Cold weather work
Can a floor be coated in cold weather?
A floor can be coated in cold weather, but what governs it is the temperature of the slab rather than the air, along with the humidity and the dew point.
The short version
- The slab temperature governs it. The air temperature is the easier reading and the less useful one.
- Concrete holds cold. A slab stays colder than the room above it long after the heat has been on.
- Humidity matters as much as the cold, because a surface near the dew point can carry moisture you cannot see.
- These are label conditions for the exact product, and they are not the same product to product.
What governs a cold install
The reading that matters is the temperature of the concrete, not the temperature of the air. A slab in the southwest Twin Cities metro is a large cold mass sitting on ground that has been frozen since the fall, and it stays colder than the room above it long after the heater has been running.
So the answer is a reading rather than a season. Somebody puts a temperature gun on the slab in several spots, checks the air and the humidity in the room, and compares all of it against the conditions the product label calls for. Every product has its own window.
Humidity and the dew point
Cold is only half of it. The other half is how much moisture is in the air and how close the slab surface sits to the dew point. A surface near the dew point can pick up a film of moisture you cannot see, and a coating going onto that film is a coating going onto water.
This catches people in the shoulder seasons more than in the middle of winter. A mild damp day after a cold night puts humid air over a slab that is still cold, which is the setup for condensation on the floor. A hard freeze with dry air behind it is often the easier week to work in.
A closed garage and an open patio
An attached garage with the overhead door shut and heat in it is a room, and a room can be brought to conditions and held there while the coating goes down and while it cures. A patio, a driveway or a pool deck in the same week is a different question, because outside the weather is the conditions.
If the room cannot be brought to conditions and held there, waiting is the cheaper choice. A coating put down outside the label conditions can look right the week it goes in and let go a season later, and the removal is the expensive half of doing the floor twice.