Yes, you can still refinish hardwood floors in winter.
Trust us. We’re in Minnesota.
These all seem like good arguments for waiting until spring to refinish your floors.
But don’t be so hasty.
There are several reasons for doing it during the winter:
- The low humidity of heated, winter air makes floor finishes cure predictably and on time.
- It’s winter; you’re already cooped up inside so you may as well do something
- Sanding is sweaty, physical work – you will suffer less if you do it when it’s cool. Sanding in July is miserable.
- Smart people in MN rent sanders in the winter because machine availability is better
But what about the ODOR?
It is true; many floor finishes still use mineral spirits as their solvent, and the smell of that chemical off-gassing from your floor is noxious.
But this can be avoided: in winter, choose a less smelly finish. And you do have choices!
Water-based finishes smell less and, contrary to popular belief, are often higher in quality than more traditional oil-based products. When in doubt, check the Volatile Organic Compound level of the finish you want to use. The higher the number, the harder it will be to breathe while it dries.
And remember that you are applying at least three coats of most finishes, so the smell will persist for at least those three days, and up to two weeks after that.
This is not just a one-hour problem, so if you have to sleep in the house during the any part of the coating process you will suffer, possibly permanently.
Our lowest VOC polyurethane is Bona’s Traffic HD with 110g per liter of VOC.
So, a typical 500sqft job with three coats of waterborne polyurethane will put roughly three pounds of petroleum byproducts into your home.
By comparison, typical oil-based polyurethane on the same job will leave about fifteen pounds of VOCs in the same space. Lower VOCs are better when you can’t throw all your windows wide open.
This doesn’t mean that solvent-based products are inferior – just that their odors are more difficult to ventilate during the closed-window months.
There is also another option: Hardwax-oil finishes.
These are zero-VOC finishes that are more like old-school penetrating oils (pure Tung or linseed oils for example), but have been engineered to be faster-curing and tougher than pure oils. These finishes are a joy to use any time of the year, but they are especially welcome in the winter.
Ranked in ascending order of odor:
As contractors, we sand and finish floors year round.
Here are our favorite tips for maintaining our work quotas even in the winter:
- Keep a shovel and a broom in the truck. Shovel a clear path from your vehicle to the door before you unload your equipment. Find the ice and salt it before you slip on it while carrying a drum sander.
- Change your damn shoes! Keep a separate pair of indoor-only work shoes or boots and change into them after you have hauled all your equipment through the snow.
- If your machines have been in a cold vehicle for more than a few hours, they will need more energy to start. Sit them next to a heat vent as you do your prep so the metal is closer to room temperature before you begin.
- When you must coat with oil-based finishes in winter, gap windows at the top, rather than the bottom. When cold air enters higher in the room, it warms slightly as it falls and doesn’t blanket the curing floor with a layer of cold air which can arrest the cure reaction.
- No matter what you are coating with, even in winter you need a source of fresh air that will bring oxygen to the cure process, and to allow air exchange that will let the evaporating solvents get outta there. So, at the very least, a gapped window in an adjacent room is imperative! And if that means you must turn up the heat so it doesn’t drop below 65 degrees while you have that window gapped, then turn up the heat (Read and heed the “Heat, Humidity, and Air Exchange” Bonus Tip below).
- If you are coating, but especially staining, over a cold basement, the cure time will be slower and the chances of the still-wet stain bleeding back into your polyurethane increase drastically. This can happen even in summer over damp basement or crawl spaces.
- Before you begin your coating preparations, turn up the heat to around 75 degrees. It will take about two hours to warm the air to that temperature. Then, right before you begin coating, dial the thermostat back down to 65 and you will have 2-3 hours before the fan kicks back on. This will keep waterborne finishes from “locking up” as you work and allow enough time for the finish to skin over before the fans start to blow dust around and into your finish.
Pete’s Bonus Tips
Heat, humidity and air exchange.
No matter what the season, both oil and waterborne polyurethanes need THREE conditions to cure quickly and thoroughly:
- low humidity
- air exchange
The air has to be DRY because heavy, moisture-laden air literally blocks oxygen from reaching the finish
It needs to be WARM because the chemical reaction that cross-links and cures the finish will not proceed below 65°.
And a constant but gentle source of FRESH, OUTSIDE AIR provides the oxygen that the finish must combine with in order to become a solid and fully cure .
Some tips for creating the perfect curing scenario:
If the interior temperature is likely to fall below 65° at any time during the coating or the first week after coating, turn on the heat!
Don't point a fan directly at the drying floor; it will force dust into the wet finish. Use a fan in an adjacent room like a bathroom or kitchen vent that is connected to the outside, and leave it on. In warm weather you can put a box fan in a window (blowing out!) in an adjacent room. In cold weather, box fans in windows will suck out too much heat - just gap the top a window in each affected room.
High humidity is the most difficult coating condition to deal with. Turning on the AC will bring the interior humidity down, but without opening windows, the evaporating solvents have no place to escape and fresh oxygen can't get in. But opening windows brings the humidity back up. Usually you simply have to resign yourself to longer times between coats and a longer overall curing time during the most humid months.
For oil-based polyurethanes, you should keep one window in the coated room gapped to 3” for two weeks.
What you should know about modern waterborne finishes.
Waterborne finishes have improved exponentially since they first appeared on the market.
Modern air quality regulations have encouraged manufacturers of waterborne polyurethane to step up their game.
Waterborne finishes are much more resistant to wear and solvents than they were even 15 years ago (please note that we're referring to respected finish manufacturers; inexpensive, big-box store waterborne finishes can still perform poorly).
They are also much less prone to foaming and will level better than they used to.
So, don't just categorically dismiss this class of finishes, but make a educated decision based on what we do know about them.
Five things to know about waterborne finishes
- Waterborne finishes, unless their container says otherwise, have no color. None. Especially compared to oil-based polyurethane. Even Amberseal can't warm a floor up as well as oil poly. There are ways to get around this - read about Bona's oil-based Dri-Fast Sealer designed for use under their line of waterborne finishes.
- You don't need to use a respirator for the waterborne finshes we sell, but that doesn't mean they don't contain toxic solvents. They just contain smaller quantities of them. People who are respiratorially sensitive or pregnant should still stay out of the property during the coating process.
- Waterborne finishes clean up with water; don't use paint thinner, turpentine or alcohol.
- Waterborne finishes are more weather-sensitive than solvent finishes. You'll find that waterbased finishes will take longer to dry in humid weather, but set up with disturbing speed on those hot, dry windy days.
- Don't let your waterborne finish freeze! Once it freezes, it's ruined.
We sell and ship Pallmann polyurethane in our online shop.
If you're in St. Paul or Minneapolis, drive on over and belly up to our counter. We stock most Pallmann finishes.
If you're out of state, you can get Pallmann in our online shop. We happily ship all the Pallmann products (except in the very worst of the winter - these products are not freeze-thaw stable, so be careful in Feburary, no matter whom you buy it from).
Pall-X 96 Nexgen available in satin, and matte
Covers 450-500sqft per gallon. Gloss and semi-gloss available by special order.
Pall-X Power available in satin, and matte
Covers 450-500sqft per gallon. Gloss and semi-gloss available by special order.
Pallman floor cleaner spray, 32 oz.
A great, all-purpose cleaner for any polyurethane-coated hardwood floor.
Pallmann Magic Oil Care, 32 oz.
Formulated for periodic maintenance of hardwood floors finished with Pallmann Magic Oil.