Why do I have to sand my brand-new, raw wood floor?

by | Sep 6, 2022 | Sand wood floors, Sanding floors, Wood floor advice

It’s new; isn’t it already perfect?

I know – this seems crazy, right? This beautiful, fresh-from-the-mill, newly-planed wood gets nailed to your subfloor, and now you have to sand it? Why??

It’s not that the wood surface isn’t smooth.

After installation to your never-quite-perfect subfloor, the edges of your new floor boards will all be at slightly different heights. If you run your hand across the boards you will fell some “lippage” where some edges are just slightly higher than the adjacent boards.

It seems minor, but there are several reasons you can’t just leave it as is:
  • You will be able to feel this if you walk across the floor in bare feet
  • It becomes a splinter risk over time
  • Low spots allow stain to pool, leaving areas of darker or more intense color
  • High boards and edges also wear faster than lower spots, leaving some areas exposed to bare wood mere months after refinishing.

So most floors are sanded just enough to bring every board edge to level with the board next to it. Yes, this does put new scratches into the faces of these beautifully planed boards.

Let it go.

You will use carefully chosen, progressive grits to remove the scratch damage you needed to make it level. And you will do your best to to not leave any evidence of the whole process.

 

But what grits do you use?

For new white oak floor sanded with a typical rental-agency drum sander and edger, a common sandpaper sequence is

  1. 60-grit drum
  2. 60-grit edger
  3. 80-grit drum
  4. 80-grit edger
  5. 100-grit screen on a flooring buffer to blend drum and edger zones

BUT, if you choose to rent a multi-head random orbital sander (or example a U-Sand) instead of the drum and edger combination you will need to start sanding at 36-grit instead of 60, and it will take longer.

But for new maple…

Maple is a harder wood that will take more work to make level. You will most likely need:

  1. 36-grit drum
  2. 60-grit drum
  3. 60-grit edger
  4. 80-grit drum
  5. 100-grit edger, then 100-grit screen on a buffer

Notice that we did not suggest 36 for the edger in this case; usually edgers are so aggressive that they can level lippage with a 60-grit even on maple. Even if it takes a bit more work, we think it is better than putting in all that 36-grit edger swirl, which can be challenging to remove once it is in.

If you are using a multi-head random orbital to sand maple, it is likely you will need to start at 24-grit and work your way back up to 100-grit to ensure than all the sanding marks are gone.

Note: sanding professionals are going to rage and rail in the comments about these suggestions, but they have access to more and bigger machines than most homeowner DIYers. These are guidelines for the type of equipment most non-professionals can access and operate.

 

Yes, there are some exceptions.

There are many mills selling wood with deliberately preserved saw-kerfs and mill marks. Obviously if we sand these products aggressively, many of those beautiful character marks would disappear. So, manufacturers of those floors usually advise use of a square-buff sander or a rotary flooring buffer, just to remove any minor flaw from shipping or installation.

Unfinished beveled-edge floors are usually not designed to be aggressively sanded after installation because the micro height differences between boards are in effect hidden by the tiny groove that forms where the bevels meet between boards.

These floors are usually just screened with a rotary flooring buffer at 100- or 120-grit to remove marks from transit or that spot where you dropped your hammer while you were installing.