Stock trailer floors: where the rot actually starts

A stock trailer rusts from the inside out. By the time the outside looks bad, the parts that carry the load have been working on it for seasons.

Why the floor goes first

Manure and urine are corrosive and they sit. Add washing, add road salt in the shoulder seasons, and add a floor that never fully dries because there is a mat or a bed over it, and you have the worst environment on the trailer.

The order things fail

• Floor sheeting, usually starting at the low points and around the drains.
• Cross-members under the floor, which you cannot see without getting underneath.
• Lower frame rails, from the inside face outward.
• Lower side sheeting, which is what you finally notice.

What blasting shows you

Blasting does not repair steel. It removes everything hiding the condition of it. On a trailer that has been going a while, that means holes appear where there was scale, and thin sections start to sound different.

Better to find it in January with time to weld than in May with cattle to move.

The decision it forces

Once it is bare you can make an honest call — weld and coat, or stop spending. Either answer is better than paint over scale for another two years.

Trailers working the country between Medicine Hat, Seven Persons, Irvine and Bow Island spend a lot of the year on gravel and a lot of the winter carrying salt off the Trans-Canada. Both accelerate exactly the corrosion described above.