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Fix Cupped and Damaged Hardwood Floors


Tuesday we talked about the nightmare that is cupping in a hardwood floor. Cupping is a type of warping that occurs in hardwood flooring when exposed to too much moisture. This could come from spills, leaks, humidity or sub floor damage.

While you can reverse some of the effects of cupping by drying the damaged boards and regulating the humidity in the room, the only way to really rid your floor of cupping, aside from replacing it, is to sand it down and refinish it. Luckily, we have some advice on how to go about the process!

1) Figure Out Your Floor

For the floorboards that are nice and flat you will want to sand with the grain of the wood, but for areas that show cupping or other forms of warping you'll have to sand sideways against the grain. Sand over the floor twice - right to left, then left to right - before going over it a final time. On the last round, go with the grain.

Note: You will need to change your sandpaper with each round over the floor, switching it out for a lighter grain each time.

2) Get Your Supplies

Floor sanding can be a messy process; dangerous if you don't have the right gear to protect yourself from fine dust and debris. You'll need:

  • Eye protection

  • Ear protection

  • A face mask

  • A long shirt and pants

  • Door masks or covers to keep the mess contained

  • Open windows for ventilation

You will also need to rent/purchase three separate sanders in order to get the job done, along with shape-specific sandpaper for each one.

  • Heavy-duty drum sander

  • Heavy-duty edging sander

  • Corner Sander

Note: Follow the directions for each sander carefully for safe use.

3) Get Your Floor Ready For The Big Day

If you're bringing a sander into the picture, you'll have to prep your floor. Neglecting to do so could result in damaged sanders or floor boards.

First, grab a hammer and nail down any loose floorboards. The nailhead should end up below the surface of the floor. Once that's done you can do one more sweep of the room to verify that there are no protruding nails or screws to contend with. This is extremely important because you could end up damaging the sanders, hurting yourself, or ruining the sandpaper. If you're confident that all is clear you have the green light to begin.

4) Time For A Drum Solo

The first sander you'll want to reach for is the drum sander. This particular machine will give the power to sand the largest area of your floor. Start by preparing your drum sander according to the directions it comes with, making sure that when you load the sandpaper it remains taut. Above all, keep the sander unplugged until everything is in place and ready to go.

From there, you can begin your work. Tilt the sander upward and turn it on, then carefully lower the sander to your floor. To do the job effectively, start in the corner of your room and sand at a diagonal. After the first round change directions and sand parallel to the wall. Take your time with this machine, so as not to damage your floors with it.

5) Grab Your Edging Sander

When you're done with the vast majority of the floor you can begin to pay attention to the finer details. Prepare the edging sander for use, then sand along the outer edges of the room, careful not to hit the wall.

6) Conquer The Corners

The Name is probably enough for you to guess, but you will use the corner sander to finish sanding those hard-to-reach areas on your floor. Go about this carefully. Precision is the goal for your edges, so you don't want to make hasty movements that could lead to mistakes.

7) Clean Up

While it may not be the most fun for every individual, this is certainly one of the most satisfying parts of the sanding process. Sweep AND vacuum the floor, then go over the entire area with a LIGHTLY damp sponge. You need to be thorough about removing the leftover dust from the sanding bags because the look and feel will suffer after the final step is completed otherwise.

8) Finish Up

Complete your project by applying your favorite finish or varnish.

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