How to Build a Trundle Bed (Detailed Plans and Video)

Let’s build an easy, beginner-friendly DIY trundle bed using lumber from the big box store. Follow step-by-step with the tutorial, plans and video.

I just finished building a twin bed for my daughter. One of her requests for her new bed was that I add a trundle… because sleepovers are so much fun.

So, I did what any good woodworker mom would do… I built her a trundle to go under the bed.

This trundle bed was easier than you can imagine! It is essentially a box with casters that goes under the bed. You just have to build it to the correct size. I think the hardest part of the project for me was figuring out the correct height for the casters and how to attach them. But lucky for you, since I have figured it out, I will tell you exactly what you need to do.

See how to build the Twin bedframe and headboard here.

DIY Trundle Bed Design

Since the trundle is designed to go under the twin bed, you want to make sure that there is enough space for the trundle AND the mattress to slide in easily.

Be sure to measure your mattress and modify the plans accordingly. If you are building this trundle to go under an existing bed, you can also use bed risers to raise the bed to make space underneath for the trundle.

The bed has a 10.5″ opening underneath, so I used a 1×10 board for the front of the trundle and 1×8 boards for the other three sides. I did route the front of the trundle to make a round edge to make it easy to pull out and push in. But you can also add metal pulls to the front.

Most trundle bed designs I saw on the internet used a sheet of plywood for the bottom. I do not have a car large enough to transport that size of plywood. Plus, I wanted to keep the design simple and not too heavy. So, I designed it pretty much like the bed – with rails and slats.

The heavy-duty casters need to be selected such that they are only slightly visible underneath the trundle. This will maximize the space under the bed, making easy to push it in and pull out.

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How to Build the Trundle Bed

As always, I have the full video for you to watch me build the project step by step. The full written details are below.

Step 1: Prepare the Lumber

• Make the cuts per the cut list in the plans. I highly recommend using a miter saw to make the cuts because it is easy to make accurate cuts. However, a circular saw works well too.
• Sand the boards down. See how to sand wood using the right sandpaper sequence here.

Step 2: Make the Pocket Holes

• Make pocket holes as shown in the plans using a pocket hole jig. The setting for the jig and the drill bit collar is ¾″.

See more about pocket holes and how to make them here.

Step 3: Build the Trundle Bed Frame

• Start by building a box by attaching the two short sides to the two long side using wood glue and pocket hole screws. Make sure to use clamps and a speed square to keep the corners perfectly square.

• Attach the supports to the middle of the box. These will help add sturdiness to the trundle as well as give us supports to add the slats. You will notice that the plans show a different configuration of supports. This is because I realized that modifying the supports will make it easier to attach the casters.

• Add the 2×2 support rails on both ends of the trundle using wood glue and 2″ wood screws.

Once the trundle frame was built, I used the palm router and ¼″ round-over bit on all edges. On the front 1×10 board, I used the palm router on both sides making a rounded edge. This will help push and pull the trundle easily. Alternatively, you can also add a couple of pulls to the front.

This pretty much completes the main build of the trundle bed.

Step 4: Finish

This is a good time to apply the final finish.

• Start by filling in any visible pocket holes. I used a dowel to fill the pocket hole. This is my go-to technique for filling pocket holes.
• Stain or paint in the color of your choice. I painted the bed in Alabaster by Sherwin Williams to match the twin bed.

Step 5: Attach the Casters

• Attach 2 ½″ casters to the underside of the trundle bed.

Picking the casters and figuring out how to attach them was probably the most time-consuming part of this project. I ended up going with 2 ½″ casters with bolts, torq washers and lock nuts.

I did end up adding extra pieces of plywood/boards to make space to add the casters. This is already accounted for the in the updated printable plans.

Step 6: Add the Slats

• Lay down slats in the bed and attach using 1 ¼″ wood screws.

I used a bunch of cut-offs leftover from other projects like the shelf from the closet makeover for the slats. Always better to reuse than buy new wood!

That is it!

The trundle bed is ready. You can add a mattress and bedding and roll it under the bed. I am happy to report that my daughter loves it!

You do need to be careful when rolling it in and out. If you pull/push more from one end, it will be crooked and get stuck at the leg of the bed. The key is to push/pull it in the middle with even force from end to end. It took me 2-3 times but now I can pull/push it easily.

See how to build the twin bed here.

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