A horse trailer is a vital piece of equipment for any horse owner. These trailers endure weather, road muck and horse-related debris throughout their lives. The floor of a horse trailer takes an incredible amount of abuse and can fail catastrophically if not properly maintained. Eventually, maintenance will lead to replacement, in whole or in part, of the wooden parts of the floor.
Remove the old floor by removing any rubber matting that might be on top and unbolting the wooden pieces. If the bolts refuse to come loose, use an angle grinder to cut them out. Save the bolt pieces so they can be matched for replacements. Pry up the old wood and discard.
Clean the chassis of the trailer and repaint if necessary. You may not have the opportunity to do this kind of maintenance for a while, so be sure to be thorough. Check for any needed structural repairs.
Cut 5 cm (2 inch) galvanised weldmesh to fit the floor of your trailer. This step is optional, but will provide a backup plan in case a hole were to appear in your wooden floor. Better for your horse to step onto mesh than onto nothing. Tack weld the mesh onto the chassis of your trailer or have a welding shop do the work.
Cut your new floor out of 1.8 m (3/4 inch) marine plywood, taking care not to place joins directly under where your horses will be standing. The amount of plywood and sizes of cuts will vary based on your particular trailer. A two-horse trailer might use as few as three sheets.
Replace the bolts through the chassis, sandwiching the mesh between the plywood and the chassis. It may help to predrill your bolt holes to ensure proper alignment. Countersink the bolts so that nothing catches on them. Drill 2.5 or 5 cm (1 or 2 inch) holes in each corner of the trailer floor to allow for drainage.
Paint the plywood floor with bitsumastic emulsion and continue to paint up the wall at least 5 cm (2 inches). Several coats will seal better than a single coat. Once the bitsumastic emulsion coating is completely dried, fit the floor with premade rubber floor mats or cut your own from 2.5 cm (1 inch) scraps of hard rubber.