Q: We have manufactured hardwood floors, and the previous owners did a shoddy job of refinishing them by slapping down polyurethane on top of the original coating of the manufactured wood.
The polyurethane is flaking excessively and I can’t take it any longer. What steps do I need to take to rectify this manufactured floor refinishing situation? My husband and I are great at renovation and projects, more than comfortable with whatever we need to do, just want to make sure we know the correct steps to take.
A: It is not a surprise the finish is flaking off. It is a guaranteed outcome. Factory finished floors use finishes that by design are abrasion resistant. This makes them more durable (though not indestructible. Eventually, they will also need attention). It also makes them difficult to simply recoat with a fresh coat of polyurethane of choice.
All such coatings must be abraded or scratched up enough to gain a mechanical bond. Since the coating is resistant to this, simply buffing and coating as per a site finished floor won’t be adequate.
This also makes a complete sanding a refinishing much more difficult. It requires twice the amount of sanding as a site finished floor. So, be aware, this is a tough job and I would suggest you have someone who knows how to sand with professional equipment and understands how to deal with a factory finished floor do the work.
The first thing that has to be done is to break the tension on the surface of the coating. It is not to flatten the floor, remove the micro bevels or even all the finish. It is just to scratch into the surface and open the coating. Sand it with a finer grit first; 80 or 60 grit.
Then you have to start flattening the floor, removing the micro bevels and the rest of the factory coating. You can go to something rough like 40 grit. I never went to anything more extreme unless extreme circumstances warranted it. But this has to be done on an angle, say 20-25 degree. It is huge work.
When all the finish is removed along with the bevels and the floor is flat, you can start sanding in the direction of the grain, stepping up your grit selection to fine grits. You could start with 50 or 60 then go to 80. The perimeter will be easier but still tough. I would finish with 100 grit on the edges. Not finer than that. The idea is to make sure all heavy sandpaper scratches are removed. Go to 80 or 100 grit on the big machine, sanding the final time after the edging is completed. Then you need to use 80 grit on an orbital or random orbital sander and remove the shading mark left between the big machine and edger and hunt for any edger sanding marks. Polish everything with a 100 grit screen disk, vacuum and continue to finishing. Sounds like fun doesn’t it?