This is a very common question I have heard over the years, “How many times can you sand my wood floor?” There are a number of variables that we can talk about for a little bit that should help you.
1) What type of flooring is in your home?
Wood flooring is milled in a variety of thicknesses. In order to make sure we just level the discussion between engineered flooring and solid wood flooring, the area that is capable of being sanded is the wear-layer. The wear layer for solid flooring tends to average about 5/16″ thickness. For engineered flooring, this can vary to as little as 1/32″ to 5/16″. This is why I encourage all of you to really evaluate your engineered wood floors at the time of purchase. We did a video on this a while ago that you can view here.
If you have flooring with a very minimal wear layer thickness 1/16″ or less (or a hand scraped engineered floor), then honestly your best option is total replacement in most cases. We have successfully refinished floors with no greater than 1/8″ wear layer, but this requires a cautious approach.
HOW DO YOU EVALUATE THE WEAR LAYER OF A FLOOR?
This can be done by either pulling a floor vent and looking at your floor from the side. All of the wood that is above the tongue of the board is yours to sand. If you have floors on concrete, then either try to pull a transition strip at a junction with carpet, linoleum, etc.. or look at a piece of the original flooring. Sometimes, you cannot determine the wear layer of a floor if you cannot determine the name of the manufacturer and the products specs. In these cases, I recommend you do a test sanding in somewhere like a small closet in a corner with an edger. Although this is risky, the affected area will be out of sight.
2) Sanding skills and Approach are Essential
My industry is one that lacks an established set of benchmarks for knowledge before you can make it your career. Moreover, many contractors who have only been educated by the generations of contractors before them tend to stick to the same sanding procedures that worked in the 50’s. Guess what? In the 50’s virtually every wood floor in any home in America was solid floor with a thick wear-layer. Many of the old school sanders in this business believe in starting with extremely coarse grits (36grit or 40grit) and cutting floors 3 times or more with a belt machine in order to achieve a flat floor. With the luxury of a 5/16″ wear layer, this is an okay method because who cares if you remove 1/8″ of sanding life? You still have plenty left.
DON’T LET THESE BONEHEADS ANYWHERE NEAR YOUR THIN WEAR LAYER ENGINEERED FLOOR!
If you know that you have a thinner wear layer (such as 1/8″) then it is imperative that the floor be sanded only one time with a belt machine using no more than 80 grit paper on a lighter head pressure. Although this may not remove every little dent and ding in the floor, these can be filled with something like a Mohawk touch up filler. All you are trying to achieve is a complete removal of the old finish. Proper hard plating of the floor after the belt machine will give the floor the desired flatness. Preserving the look of your floor by not sanding through the veneer is more important that anything in this case. The cost of removing and replacing some wood floors is quite high in certain circumstances.
The National Wood Flooring Association specifically references the question in this blog post, and they default to the skill of the operator of the sander as being most pivotal. In addition, the NWFA generally does not recommend refinishing wood floors with a wear layer of less than 3/32″.
3) What About Sandless Refinishing?
I’m sure that the idea of refinishing wood flooring without sanding conjures up ideas with the public of being so clean and effective. This procedure has been implemented in a few different versions with franchises such as NHance, Wood Doctor, etc… and if you search online or talk to a neighbor, you will find that the promises outweigh the value. In sandless refinishing, the company will typically clean the floor and prepare it for chemically bonding a new finish layer. Afterwards, they apply a tinted finish coat that will obscure the look of the scratches and restore the color somewhat. This procedure can work with some success, just be aware that the procedure is not likely to flatten the floor at all, so your dents and dings will remain.
If you have talked to your friends or neighbors, then you’ll likely hear people talk about “buffing and coating” a floor, which is a very light sanding. This procedure is akin to sandless refinishing, but involves a very mild abrasion of the existing finish coat in order to remove cursory scratches and provide a “tooth” to which a new finish coat can adhere. Sandless refinishing relies more on chemical processes to create adhesion for a new finish coat instead of a mechanical bond. We have done lots of clean and coats to floors, some of which had a wear layer that was unable to be sanded. These procedures will work well.
In the end though, make sure that you prepare a list of questions and discuss all options. I’ve been told by many industry colleagues that many sandless franchises really push their system because they are highly profitable even though the results are not long lasting. An honorable contractor will help you determine which method is possible and provides the best value.
I really hope that you have learned something here, but if you are still confused, email me or call me. I am absolutely glad to help you in any way possible.
A great resource for homeowners in regions where we are unable to provide service (outside of Sacramento, CA) I encourage you to search for an NWFA certified professional with the “sand and finish” certification. These individuals are held to a standard and code of ethics as contractors and will help you make a good choice with integrity. Do not confuse an NWFACP contractor with a general NWFA member, which means they simply paid to be a member.