This is in a house I made. 100%. It is a 13x10 rectangle with a flat roof. I have upgraded everything to Stone. The walls are glass blocks. It is one square away from the Frozen biome so I get the weather. It has stopped all of the weather rain or snow. It's entirely possible I just by accident have an oriented just right so it doesn't rain inside or snow inside. It is parallel to the snow biome.Last I noticed several Alphas ago, this depended on the shape and ignored rotation. So half blocks would always let the rain in, even if they covered an area with no gaps. Rain would also come through hatches, because the game wouldn't bother to take into account whether the hatch is open or closed.
Wish I'd have thought of that.In my case, I only have problem with roof and rain when I put a hatch to access the roof. Rain would come in a certain number of tiles around the hatch, something like a cone with the hatch in the center. This has been the case for as long as I can remember (I started playing with Alpha 15) and is still the case with Alpha 19.
My solution is to build a small roof thingy over the hatch on the roof. That prevent any rain from getting inside my home base. Here's a screenshot of what I mean.
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