Pig shelters do not need to be anything super fancy. You can usually create something from extra wood that you have around the farm or repurposing things you are no longer using. We live in Texas where we have very hot dry summers.
I like to make A-frame shelters that are open on both ends. They provide shade in the summer and can be closed on one end for the winter. In the summer we position the shelter to have the sides facing east to west to protect them from the sun. Then in the winter we flip them so the sides are facing north to south to protect them from the cold north wind.
The main thing is that your shelters for your pigs are draft free and dry. I provide straw to my pigs for bedding in the winter.
Port-a-hut
We recently bought some Port-a-huts farrowing shelters. These were pretty affordable and once you get them out in the field they are not too difficult to move around. The back you can bend down to vent them during the summer and in the winter it tied back up to keep them closed.
