How To Replace Particle Board Under Sink (5 Easy Steps)

One of the greatest drawbacks of kitchen cabinets is that they use particle board for the floor below the sink. The choice of material isn’t random; manufacturers use it because it retains screws better than plywood and is less vulnerable to expansion and contraction. While these are obviously positive traits, particle board has one big disadvantage – it is susceptible to moisture and easier to damage than plywood. If you don’t want mold and mildew in your kitchen, you’ll have to replace it.

The easiest way to replace the particle board under the sink is to cut off and remove the central part of your cabinet’s floor, then use a pry bar to remove the edges. You can then install a new particle board cabinet floor or switch to a more durable option.

How To Replace Particle Board Under Kitchen Sink

Things You Will Need

Now, if you’re convinced to give it a try, gather the tools and materials below.

  • Plywood
  • Wooden shims
  • Wooden screws
  • Sandpaper
  • Sander
  • Caulk
  • Caulk gun
  • Pry bar
  • Circular or reciprocating saw
  • Wood saw blade
  • Hammer
  • Wood studs
  • Vacuum cleaner
  • Bucket
  • Pliers
  • Tape measure
  • Protective equipment

Have you gathered everything you need? It’s time to roll up your sleeves and get to work.

1. Gain access to the cabinet bottom 

The under-sink cabinet can serve many purposes, but most of us use it to store cleaning supplies, shopping bags, and other junk stuff.

Miscellaneous items aside, the drain pipes and P-trap could also make the space feel cramped. Gaining access to the floor is crucial.

To do this, remove all items from the cabinet. Then, if necessary, turn off the water, place a bucket under the P-trap, and remove it by unfastening the ring nuts holding it in place.

2. Remove the particle board 

The easiest way to remove a cabinet’s bottom is by removing its center first and then the edges. Simply cut a square in the middle of the board, as close as possible to the edges. Remove this piece, then use the pry bar to lift the edges and remove them.

If the cabinet’s bottom is screwed in place rather than nailed, remove the screws first with an electric drill driver. You may be able to lift the edges at this point, but if they were also glued, you might still have to use the pry bar.

3. Measure and cut the new board 

Once you’ve removed the entire floor, grab the tape measure and measure the exact width and depth of the cabinet’s interior.

Make sure to measure all four sides, as some cabinets aren’t perfectly straight. When you have the numbers, get a ruler and mark the section to cut on your plywood sheet.

Use a circular or reciprocating saw and a wood blade to cut the new floor. Sand the edges to remove all burrs.

4. Install the new cabinet floor

If you managed to remove the old floor without damaging the studs, you could proceed to install the new board. Otherwise, install a few wood studs on all sides and fasten them with screws or nails.

Then, place the new cabinet floor on top of them and screw or nail it in place. When you’re done, sand the entire surface and apply a protective topcoat.

5. Install the P-trap 

If you’ve removed the P-trap, wait for the topcoat to dry (as instructed on its package, but generally about 4-16 hours), then install the P-trap.

Use new washers and tighten the ring nuts properly to prevent future leaks. Turn on the water and let the sink run for a few minutes. Use a paper tissue to check for minor leaks around all plumbing joints. If everything’s dry, you can start enjoying your new cabinet.

3 Reasons Why You May Have To Replace Cabinet Floor Under Kitchen Sink

Particle board may not be as resistant as plywood, but the material is incredibly resilient. It usually swells when it comes in contact with water, but you may be able to repair the damage if you spot it in time. Moreover, most kitchen cabinet floors are covered with a sheet of laminate which prevents water from soaking into the board. That said, there are moments when you can’t fix water damage. Check them out below.

1. Extensive Signs of Rot

Like most wooden products, the particle board will rot when it gets wet frequently. Thus, if your sink leaks and the cabinet’s bottom is constantly damp, you can expect the particle board to rot. Some of the most common signs include:

  • Warping: One of the most common particle board rot signs, warping happens when water seeps around the edges of the plank, leaving the middle of the board dry. 
  • Swelling or shrinking: We all know that wood swells when it is constantly exposed to moisture, but not many people know that it can also shrink. Thus, both swelling and shrinking are signs of a rotten particle board. Shrinking usually happens when the plank is exposed to the water intermittently and then dries completely before getting damp again. Swelling is often a sign of constant exposure. Shrinking is almost always accompanied by cracks.
  • Disintegration: If the particle board isn’t sealed properly, water can infiltrate and keep the material damp. This creates the perfect environment for a variety of fungi and bacteria to grow. These microorganisms accelerate the decomposition process, causing the cabinet’s bottom to disintegrate slowly.

2. Mold and Mildew

Mold and mildew can grow in your kitchen for a variety of reasons, but when you spot the dark stains inside the cabinets, you can rest assured it’s almost always due to excessive moisture. 

Plumbing leaks aren’t always easy to detect. Moreover, your cabinets might also suffer from a high level of humidity in your home. 

If the cabinet’s bottom is moldy and looks damp or badly stained, you should replace it immediately. Like most germs, mold and mildew can cause asthma attacks in sensitive subjects and could contribute to the development of respiratory diseases and other airborne infections.

3. Weakened Structure 

Lastly, you should replace the particle board if the structure has weakened. Otherwise, it could break and damage any fragile items you store under the sink. Not only that, but a broken cabinet floor can also weaken the rest of the cabinet’s structure, which may collapse under the sink’s weight.

Before You Start Replacing Sink Cabinet Bottom

Replacing the sink cabinet bottom is the perfect project to tackle if you’re a beginner. Woodworking projects are almost always the most approachable. However, whether you decide to replace the cabinet’s bottom yourself or hire a pro, here are a few things to know before starting.

How much does it cost to replace the board under the sink?

Replacing the particle board under the sink is cheap no matter how you decide to tackle the project. Hiring a contractor will rarely cost you more than $300 for labor and materials. If you find this amount on the expensive side, you can replace it yourself.

There are various material options to choose from, but your best bet is birch plywood. This is one of the most resilient materials you could use, even if you might struggle to drive the fasteners through it. A 4×8 sheet of 5-ply birch costs about $44.97. Cheaper plywood can help you save even more; a sheet of the same size rarely costing over $25.

The power tools you may have to employ are expensive to buy, but you can rent all necessary equipment for under $100 per day.

Frequently Asked Questions

Replacing the sink’s cabinet floor is as easy as pie, but you may still feel overwhelmed and full of questions. Here are some answers.

What kind of wood do you put under a sink?

Birch ply is the best wood to put under the sink. While cabinet makers use particle board for its lower cost and higher screw retention, birch plywood provides excellent water resistance, and it will last significantly longer.

You should always protect the wood with a top coat after installing the new floor. If you want, you can even go as far as gluing a sheet of laminate or PVC on the board to prolong its lifespan.

What is the difference between a base cabinet and a sink base cabinet?

The main difference between a base cabinet and a sink base cabinet is the lack of drawers or shelves in the sink cabinet. The empty space inside the cabinet is designed to prevent drawers or shelving from interfering with your plumbing.

However, sink cabinets may still have drawer fronts on them. These fronts aren’t connected to actual drawers but are only glued to the cabinet’s frame for aesthetical reasons. They are not functional but maintain a visual unity between the sink cabinet and the rest of your base units.

Next Steps

The particle board under the sink can get damaged easily, but you don’t have to buy new cabinets. Replacing it is a cinch, and this project is more than suitable for beginners. If you’re not confident enough to give it a try, you can always hire a professional.

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