You have very few choices. No type of vinyl will work...no vinyl plank, vinyl, Luxury vinyl, etc etc etc. No laminate, no wood. Possibly a floating vinyl fiber floor with a large expansion gap could work but will not be manufacturer approved. Carpet or Porcelain ceramic tile will work and can be warranted. That is really about it. This is why most have carpet. Sorry. Other posters may disagree somewhat, but you can take this info as fact. We sell it all and have seen it all. We had 5000 sq ft of vinyl plank blow up 6 weeks ago because it was laid without proper heating source installed yet, than it got warm and it lifted 3 inches off the floor in spots. Tore it all out. Good Luck.

As Tibbrix said, I wouldn't worry about it. I bought an inexpensive ($50), very large canvas oil painting (off eBay) to cover an outdoor mirror, in an uncovered area. The painting hung outside in the hot summer months, rainy season, and very cold winters this past year without any sign of damage until the wind blew it off the mirror and it split over a wrought iron chair. Boo! This post was edited by newhomebuilder on Mon, Jun 23, 14 at 16:00

As an appraiser, I see you having two issues, which option will be the best value and which option suits your needs? The basement will provide the best return on expense. The reason is it will be heated and can be counted as finished living space below grade. The three-season room will be designated as unfinished area such as a deck or porch and valued accordingly.. If all of the other units have a basement and your unit doesn't, it may be harder to sell. Flip that statement to if all of the other units have a three-season room and yours unit doesn't it may be harder to sell. Having said that, you need to install whatever best suits your needs and desires. Life is too short. Put in the item that you think will improve the quality of your life.

I had a Vermont multi-size/color slate floor in my kitchen in the dorm apt in Maine. We bought the slate at Lowe's in Portland - it was about $1 per sq ft at that time. I have never liked a kitchen floor as much as I did that slate floor! With the multi-color/size tiles, it did not appear terribly dark. It was wonderful when the dogs (or my husband) came in with snow on all their paws (I had 5 dogs at one time up there, plus the "big dog" - i.e. my husband). It just dried and that was it. Once a year, my husband washed and sealed the floor. Other than that, I just used a broom on it. I have a sun porch and if the slab had not cracked at some time over the years, cracking the brick on top, I would put Vermont slate down in a heartbeat. I just can't deal with trying to level the slab on a 70 yr old house, and the slate will crack if I don't. If you don't care for multi-color, go with a natural green slate - it's a very pretty color. I like my sun porch to have flooring where I need not worry about water. I bring in many, many plants to winter over on the porch, and I have a spigot and coil garden hose to water all these, and I need to allow the water to come out the bottom of the pots (no saucers - pots too large). Slate would work very well.