How to build a flatbed truck bed


If you want to convert your truck bed into flat bed, then you must be wondering how to build a flatbed  truck bed. Well to build your own flat bed you have to follow a few simple steps that include removing the old bed, cutting and preparing the material, layout and welding, cutting and attaching the lumber, painting and finishing the frame, and finally attaching the tail lights.

If you want to do it on your own, then make sure to arrange the following tools and safety measures so that you do not face any further hassles in future.

Required Tools

  1. Drill and 5/16″ drill bit
  2. Welder
  3. Reciprocating saw with metal blades or cutting torch
  4. Metal clamps (I used all the clamps I own)
  5. Tape measure
  6. Soap marker
  7. Circular saw
  8. Grinder with wire wheel (or wire brush)

Equipment for Protection

  1. Welding Gloves
  2. Welding Hood
  3. Cotton Clothing or Welding apron or jacket 
  4. Leather work boots

Visit to buy equipments for protection.

How much does it cost to convert a truck bed to flat bed?

We have made an estimation to provide a rough idea about the cost per the work done during converting truck bed to flat bread. The total cost will be around $450. Let us break up the price for individual expenditure made during the process.

  • trailer lights will cost $70
  • hardware/ paint may cost around $40
  • lumbar can be purchased at $90
  • stock metal will cost you around $250

Steps to build a FlatBed Truck Bed

Step 1: Remove the Old Bed

The first step to build a flatbed is to remove the tail lights. If your truck does not have any tail lights present aside from the temporary, you may skip this step.

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To remove the bed, you have to locate all the 6 bolts holding on a truck bed; two of which can be found near the cab and four will be found towards the rear of the frame.

You can use a pb blaster to help break the rusted bolts free. However, if you do not want to show that much patience, then you can cut the bed off with an oxy acetylene torch. You can also take help of the reciprocating saw to cut the bed free from the frame.

You can remove the plastic bed liner and cut through the bed with the torch to release the bolts. Moreover, you can use the torch to cut the bolts off and to remove the bed.

At this point, you can think about to do some maintenance on the frame while it is exposed. Just spray it off with a hose to remove the mud, and then use a wire brush and a chipping hammer to knock off the rust. The next step will be to put a light coat of primer to protect the frame. To complete this step, add a layer to the frame as per the instructions.

Step 2: Cut and Prepare the Materials

Required Cuts:

You will need the following cuts for building your flat bed.

4 – 6′ (2″x4″ rectangular tube)

6 – 10″ (2″ 1/8″ angle)

4 – 5′ 8″ (2″ 1/8″ angle)

After you cut all the metal to the desired dimensions, you can use a wire wheel or brush to clean off the mill scale at the weld locations. Moreover use wood clamps and some wood blocks to hold the materials in place for welding.

Step 3: Layout and Welding

Prepare the layout for your truck bed, which is very simple. The 4 rectangular tubes are welded at the corners. You will find the angle iron clamped in place using a scrap piece of wood along with some miscellaneous clamps welded to it.

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Align all the angles in place horizontally and using wood blocks, level the new bed in place over the frame. Use wire wheel and grinder to clean the rusty truck frame at the weld location.

There are 6 pieces of 10″ long 2″ angle, which you will find welded to the frame of the new flat bed and to the frame of the truck. Make sure to check the distance between the rubber stop that keeps your rear axle from hitting the frame.

You should get clearance from the bottom of the new flat bed, which should be greater than the distance between the stop and the axle. By doing this, you will ensure that your tires won’t ever rub on the new flat bed.

After completing all the tack welding, clean the slag from the welds and then go through following the right procedure and weld each joint with a finish weld. Do all these systematically following the procedure so that the heat does not warp the metal of the new frame.

After you have completed the welding, clean off all of the slag and spatter with the help of a grinder or wire wheel. Wipe down the new frame with a little alcohol. Now you are ready to paint and the wood deck.

Step 4: Cutting and Attaching the Lumber

Measure out all of your lumber and cut each piece down approximately to six feet. Use standard lumber widths to make it easier to replace the boards if needed. Then on either end of each board drill two 5/16″ holes and securet the wood with 5/16″ carriage bolts.

Step 5: Painting and Finishing the Frame

You can purchase a few cans of black spray paint and painted a few coats just to paint the metal that will prevent it from rusting. Make sure you clean any surface rust carefully before painting. Apply several thin coats waiting at least for about half an hour in between coats.

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After the paint dries, bolt the wood deck back down. Drill the holes first so that you can get paint into them and hopefully delay rusting.

Step 6: Attach the Tail Lights

You can use regular trailer lights and just wire them into the existing trailer light wiring harness. You can leave the factory light harness alone.

To attach the tail lights, you have to drill two holes on the bottom of the 2″ x 4″ rectangular tube and attach the lights.

Then you need to strip and connect the wires to the trailer light harness of the truck; attach black wire to black, white wire to white, yellow wire to yellow and green wire to green.

If your truck does not have a trailer light harness, you can just mount the old tail lights horizontally under the flatbed or install a trailer wiring harness.

You can plan to build a headache rack and possibly some removable sidewalls for having protection in rainy season, but for the summer the truck is ready to go.


If you want to save a few bucks on building your own flat bed, you can follow the above steps and do it yourself without taking a professional mechanic’s assistance. This will save other expenditure including mechanic and labour charges. But before doing it on your own, you need to arrange the material and required tools along with the safety measures so that you finish building a flat bed without any hassles.So by now, you have a clear idea on how to build a flatbed truck bed.

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