How To: Refinish Hardwood Floors

How to Refinish Hardwood Floors - After

Photo: Joe Provey

Floor sanding and refinishing is unforgiving work. Make a mistake and it will show. However, a refinished floor can bring beauty to a room like no other project. To hire a pro to sand, seal, stain, and apply several finish coats of an oil-based poly will cost $4 per square foot, or more. Doing it yourself can save at least half of that. Think you’re up for it? Here are some helpful tips:

1. Choose DIY-friendly sanding equipment
Unless you plan to sand many floors in your lifetime, random orbital sanders are the best choice for do-it-yourself floor refinishers. They take longer to remove old finishes than drum sanders, but they do not require a lot of experience to use and are less likely to damage your floor. With a random orbital sander, you can move with or against the wood grain. Just be sure to keep the sander level at all times. Even an orbital sander can “run away” from you and cause sander markings that are difficult to remove. To learn more about random orbital sanders, click here.

Related: Kitchen Flooring: 8 Popular Choices

2. Watch your back
Avoid back injury when transporting sanders from the rental store to your house (or up stairs) by always having a helper. Use ramps to move the machine whenever possible. Similarly, get help moving heavy furniture out of the room. (It has to be completely emptied before you begin.)

How to Refinish Hardwood Floors - Sander3. Take precautions
Floor sanding and refinishing generate a large amount of dust and fumes. Stock up on dust masks and earplugs and, when applying sealers and oil-based polyurethane, wear NIOSH-approved organic vapor respirators, neoprene or vinyl gloves, and eye protection with splashguards.

4. Don’t get too aggressive
Begin with coarse-grit abrasives sufficient to remove the old finish and most surface scratches. Avoid using grits coarser than 60; this will help keep you from damaging the flooring. Proceed with abrasives that are gradually finer until you reach the desired degree of smoothness. (My preferred progression for a hardwood floor such as oak begins with 60-grit abrasive, goes to 80-grit, and finishes with 100- or 120-grit.) Sand as though you are mowing the lawn. Proceed row by row, overlapping runs by half the sander’s width. You will have to make numerous passes with each grit.

5. Remember the corners
A palm sander may be used to sand near baseboard moldings, but use a sharp scraper to remove any areas of old finish the sander may miss. Scrapers allow you to get into recesses (along board edges, at butt joints) without having to remove a lot of material with the sander.

6. Guard against dust and hair
When you’ve finished sanding, remove all dust by vacuuming and wiping the sanded areas with tack cloth. If you find a stray hair embedded in dried polyurethane and you still have at least one coat to go, lightly sand over the hair with a very fine (320) abrasive. Carefully dig out the hair with a pin or fingernail, if possible. Then resand with the same very fine abrasive, taking care not to breach the stain layer. Upon recoating with poly, the hair mark will all but disappear.

7. Sealing the deal
A sealer coat is not normally needed, but if your floor takes stain unevenly, it will help ensure even stain coverage. Test for this by applying stain to an area that will not be visible once furniture is moved back into place. It is important to apply the sealer evenly. Otherwise, ‘holidays’ (skipped areas), stop marks, and lap marks may show through after staining.

How to Refinish Hardwood Floors - Stain

Photo: Joe Provey

8. Apply stain evenly
Applying stain evenly, especially over a large expanse, isn’t as easy as it might seem. I find that the best technique involves applying the stain with an applicator to one small area at a time (about 18″ x 3′) and then rubbing off all excess with a rag. Avoid letting the leading edge of your job dry; you will end up with lap marks (stripes). Oil-based stains stay workable longer than water-based.

9. Thin coats are better than thick
Many pros pour polyurethane along the floor and then spread it with an 18-inch lamb’s wool applicator, but for the novice this is likely to result in a layer that’s too thick. A better way for the do-it-yourselfer is to roll on the polyurethane using a foam roller, preferably a high-density foam roller. The coat will be thin, even, and will quickly dry to a glassy smooth finish. Use a good brush for cutting in around the room perimeter.

How to Refinish Hardwood Floors - Polyurethane

Photo: Joe Provey

10. Have an exit strategy
Begin your applications along the wall opposite the door you intend to exit. Work in parallel rows toward the wall with the door. When you get close, you will have to change your work pattern and work from the end walls toward the door. This makes it tough to achieve uninterrupted smoothing strokes, so apply a little extra poly and count on its self-leveling properties for a smooth finish.

For more on flooring, consider:
Wood Flooring 101
The Beauty of Reclaimed Lumber
Installing Hard Maple Flooring