We had a builder do the work and after all these years I really don't really remember what type of insulation was used - though I'm certain there was some. The old open porch was entirely removed and replaced with the new three season porch so they most likely would have used whatever is typical for exterior walls. If we want to sit out there on a winter day we just turn on a small space heater for a bit and it's very comfortable. On a sunny day we don't even need that.

Well, after looking into it a bit I agree that it would be good to insulate the area. But which is preferable, foam panels or fiberglass? If fiberglass is recommended, should it be placed between the roof joists or the ceiling joists? And how thick? If foam panels are recommended, they come in a multitude of thicknesses and types. What's recommended? I've searched for this online and didn't see much about insulating seasonal rooms.

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.

shead - I sort wash loads into 4 categories: whites, lights, darks, jeans. On very few days would I want to put everything I'm wearing into the same load. And obviously, lives are different. DH works on a farm. All of his work clothes (which can amount to more than a load per day in the winter when he wears multiple layers) can all be washed together. It will be FAR more convenient to wash his clothes in the master closet and put immediately away than lugging them to the other side of the house and back again to put away. 90% of my things can be washed together as well.