DIY Under Sink Cabinet Storage Idea for a Small Bathroom

When you have a small bathroom with limited counter space and need to maximize storage, you may be tempted to run to the container store or your local big box store to buy some cheap plastic storage solutions. But, oftentimes you end up with more wasted space and less money. Instead I’m going to show you how to create your own custom sink organizers with a custom drawer unit and a shelf using inexpensive storage bins from the dollar store and some scraps of wood. Plus, we’ll take advantage of vertical space and offer you the best solution for storing everything in a limited space. Sound good? Read on to learn how to make these DIY-friendly under-sink storage solutions.

DIY Under Sink Cabinet Storage Idea for a Small Bathroom

Our downstairs powder room may not be a primary bathroom, but it has to function as storage for cleaning supplies, bathroom essentials, toilet paper, extra soap, hand towels, and other small toiletries. Recently, I got fed up with the mess in the sink cabinet and decided to use up some of my wood scraps in the shop and create better storage in the limited space.

Measure Under Your Sink

To begin you’ll need to take the measurements inside your sink vanity. Empty everything out from the under-sink area. Measure the width, depth, and the height. Then make note of where your sink drain pipe extends down. Now decide where enough space exists for some plastic drawers or shelving.

Plan Your Storage Needs:

Assess your storage needs and search for a few bins that will work ask storage drawers under your sink. Chances are you may already own bins or baskets that will work for this project. You will need to make sure they have a lip along the top of the bin in order for this storage solution to work. But, you could also alter the plans and create a little shelf unit instead.

If you don’t have bins already, you can definitely purchase inexpensive bins from the dollar store (or a yard sale, thrift shop, or Walmart.) I purchased all three of the clear storage bins above from the dollar store for $4.83 total! If you don’t have a Dollar Tree near you, these are similar to the ones I bought.

Materials, Tools, & Supplies

(I’ve included affiliate links for your convenience. I earn a small percentage from a purchase using these links. There is no additional cost to you. You can read more about affiliate links here.)

Plastic Bins with a lip
Scrap Plywood:
- 1/4″ for the back
- 3/8″ for the runners
- 1/2 or 3/4″ for the sides
Wood glue
Brad Nails
Miter Saw
Nailgun (optional)
Wood Screws
Drill

Instructions to Build Custom Under Sink Storage Solutions

A great way to assess your cabinet space is to draw up plans using your cabinet measurements before you begin. For simple builds, you can use pencil and paper. For a more complicated build, try using a program like SketchUp.

Drawing Plans for Your Storage Cabinet

Keep in mind, you’ll need two sides (3/4″), a top (3/4″), back (1/4″), and slats (1/4 – 3/8″) to act as runners for your storage bin drawers. (A quick note about rip cutting your scrap wood: you can use a table saw, band saw, track saw, or a circular saw with this DIY jig to rip cut your plywood down.)

Now let’s start measuring your bins. Measure the depth, width and height of your plastic bins.

The depth of the bin will the exact depth of your DIY cabinet box (before adding the back.) The width of my bins is 8 11/16″, but I’ll add 1/16″ to keep them from being too tight when pulling them in and out of the under-sink storage cabinet. Therefore the interior width of my storage cabinet needs to be 8 3/4″.

Next, I’ll measure from the base of the plastic bin to the underside of the lip. Add 1/8″ to this measurement (or throw a piece of cardboard underneath the bin like I did).

(i.e. My bin lip is 4 5/8″ with an added 1/8″ space, this equals 4 3/4″. This will be the location for the top of my bottom bin runner slat.)

For the design of my storage drawer cabinet, I chose to leave a 3/4″ gap between the bins to keep space between the items inside and the bin above it.

Your measurements will vary, but based on the bins and my design idea, my mini storage cabinet is 16 1/4″ tall x 12″ deep x 10″ wide. I chose to use 3/8″ plywood ripped to 3 1/2″ and cut to 12″ in depth. You could use 1/4″ plywood for the runners, just make sure the inside of your cabinet box is no more than 1/8″ wider than the bins’ width.

Cut and Mock Up Your Storage Cabinet Pieces

After making sure your storage drawer cabinet will fit in the horizontal and vertical space in your bathroom cabinet, cut your scrap wood per your plans.

My cut pieces are shown below. You’ll notice my top piece is made from two pieces. Ideally, you would use one piece, but I was using up my scraps.

Now that you have your pieces cut, you can go an extra step and create a mock up for the storage drawers before assembling them.

Looking good? Okay, now sand all your edges smooth.

Assemble Your Storage Cabinet

Grab the two side pieces and your slats. Mark the location for the top of your bottom bin slat.

Add glue to the back of the slat and then nail it in place. Repeat the steps for the remaining slats. (Remember I chose to leave 3/4 gap between the bins. So my first slat top was positioned at 4 3/4″ height. The next slat was secured at 4 3/4″ + 3/4″ = 5 1/2”.) You’ll notice I positioned both sides next to each other to insure the slats were positioned at the exact same height.

Your two sides should look like this:

To attach the top, layout the sides and set the top in place. (I chose to add my top between the sides, but you could add it on top of the sides as shown in the computer model below.) Secure the top to the sides with wood screws. Be sure to pre-drill before driving the wood screws in to prevent splitting.

If Using Screws: Pre-drill & Screw Top Between the Sides

Test fit your plastic storage bins before adding the back.

Measure the back of your cabinet. Cut your 1/4″ plywood to size and test the fit. Add glue along the back edges of your cabinet. Then secure the back with nails or screws (pre-drill before using screws.)

Set Your New Custom Under Sink Storage Drawers

Slide your plastic drawers into the cabinet box. Set it underneath the sink and load it up! This is a great spot to corral all those small items or things that you don’t want getting wet if there was a leak.

I hope you found this idea for tiny bathroom storage ideas super helpful. This can work in almost any bathroom cabinet or other storage cabinets that need more cabinet space or as an ideal solution for your family members who are sharing one bathroom.

But, wait, there’s more! I’m going to show you how to build a little custom shelf for the tight spaces on the other side of the cabinet. Hey, we might as well claim as much extra space as we can, right?!

Building a Custom Under Sink Cabinet Shelf

For this custom shelf, you’ll need a few more pieces of scrap plywood. 1/2″ – 3/4″ thick plywood should work fine. I just happen to have a lot of 3/4″ scraps. Start by measuring the width between your new storage drawers and the side of the cabinet. Be sure to deduct for a face frame if your cabinet has one.

Cut the top of your scrap plywood to this length. Then cut two vertical pieces to support the shelf (be sure to factor in the height of your plumbing and deduct for the thickness of your plywood shelf.

Add a bead of glue to the tops of the legs. Then square up the top on the legs. Secure with nails or screws.

If you prefer a more finished look, you can cover the plywood edges with edge banding following this simple tutorial.

Set your new shelf in place next to the storage drawers.

If your storage cabinet and shelf are too tight to fit beyond the hinges, you may have to remove one of the doors to get them inside the cabinet.

What do you think? Can you believe this is the same sink cabinet? The custom storage solution is much better for keeping all our supplies within easy reach.

These under-bathroom sink storage ideas are also a great solution for smaller items like hair products, hair tools, or other beauty products. This DIY custom storage easily doubled the storage space, don’t you think?

Hope you’ll stick around for more DIY ideas to make your home more functional.