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Yes, you can still coat floors in winter.

coating in winter

Trust us. We're in Minnesota.

 Pete’s is based in the Minneapolis/St. Paul area. We know cold. We know months of closed windows. We know the pain of hauling equipment through the snow. 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 now:

  • 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 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. Read more about the Bona line of waterborne polyurethanes that we recommend.

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.  This 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. The brand we prefer is Rubio Monocoat and you can read all about it here.

Ranked in ascending order of odor:

Rubio Monocoat 0g VOC per liter      
Bona Finishes 100-180g VOC per liter
DuraSeal Quick-Dry Sealer or Polyurethane 450-525g VOC per liter
Waterlox Original Sealer 614g VOC per liter

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” sidebar at right).
  • 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 about four 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 move dust around.
  • 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.