hardwood floors are made of oak, which is what I have experience doing myself. They are often sealed with a polyurethane finish.

To revitalize old floors, there are two options:

  1. A complete refinish which requires sanding down to bare wood. This is best for floors that are very well worn with stains, water damage or deep scratches.
  2. Screening, a process that only takes off the top layer of polyurethane. Screening is good for floors on which the finish is warn, scratched or dull but the wood below is not damaged (by water, deep scratches or stained).

This how-to will cover the first option, sanding down to bare wood. Next week we'll tackle screening, a much easier and less intensive option. Why is this green? Rejuvenating an old floor to make it last longer is always a great option than replacing it or covering it up. You can also use a water-based polyurethane and low VOC stains.

Equipment and Tools

  • Painters Tape
  • Plastic
  • Fan
  • Tack cloth or damp towels
  • Hammer
  • Wood Putty
  • Putty Knife
  • Drum Sander (rent)
  • Large palm sander (rent)
  • Sanding discs for each above sanders
  • Low VOC stain!
  • Polyurethane
  • Old cotton rags (for applying stain)
  • Paint brush (for applying Polyurethane)
  • Old socks
  • Extension Cord
  • Respirator or good dust mask
  • Old clothes or disposable coveralls


1. The Preparation:

  • Remove everything from the room including wall hangings, and curtains.
  • Seal all doorways with plastic sheeting and tape.
  • Place a fan in a window to blow dust out and bring fresh air in through another window. Make sure to wear a respirator and clothes that you don't much care about.
  • You'll probably want to remove your baseboards and use painters tape around door trim, etc.

2. Fill Any Holes:

Ensure you have a uniform surface. Fill any small gaps or holes with wood putty and a putty knife. Any larger gaps you'll want to fill with a small piece of similar wood, and the edges with putty. Tap into place and glue any filler wood. Also check for any nail heads that could puncture your sandpaper. Remove or pound in with a nail set.

3. Sanding:

The rental center will rent you a drum sander for about $60 per day. They also sell you the sanding discs needed for the drum sander and tell you how to use the equipment. Begin with a heavier grit paper (60 grit) and never stop the machine while it's engaged! Do the entire room at one grit and then switch to a lighter grit, until it's nice, smooth, and uniform and all the polyurethane and stain has been removed. Advice: begin rolling the machine forward as you engage the drum and be sure to disengage before you've stopped moving forward. It takes a while to learn how to use it efficiently. Practice in one of the back rooms before moving into the main living space just in case. Stay away from any door trim (you'll get this later with a palm sander). Make sure you move at a steady, even pace and let the machine do the work. Keep the machine in a straight line while engaged and always disengage before turning off the machine. Dispose of the sawdust outside as it can be very flammable. Also, make sure to wear a quality dust mask.

4. Sanding the Edges:

Using a palm sander or a heavy duty edger (available to rent at home improvement stores), finish the edges so they match the center of the room. Again, BE PATIENT and keep the sander level no matter how much you want to apply pressure to get it done faster. It is well worth being patient as to not dig into your floor. Use a similar grit progression as you did with the drum sander. Get as close to the door trim as possible but don't nick it or it will leave marks. This is a painstaking and back testing job.

5. Clean up the Dust:

Once you have the floor stripped of previous finish, it's time to get rid of all the dust. First, sweep up as much as you can. Then, vacuum everything. Next, use a damp cloth or tack cloth to wipe down every surface: Walls, window sills, floor, anywhere dust might be hiding.

6. Staining the Floor:

Next is the fun part. Choose a stain for your floor. We picked a Minwax VOC Compliant Red Oak and applied using old cotton shirts. One person applied the stain with the grain in liberal amounts, and the other came behind to wipe off about 10 minutes later with a clean piece of cotton. Make sure to use socks you don't care about as they will be ruined! Let dry for at least 24 hours depending on humidity. Be sure to follow all of the directions on the bottle for best results, and keep the room well vented during application (it will also speed up drying).

7. Protective Finish:

For the finish, we used a water based Polyurethane from Minwax (Water Based Polyurethane for Floors). The advantages of a water based finish over that of oil-based is a quicker dry time (you can begin the second coat sooner) and less noxious fumes. On the downside, oil-based polyurethane can be worked when wet (to correct mistakes - and supposedly better for beginners) unlike water-based, and is said to perform better in high traffic areas. For our 1,000 sq. foot house, we went through about 5 gallons of the stuff for three coats.

Begin in the corner of the room because you won't want to walk on this stuff (unlike the stain). Again, wear socks you don't care about. We used large bristle brushes to apply moderately, with the grain. Be sure to avoid any bubbles while applying. It's relatively self leveling so all you do is apply, and let dry. Do keep the room vented while applying to avoid fumes. Because it was rainy outside and rather humid, it took our floors a solid 24 hours to dry between coats. Following the manufacturer directions, we didn't sand between the first two coats but did lightly, using 400 grit paper, between the 2nd and 3rd.

Be sure to let dry thoroughly before the final coat, and then enjoy!

Additional Notes:

Refinishing a floor is a tough project. Above are the steps that I followed to a successful refinishing job, but there are different ways to tackle this project. It took me and my (now) wife two weeks between preparation, sanding and finishing (working only at night and on weekends). During that time, we still had our previous residence. I'd recommend consulting with a professional and weighing the costs associated with doing it yourself and hiring a professional.

See also ThisOldHouse: Refinishing School

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