Skip to main content

Horse Trailer Repair: Floor Boards

  • Author:
  • Updated date:

Ms. Millar has had many books published online and in print. She learned how to bind her own books to save money on publishing costs.

Wood Rot

Wood Rot

Horse Trailer Floor Replacement

The floor in a stock/horse trailer does not last forever. It must be replaced before it rots. When the wood floor rots it can break through anytime when weight is applied to it. Tragedies like a floor giving out can easily be avoided. With a few tools and some instruction, you can replace that rotten floor!

Rotten Floor Boards

There is nothing that I can think of that could be more horrifying than when rotten floorboards give way under the weight of a horse and the horse falls through.

I've been hauling horses for thirty years and never had a floor buckle under a horse, but I have heard of it happening. Every situation I've heard about involved rotten floorboards. Dry rot will rob wood of its integrity while the wood appears stable.

Horses weigh anywhere from 800 to 3,000 pounds. That is a lot of weight; weight that doesn't stand still when it's traveling. There's stomping, and jostling, the entire ride. The floor must be strong to avoid a breakthrough.

If a horse's hoof does break through a rotten floor, the damage is unbelievable to the horse. This is a huge tragedy that can be totally avoided by replacing the floor periodically.

Check under the mats periodically. This wood is unacceptable to transport anything!

Check under the mats periodically. This wood is unacceptable to transport anything!

If floorboards show signs of weakness such as grass or fungus growing, it's time to replace the boards.

If floorboards show signs of weakness such as grass or fungus growing, it's time to replace the boards.

Acceptable and Unacceptable Flooring

There are a huge variety of products that a floor can be constructed with. Some are safe, others are downright unacceptable for a trailer that will transport horses or any livestock.

  • Acceptable: Steel, Aluminum, Treated Wood
  • Unacceptable: Plywood, Pressed Wood, Untreated Wood

Consider taking some time to read more information about wood preservation.

Stock Trailer Floor Difficulty

You will find detailed instructions on replacing the floorboards, also referred to as planks. The trailer we are replacing the floorboards on is an old, steel, gooseneck, with a wood/plank floor. This type of trailer is also called a stock trailer.

Replacing the boards is a straightforward task. It does take some muscle; the boards are heavy, and removal of the old ones can be somewhat difficult. Placing the new ones is not as difficult as removing the old ones, but they do take some adjusting which may include a sledge, or other heavy hammer.

  • Process Difficulty Rating: Easy.
  • Physical Labor Difficulty Rating: Medium.

Gather Your Tools

It's helpful to gather your tools in advance.

  • Flooring material (treated wood, steel, etc.)
  • Measuring tape
  • Straight edge
  • Cutting device (hand saw, etc.)
  • Grinder
  • New screws
  • Screwdriver
  • File
  • Drill with bit
  • Sledge or another type of heavy hammer
Trailer Floor Support (Joists)

Trailer Floor Support (Joists)

Replace the Old Wood

The old floor needs to be pulled out. If the wood is completely rotted like the planks in the photos, then you can simply rip them up by hand. I was able to rip up the majority of the boards in this trailer with a gloved hand. Towards the forward section, the boards had less rotting and I had to use my skill saw to cut the plank into sections. Once a plank was cut into sections, I was able to pull them out. Before making any cuts, read through the following steps, then proceed.

  1. First, check underneath to locate the steel floor joists. Then using your saw, make sure you don't cut through the steel support joists under the wood, and cut the boards one at a time.
  2. After they are cut, remove the screw securing it to the steel joists. If you can unscrew the screw, great! If they are rusted to the steel, you will need to grind the top off to get the board out (Then grind off the rest of the screw after the board is out). Don't damage the steel joist when grinding off the screw!
  3. Now you should be able to pry the board up with a crowbar, or use your sledge hammer to tap it out of its slot. A large screwdriver can prove handy at this point to wedge between the boards.
  4. Move on to the next board and repeat until all the boards are removed.

Now that all the boards are out; inspect the steel floor joists thoroughly for signs of rotting or rust. If either is found you need to remove it with a wire wheel before doing anything else. Inspect and remove all rot spots, or rust, then apply a coat of rust-resistant paint. Allow it to dry for a few minutes and apply another two to three coats. If any of the floor joists have rust that is pitting the steel, take the trailer to a welder to reinforce that joist, or all the joists.

After the paint has dried you are ready to lay the planks.

  1. Measure the length of the area that each board covered. Measuring the old boards you removed will not give you an accurate measurement. Wood shrinks as it ages, it won't measure the same as it did when it was new.
  2. If there is a lip the flooring slid into, or under, on each side subtract 1/2 inch or so from the total length or you won't be able to get the floor sections back in. Take your measurement and apply it to your chosen flooring and cut to length. (Remember: Measure twice; cut once).
  3. If your flooring is treated wood, wear a mask to protect yourself from the airborne pesticides produced by the sawing.

The following photos walk you step by step on how to put the boards back in.

Placing Flooring and Special Cuts

  1. Place your cut wood, steel or aluminum as shown.
  2. Tap on one side until the board is square with the trailer.
  3. Tap evenly on the board as you move it along the rails to the forward edge of the trailer.
  4. Tap the board securely into place.
  5. Do the same with the next board leaving a nail width gap between the boards.

Follow along with the next set of photos.

Special Cut

A special cut, for a horse trailer, doesn't involve much. The wheel wells are where you may need to cut a stagger formation, or a notch. Below explains special cuts at the wheel well. At this time go to the opposite end and install the boards exactly as you did for the forward section working your way to the center. At the wheel wells:

  1. Measure and cut the pieces between the wheel wells.
  2. Cut your two special cut boards for the ends of the wheel wells.
  3. Place the first special cut board and follow with the rest of the shorter boards between the wheel wells.
  4. After the second special cut board is set then place the boards left out earlier.
  5. The last board will need to be filed on the ends. Then lay one side into the lip and hammer firmly until it is fully seated under the lip. Then wedge the other end under the lip. This can prove to be challenging. File off more length if needed to get the board under the lip.

You're almost done. Set the gap between the boards. I used nails, one at each end of the boards, to set the gap. The nails were the perfect width and the head stopped them from falling through while I screwed in the screws. Take the new screws and, if possible, locate the old hole and screw the new screw into it. If it is not possible then drill new holes and screw in the new screws, two per board.

You Did It!

Now you are done! You may have saved a life with this task, good job!

Further Information

After a concerned comment from a reader, I decided to add photos of a completed floorboard with horses loaded.

The reader was concerned that the horse would have their front feet on one board when loaded and the "sideways" installation was dangerous.

The photo's below should clearly indicate that not only are all four feet of the horse supported on individual boards but they also have a steel beam under the floorboards in which the horse has added support.

Thank you for reading and commenting!






This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Questions & Answers

Question: Should floorboards be placed lengthways or sideways?

Answer: Floorboards should be placed sideways. This will give the best support.

Question: This is a follow up to the question on how to place the floor boards. Doesn't it all depends how your angle iron supports are secured to the trailer. Some have the boards going lenthways, others have sideways?

Answer: Yes, you are absolutely right. I have personally found most trailers floor boards run parallel to the gate.

© 2014 Joanna