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Refinishing Wood Floors

Our old wood floors are absolutely packed with character. Here is our three step process for refinishing wood floors.

After months and months of working on the kitchen, of rebuilding pantries, of hanging beadboard, of plotting designs, it is finally time.

Time for refinishing wood floors. This is one of my FAVORITE parts of the whole project and makes us feel like we are finally getting somewhere.

Our house’s floors are Douglas Fir, which was a common flooring and sub-flooring material at the turn of the century. They turn a gorgeous, rich orange color when refinished that is just POSITIVELY SCRUMPTIOUS.

Without further ado, let’s get to refinishing wood floors.

Step 1: Prep for Refinishing Wood Floors

Before you go rent any equipment or pick out stain colors, make sure you prep your floors really well. Prepping generally involves three things.

Fix Damaged Areas

Any areas where the supports underneath have rotted out or water has damaged the floorboards needs to be repaired first.

For our floors this involved completely rebuilding several sections including where the old (massive, hideous) fireplace was, where previous owners cut in to the floor to add ducting, and water damage under the sink.

Sink Nails

The number one destroyer of sanding pads is unknown nails. Before you start refinishing wood floors, carefully examine every single board for nails sticking up.

Use a nail set and a hammer to drive the nails down below the level of the surface.

Block Off the Room

Most rental sanders are supposed to be dust collecting. But…dust still goes LITERALLY everywhere. We seal off doorways with vapor barrier and painter’s tape.

Even if the room has a door on it, tape all the way around the door and over the keyhole. Renovation is messy enough. Don’t let refinishing wood floors in one room make your whole house a disaster.

Step 2: Sanding

Hey!!! The fun part! Well it’s fun for 0.2 seconds, then it gets a bit less fun.

Tools

We rent two different machines when we sand our wood floors. First we rent an edge sander – a little tank weighs a million pounds. But it’s great for getting right along the edge of each room.

Second we rent a drum sander. This machine is heavy, powerful, and very loud. But it does a great job leveling out the majority of the room.

Tip: Our local rental place is closed on Sunday. So we pick up our machines on Saturday and return them Monday for the price of a one day rental. See if your local rental place does the same!

Last we use our own personal palm sanders. These aren’t strictly necessary and professionals probably don’t use them. But we don’t try to get all the warped-ness out of our floors. So these come in handy to finish up the last of the job (more on that in a minute).

Sandpaper

Our local rental place sells sandpaper right along with the rentals. This is super helpful because it guarantees we don’t buy the wrong materials.

Sandpaper comes in different grits. The lower the number, the rougher the sandpaper, and the more material it will take off. In our experience, you want to buy a lot more low-grit sandpaper than high grit.

We usually start at 20 grit to power through the dirt and paint on most of the floors. More often than not, we tear these sanding strips several times. So it’s always good to have extra.

Tip: Save your old sanding pads after you refinishing wood floors! Use them as the first pass next time to check for nails. Better to rip used pads than new ones.

Our full sequence is 20-36-60-100-120, but only the first four grits use the rental machines. Last we use 60 and 120 grit with our palm sanders.

Technique

You can watch a lot of videos on different techniques to actually use the tools you have. But there is one general rule: don’t stop moving.

When using the drum sander, you want be moving before you set it down against the floor and lift it up before you stop moving. When sanders aren’t moving, they’re eating in to the wood.

We start at one side of the room in the middle and follow the direction of the wood as we move to the other. Each pass will take off a little more material.

We aim to get the floors about 80% smooth with the 20 grit. This may take anywhere from 4 to 20 passes if the floors are really bad.

Once we’re happy, we drop to 36 grit. Then after it’s about 90% smooth, we typically do two passes each of 60 and 100 grit.

At this point, we go to work with palm sanders on any areas that we didn’t get well enough with the larger tools.

The finished floors are beautiful and smooth, but not completely flat. They reflect their age.

A Note About Cupping

Cupping occurs when the boards bow upward a little due to moisture and humidity changes. This is totally normal for wood, but in a 115 year old house, some of our floors are SERIOUSLY CUPPED.

One technique is to pass the drum sander at a forty-five degree angle to try to eat through some of the cupped sections. This personally scares the life out of me.

We choose to smooth as much as we can with the heavy duty tools, and detail sand any really cupped boards individually.

Finally after all that work, it’s miracle time. We can at long last add the finish coat. But…I absolutely must point something out first.

Please follow me into a tiny detour into materials science. It’ll be fun, I promise.

What is hardness?

If we can get through this entire section without absolutely devolving in to middle school humor it will be a miracle, but we must discuss wood hardness for roughly two seconds. GO ON. GIGGLE.

Hardness is actually a weird material property to measure because you can only specify something’s hardness when you compare it to something else.

There are many different scales of measuring hardness. Different scales are more suited for different types of materials. The Rockwell Hardness Scale and Brinell Hardness Scale are two scales I learned about in college (and subsequently the last time I used my Materials Science degree, until now).

Wood is measured in the Janka Scale. The test pushes a small ball in to a sample of wood with a certain amount of force, then you measure the indent. Harder materials indent less, softer materials indent more. Cool, right?

“PAIGE. WHY ARE YOU TELLING US THIS.”

Ok ok ok there is a point to this I promise. Many people these days use the term “hardwood flooring” to simply mean any wood floors. But there is actually a cut off on the Janka Scale the separates hard wood and soft wood.

If you sift through this wikipedia page AND remember that we have Douglas Fir flooring in our house, you’ll see that we don’t actually have hardwood floors. We have soft wood floors.

Oak floors have hardnesses of between 1100 and 1400 pounds force. Our Douglas fir floors have a hardness of 660 pounds force. That’s less than half!!

What this means? Our floors damage easily! More easily than a lot of common flooring materials. So when we are refinishing wood floors in this house, we want to take extra precautions to help protect the finished surface.

END OF MATERIAL SCIENCE RAMBLINGS

Step 3: Refinishing Wood Floors

There are many different materials you can use to refinish your wood floors including waxes, oils, water based, and oil based polyurethane.

But considering our softer-than-normal flooring, we chose Pro-Finisher Low VOC Oil Based Polyurethane. The first coat seems to soak in to the wood and actually harden it up a bit, which I LOVE. So that’s what we went with.

Satin seems to be a more modern sheen, but I absolutely live for shiny floors, so we use semi-gloss.

Clean Up

The key to getting a good final result is to make sure you clean clean clean before you poly.

Vacuum every single solitary surface in the entire room. Walls. Floors. Ceiling. Floors again. Light fixtures. Trim. Windows. Floors. EVERYTHING. You do not want dust falling in your finish coat.

I even let the room sit overnight, then vacuum again to make sure I get as much up as possible.

Wipe Down

To get the very last bit of dust off the floors, I wipe down the entire surface with odorless mineral spirits.

Do not use water. Water takes forever to dry and can raise the wood grain, thus undoing all the hard work you’ve already done!

I use gloves, a rag, and a small bucket to wipe off each and every board. Let that dry for a few hours.

The mineral spirits will actually show you what color the floors will end up, so that’s always a fun moment.

Applying the Polyurethane

I have tried this two ways. For the first two rooms I used a lambskin applicator on an extension pole. While this did lay down a nice coat of poly, it was messy and made it very hard to see if I had puddles.

This time I used a large four inch paint brush to smooth on the poly, and it was MUCH nicer. I start in the corner farthest away from my exit point.

Methodically paint down the boards working your way across the room, making sure to get every spot.

Re-coating with Polyurethane

Let the polyurethane dry for 1-2 days. Then sand the whole floor lightly with 220 grit just to knock down any high spots. Wipe up sanding dust with a rag and water (do NOT use mineral spirits after the poly is down. It will destroy it).

Once your coat is sanded and wiped up, you can apply a second coat of polyurethane. Usually we apply 3 coats per room, but you could apply more.

Theoretically if the poly ever starts to look bad, we could do this same technique of light sanding and repainting. That’s a win in my book.

Tips for Refinishing Wood Floors

Give yourself some grace: I’m not a professional floor refinisher. And you probably aren’t either. DIY is all about learning, making mistakes, and getting better. Your first floor won’t be perfect. Your second won’t be either. It’s ok. Keep going.

Don’t skip grits: Skipping grits doesn’t make the work faster. Rough grits make big gouges in the floor. In order to smooth those out, you have to use smoother grits. But if you skip from 36 to 100, it is like trying to flatten a mountain with a shovel – not enough oomph to get the job done.

You will scratch it: Every person who has refinished floors has confessed they’re worried about scratching them. It’s going to happen. Stay out of the room long enough to let it dry, but then get on with living in your own house!

That’s more or less our whole process for refinishing wood floors. It takes some practice, but you can absolutely do it yourself! Questions? Leave them below!

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