I have not gotten the Seasons EP yet and I have a question about the weather and houses. In The Sims 2 you always had to place floor tiles over any room for keeping the rain and snow and cold out of their houses. Which meant you couldn't use attics as living space.

How is TS3 Seasons done in this regard? Is placing a roof, covering every inch of the house, enough to keep the Sims warm, cozy and dry? Can you live in an attic in the winter... In other words, what are the rules for building weather proof houses? I tried :google: but couldn't find any 'rules'.

Thanks for your observations. :-)

I have a house in Lucky Palms, a dock house. And even though I have a covered patio area, because it's not enclosed, snow does drift in onto the patio floor. It won't entirely cover it but sometimes if it snows heavy enough, it will pile up under my covered patio and certain things become buried.
Also, if a room isn't completely enclosed, your sim will still be affected by the weather - overheat if hot, freeze if cold.
Rule of Thumb ( as far as I know and have played) If you have a space with roof, but no walls, your sim is exposed to the elements.
If you have a four walls no roof, room is not enclosed and your sim is exposed to the elements.
Four walls and a roof, or ceiling tiles, your sim is protected against the elements.
Rain does not drift sideways onto a covered patio but puddles may get large enough to floor somewhat under the covered patio, same with leaves. Leaves seem to fall in a predicted pattern around trees so if a tree is close enough to a covered patio that is not fully enclosed, leaves end up under the patio.
Hope that helps. If you have anymore questions let me know.

The walls of a gable roof leave the room somewhat open to the elements. You'll get a slight dusting of snow on the floor, and your sims will wear jackets in there. For example, I had to add floor tiles to Amy Bull Bob's house in Twinbrook because I found everyone freezing in there.

Oh, this is great info. Thank you both very much. Will copy it to my PC for later use.