What thickness steel should I use to build a new trailer door for a horse trailer?
Thick enough the horse doesn’t fall out. I would not use less than 1/8″ that would be a good start for the tube. Assuming it is a swing gate cover it with 22 gauge sheet metal on the outside and maybe plywood or rubber on the inside. If you use aluminum you will have to protect it from the dissimilar metals (steel and aluminum don’t like each other especially in that type of atmosphere, wet and poo). You would need stainless steel hinges and fasteners also. If you go aluminum hope you have the equipment to weld it, bolting only won’t hold.
