Which type of polyurethane is better for refinishing hardwood floors - water-based or oil-based polyurethane?
We offer both options, but I strongly prefer oil based poly over water based because:
1. It looks better
2. It lasts longer
3. It costs less.
So, it seems like a no brainer, right? Well, usually it is a simple decision, but there certainly are some exceptions and different customers have different needs.
So, let's delve in a bit further.
Benefits of oil-based polyurethane.
1. Oil based polyurethane looks better. It has a more depth - both in color and shine and it looks the way we expect hardwood to look. Water based polyurethane has both a duller color and a duller finish. I wish I had some good pictures to demonstrate, so instead I'm going to link to the trusted authority in hardwood from the National Wood Floor Association water based poly vs. oil based pictures on domestic wood species.
Please check out the above link and you'll see how different the colors look - the water-based polyurethane in on the upper left; the oil based poly on the lower right. It's pretty dramatic. The other issue when it comes to appearance is that over time the polyurethane amberizes and darkens a bit...usually giving it a richer look while the water based poly just continues to get duller over time.
2. Oil based polyurethane lasts longer than water based. There is no contest on the durability between the 2 options. Water based polyurethane has lower VOC's - which is a bit of an environmental benefit (more about that in a moment) - but because it has lower VOC's (Volatile Organic Compounds), it doesn't last as long. Water based poly is thinner, and you often need 4-5 coats to equal the durability of 3 coats of oil based.
While I do not have detailed analytical studies, most customers who call me to refinish their floors and previously had water based poly, call me after 5-6 yrs vs. most customers that call me to refinish their oil based polyurethane call me at around the 10 yr mark. And, at those points in time, the water based poly looks way worse than the oil based - in fact, it's usually peeling off and the hardwood is starting to look gray. What' s also interesting is that almost all of my customers who have had water based polyurethane tell me they would NEVER do it again. They felt mislead by their previous flooring contractor. While sanding and refinishing is not terribly expensive, it can be rather inconvenient if you live in the home. You need to move all the furniture out and often go away for a week. So, if you're going to go though the hassle of refinishing your floors, I recommend doing it right so it last longer.
3. Oil based polyurethane cost less than water based. The water-based material is more expensive, so often you will pay around 10-25% more. But, on top of the initial cost, you also need to consider that you will need to redo the whole job sooner...you will probably redo them almost twice as often.
Now, there are several benefits to water based polyurethane and in some circumstances, water based poly is a great option.
Benefits of water based polyurethane:
1. Water based polyurethane dries faster. In my opinion, this is the largest benefit of water based polyurethane. Usually, water based jobs can be done in 2 cays and you can walk on it that night where as oil based can take 3-5 days (pending on humidity) and you need to wait at least 24 hrs before walking on them. This option can really make sense for commercial businesses such as restaurants or stores as longer drying time means the store is closed, and there is a true business cost to that. But, for regular homeowners, usually, it's worth waiting the extra 2-3 days in order to have the job last longer.
I have many customers who are in a rush to move into their new home, but I always recommend that it's worth delaying move in by a few days and get their floors done right. If they don't, they will spend more time and money paying for this later. For customers already living in their home, I recommend that they do this while they will be away for a while. I would rather wait 6 months for their next trip and have them pay less and do it right with oil based. Why do I feel this way? Because they will be happier and save money, and I rely on happy customers who recommend me to their friends and come back to me years later for the other flooring in their home.
2. Water based polyurethane doesn't smell as bad. Because of this, many co-ops are now requiring their homeowners to use water based poly. I think this is a bit of a shame, but I understand it due to all the neighbors. For regular stand alone home, it will not make much of a difference to your neighbors, and I will also point out that both water based and oil based poly smell, and I still recommend that customers go away or stay somewhere else while this work is being done.
3. Water based polyurethane is a bit better for the environment...but it does depends on how you look at it. Since water based polyurethane has lower VOC's (Volatile Organic Compounds), it is a bit better for the environment. As mentioned above, the VOC's are lower not non-existent. And, importantly, this environmental benefit only has an impact during the DRYING time. Once the poly is dry, there is no difference in smell, off-gassing, etc. And, yes, I did validate this with the manufacturer - and they offer both water and oil based (and they make more money on the water based so they have no reason to mislead here).
Now, the skeptical New Yorker in me always sees both sides of the equation, so I will point out that while water based is a bit better for the environment, remember that it doesn't last as long and the floors will need to be redone in a few year, thereby prob. eliminating that benefit and furthermore, leading to an ultimately earlier demise of the wood which in turn will result in more cut trees, so everything has a flip side.
So, in most circumstances, I believe that oil based polyurethane is a better option vs. water based polyurethane for refinishing your hardwood floors.