Dry box trailer wash out in cold weather?

If the water freezes it can damage the wood flooring. It gets into every nook and cranny and you won't be able to dry it out.
A little water between the boards and the wall or between the boards them selves, or seeping into plywood, will freeze, expand, and damage something.
I wouldn't do it if the OAT is below freezing.

 

hauling trash

 

I don't ever recall washing out a van.

 

Have to let it dry, and sweep it out. Washing a metal reefer is one thing, but a wooden floor, will rot. Kind of why it's called a "dry van".

 

Me neither, swept out many a one though. The worst time I remember was hauling chip trailers from the sawmills to the pulp mill in the winter. After dumping the load, the chips would freeze against the walls, sometimes a foot thick. Talk about a pain in the ### getting that cleaned out when it's below zero...

 

I did a plant load one time where they set them on the floor wrapped with wet & muddy burlap fabric. I bought a 10' X 50' long roll of visquene and rolled it out on the floor before they set the stuff in there. It worked out pretty good. I just rolled it back up after they were done and threw it away.