Along with our hoop houses, a few years ago we found a new system for the hog shelters. A coworker found access to an old water slide. Serendipity struck, the person who had the tubes wanted them off his property and we found a great recycling use which should last for many years. The tube of the water slide was two halves bolted and sealed together. One of the tube halves turned with the open side down makes a small Quonset-type shed which is large enough for even a five hundred pound sow or boar to get into. The tubes are made of fiberglass and are thus water and wind proof . They are easily picked up and moved with a tractor front loader.
With a deep straw bed soon the ends of the tubes were producing steam from hog body heat and decomposing straw. Even at fifteen or twenty degrees below zero Fahrenheit the warmth is clearly discernible, as soon as you or a pig is inside the tube a couple of feet. I know this because several times I have crawled inside to add more straw. The sheep also liked them and the cows often bedded down by them as they cut the wind. They also make great farrowing huts.