The Fundamentals of Sanding Wood Floors

Level 1 – Basic Sanding of Oak Floors for a Clear Finish

Writing technical articles for the NWFA magazine for a few years now, I had to take a break for a while. I am back now to writing on a regular basis to share all kinds of information with our beloved contractors.

Taking the trade from the start, I’d like to discuss basic sanding fundamentals. What you’ll read below is a short summary of what needs to be done on a floor to get it ready for a clear finish. That is what most people see; people who don’t understand the craft and the talent that it involves. I will then expand on each point in the next several blogs, and I will detail everything so much that you’ll get sick of how many details there are.

If I said 50 grit..you’d say 40. If I said Trio…you’d say Powerdrive. We all have our preferences of how to sand floors. If I put ten contractors at a discussion table to agree on one sanding sequence for one oak floor, well that could take forever. Reading this blog please understand that I know there are many ways to get somewhere. Your way is probably slower and worse than mine. But really, who cares? Yes, I had to say this to get you out of your reading coma. Laugh, it’s good for you.

Let’s begin:

  • You must cut the floor flat with the big machine. Remember that making the floor flat doesn’t happen when you go with the grain. Woodworkers flatten a piece of wood at an angle using a hand planer or handheld belt sander. You use a big walk behind belt or drum sander. Cut the floor at an angle, then go straight with the direction of the floor.
  • You must cut the floor flat with the edger. That includes all the areas the big machine couldn’t get.
  • Now that the floor is flat, fill it. You don’t have to full trowel it every time. Use common sense.
  • Sand the filler off with the big machine and the edger using a finer grit than your rough cut.
  • Smooth the scratch pattern with a buffer or a multi-disc machine.
  • Take care of the corners with scrapers and sanding paper.
  • Vacuum
  • Tack
  • Seal

Simple, right? Not quite. Sanding and finishing wood floors is art. In the next several blogs I will break down, analyze, and explain each step and what it means down to the very last detail of how you walk your big machine and/or what you think you know about scratch patterns.

Anyway, welcome back Avi to writing again. I’m sure you all missed my stupid humor and unconditional sharing of information.

Be cool.

Avi Hadad is the owner-operator of Avi’s Hardwood Floors in the San Francisco Bay area. He can be reached at avi@avisfloors.com.

10 thoughts

  1. Do you think it is necessary to go on an angle with the big machine if you were finishing off with a trio or power drive?
    Honestly, since we got our trio we stop doing the angle cut and we have saved a lot of time, especially on the larger jobs. Our floors have never been so flat

    1. Hi Chris- the purpose of running the big machine at an angle is to flatten the floor. As long as you’re achieving a flat floor with your system, I wouldn’t change a thing.
      As Avi said, everyone has their own techniques, styles and tool preferences. There really isn’t a “one size fits all” scenario for every floor.
      Brett

  2. Well I finally get to find out your method. Or maybe the method to your madness. I remember you just smiling and nodding and trylng not to roll your eyes when I described to you my process. That’s what I like about you you always had respect for those that came before you even though our methods were quite antiquated compared to today. Even though I always got paid I know my floors weren’t nearly as flat as what you guys were doing today. Welcome back my friend.

  3. I cut the first pass at an angle then the second pass gets cut at the opposite angle. Machines like the Trio are a finish sanding machine primarily, it’s a lot easier to get the floor flat first with the belt sander then just clean it up with the Trio.
    What are your thoughts on filling floors? I’ve stopped filling gaps because I’ve been to too many jobs where the filler is broken out and makes the gap look jagged and ugly. I’d rather see a clean line myself.

    1. That is a great point on the filler. It comes down to the type of wood, the geographical area (which affects movement in the wood) and the type of filler…Also we have a lot of top nail floors here in California so that is a whole different animal. I promise to expand on the topic in the future posts. Thanks for the comment Joshua!

  4. we refinished an oak 3/4″ floor. machine caused severe wave/chatter. we’ve since sanded twice more but can still see a bit of wave. Homeowner says I owe her a new floor and I’m telling her there is a lot of life in her floor. I’m trying to get ideas on how many times a solid oak floor can be sanded. Any comments?

    1. That is a tough question because everyone sands differently and removes a different amount of wood when sanding is complete. Just for reference take a new 3/4″ solid oak floor. I’d say a good 5-6 times of sanding, PROPER sanding and I don’t mean start with 36 grit. That is ideal but we don’t live in a perfect floor world, do we? Wave and chatter are two different things and I am sorry to hear you are having trouble on this job. Try to reach out to a local Nwfa certified member or someone with a Trio or a multi disc machine. Even if your belt sander leaves chatter the Trio will take it out.

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