Late last fall, we had a sunroom built on our nhouse, and we're trying to determine what type of flooring should be installed. We live in Winnipeg, Manitoba, Canada, so the climate will definitely be a factor.
The flooring is plywood, with metal flashing around the outside edge at the walls.
In January/February, the temperature can reach -35C (-31F). In July/August, the temperature can reach +35C (95F). The sunroom is south-facing, with all glass/aluminum walls, so the air temperature inside during summer will be higher than that. In winter, the sun won't have any significant moderating effect on the temperature.
Compounding this, we have a dog that we let out into the back yard every day, so we walk through the sunroom two or three times every day, winter or summer. In winter, this lets a lot of moisture into the sunroom, which condenses on the windows. As we get closer to spring, the moisture melts and pools at the edges of the sunroom, and wicks onto the plywood if I don't mop it up quickly enough.
We have been told that some flooring types won't be suitable (linoleum and vinyl, I think) because they get brittle in our winter temperatures. We were expecting to have to use some outside carpet, but one flooring company told us we could use laminate flooring. I'm getting a sense that the contractor is a bit of an amateur, though, and I've read that laminate flooring contracts in the cold, so I would expect it to shift as we walk on it.
Can someone please recommend types of flooring that may be suitable for our conditions? I plan to have whatever we choose professionally installed (I'm not very handy).
To clarify, the sunroom is a raised structure with insulation in the floor and ceiling. It is an unheated space, and with the temperatures we get in the winter, no amount of insulation will help an unheated space in January. The structure seems quite secure, with teleposts of some kind on top of concrete footings.
EDIT: Not enough reputation to comment on my own question. My installation does not have any sort of pan. The walls are mostly glass with a metal frame, which stands on metal flashing. The flashing extends 5" from the glass/metal walls, and the remainder of the floor is plywood. Since we open the door from the kitchen several times a day to let the dog in and out, the air in the sunroom, which would normally be very dry in the winter, ends up having a lot of moisture in it, which condenses and freezes. In the spring, as the sun becomes more intense, the condensation melts and pools at the base of the wall. I mop it up every day to reduce the amount that can condense that evening, but a couple of times it has reached the plywood before I got home. My thought was to install whatever flooring type is best, then put a barrier of some sort (metal or plastic edging), then add a bead of silicone along the entire edge, to force the water to stay on the flashing until I can mop it up.
Best Answer
Your best option is sheet vinyl. Next to that would be tile or concrete.
Most other flooring has seams which will eventually leak. Yes, you can place vinyl tiles, or even laminate flooring, if you appropriately glue/seal all the seams. Eventually the seams will leak, and in the case of laminate surface scratches must be sealed immediately to avoid damage to the laminate below the waterproof surface.
A single sheet, if possible, will provide continuous leak protection across the entire floor surface. If it's too wide for a single sheet, then a single seam is easier to keep sealed than the multiple seams found in other flooring choices.
Tile and concrete are both good options as well. Regular maintenance and upkeep will keep them in good waterproof operation for the life of the house, while vinyl will need to be replaced every decade or two.
Even though it's designed to be an unheated space, you should consider adding a vapor barrier and insulation to the flooring area. This will reduce the likelihood of later rotting or water condensation.
Keep in mind that outdoor carpet requires a sealed or well-draining surface. Your current plywood would have to be treated and sealed for the outdoor carpeting to be useful. The carpeting alone won't prevent damage to the subfloor - it will only avoid damage itself when exposed to water.
In your situation you need to protect both the flooring and the subfloor.
Regarding the cold temperatures, newer vinyl floors are much more flexible and resilient even in the fact of extreme cold weather. You'll need to specify that both the flooring and the adhesive be tolerant to freeze-thaw cycles.
Be certain that your subfloor is substantial and secure. Cracking occurs where stresses increase significantly on one area of the floor. As long as the vinyl is well-adhered to the subfloor, and the subfloor is relatively stable, then the stresses from expansion and contraction will be spread evenly across the entire surface. While these forces are large, they won't overcome the strength of the vinyl. If the subfloor develops a large gap, then the stresses in the vinyl would be greater around that gap and that's where a tear might start.
So your flooring really starts with a good, stable, strong subfloor. What you put on top, then, will be fine as long as it can deal with the water exposure.