Can You Fix Water Damaged MDF?

By thewriteDuffy •  Updated: 11/10/21 •  12 min read

Budgets can be difficult and unforgiving. Just as unforgiving and difficult is water damage done to pieces that you want to keep in your home like your kitchen cabinets, which would be expensive to just replace.

So, can you fix water damaged medium-density fiberboard (MDF)? If the damage is not extensive, meaning the MDF hasn’t warped, crumbled, or separated from itself you should be able to repair it. But some items like baseboards, or items that have been exposed to water for a long time may not be possible to repair and your best solution may be just to replace them.

I’ll cover how to fix most water-damaged MDF bathroom or kitchen cabinets and baseboards below, but first, we need to make sure that’s what we’re trying to do.

Please note that some links in this post are affiliate links meaning we will receive a small commission if you make a qualifying purchase through one of those links (at no additional cost to you).  Read the full disclosure.

First, is it Really MDF?

First of all, it’s important before doing any repairs that you’re sure of what you’re dealing with so you’re using the right tools and method. What is MDF?  Short for Medium-Density Fiberboard (another name for pressboard), MDF is sawdust and resin formed into moldings, baseboards, or other boards like cabinets. 

MDF is very susceptible to water damage and moisture will cause it to bubble and become swollen.

Medium Density Fiberboard (MDF) vs Particle Board

When looking at it unpainted MDF looks like solid cardboard, not like wood chips, which is particle board. Here’s a quick visual:

Top Board = MDF; Bottom Board = Particle Board

MDF has a much crisper edge than particleboard since it’s made from very small wood fibers, almost like flour, while particleboard is made from larger, coarser fibers. Particleboard tends to chip when being worked with, especially after water damage, so it’s important to note which material you’re hoping to repair.

MDF Isn’t Used Just to Save Money

When figuring out what material you’re working with, don’t assume that MDF is only used in cheaper applications or inexpensive homes.  We’ve seen plenty of million-dollar and multi-million dollar homes with MDF trim and baseboards.  MDF is consistently smooth and uniform and doesn’t have any knots or dark spots, so it’s also an aesthetic choice for many builders and homeowners.

How TO Fix Water-Damaged Cabinets

If the water damage is made to your MDF cabinets, whether kitchen cabinets or bathroom cabinets, you’re likely able to repair it if it hasn’t become so damaged it has severely warped, crumbled apart, or split, here’s how:

Step One: Dry Out the MDF

Can you dry out MDF? Yes, you can! MDF can be dried out if it hasn’t been exposed to water for a very long time just by first drying it off with some rags or paper towels as quickly as possible, opening up all the affected cabinet doors or drawers, and then either setting up fans to move as much air as possible over the damaged area or by using a heat gun (or hairdryer if you don’t have a heat gun).

If you’re using a heat gun or hairdryer, pass it back and forth over the wet cabinets, making a pattern like you’re mowing a lawn, back and forth in alternating directions as you move along. You want to dry the boards quickly but evenly so as not to warp them even more than they may be already.

Step Two: Remove any Hardware Determine the Extent of the Damage

Once the cabinets are dry you can remove any hardware in the way and assess the extent of the damage and see what your next steps will be. If the damaged area looks like it can be sanded down to a smooth even finish, and you’re able to match your cabinet’s paint, you should be able to do a spot repair.

However, if you’re unable to match your cabinet color, you may need to both repair the damaged area and refinish your entire set of cabinets.

The following steps assume you’re simply fixing a small damage spot, but if you are stuck refinishing your entire set of bathroom or kitchen cabinets you’ll just need to follow these steps for the repair, and then take the added step of sanding down all of the remaining cabinets and drawers, wiping all the surfaces clean with a tack cloth, and then priming and painting them all as well. This will of course be the only to get a uniform, even finish across all the cabinets and drawers, if that’s the look you want.

Step Three: Sand Down and Fill the Damaged Area Until Smooth

Use an orbital sander and some 120-grit sanding disks; or a sanding block with some 120-grit sandpaper sheets to sand down the damage. An orbital sander will be your best option for this as it will get a more even finish and go much faster.

If there are any small holes or knicks, this is the time to fill them with some white wood filler. After the filler has dried, lightly resand it to make a smooth, ready-to-paint surface.

Step Four: Wipe Clean and Prime

After all the filling and sanding is done, wipe down the cabinets with a soft tack cloth to remove any dust and debris caused by the sanding.

Once clean, prime the MDF cabinets with a shellac primer, I like to use a priming spray for even, light coverage. The shellac base will not rehydrate the MDF as a water-based primer would. This type of primer will help protect it against future damage.

Step Five: Paint And Re-attach Hardware

Once everything is smoothed and primed, all that’s left is to paint over the cabinets and re-attach any hardware you removed for the fix.

Tools You’ll Need for MDF Cabinet Repair

  1. An orbital sander and some 120-grit sanding disks (like these Gator brand ones) or. For occasional minor repairs, an inexpensive orbital sander will do just fine and last you for years. This 5″ Black and Decker corded sander for example is pretty inexpensive, the perfect size for small repairs, and very easy to use even if you’re not used to power tools. If you don’t have an orbital sander and this is literally the only time you think you’ll use one, either borrow one or just use a … Just note using an .. will cost you much more time and elbow grease.
  2. Wood filler, if needed. This small tube from DAP should be plenty.
  3. A shellac-based primer. This Zinsser shellac-based primer spray works well and should be plenty for up to a handful of kitchen cabinets.
  4. Paint in the color of your cabinets. If you can’t match your existing cabinets and need to refinish all your kitchen or bathroom cabinets, I did have great success with Rust-Oleum’s Transformations Cabinet Refinishing Kit. I used it in ivory to refinish an entire kitchen and loved the customization and look. They also have a variety of colors that make sense for a kitchen, and clear instructions, so it takes some of the guesswork out of it.

How To PROTECT KITCHEN CABINETS FROM Future WATER Damage

If you want to protect your cabinets from future water damage you may want to laminate them. Laminating cabinets consist of applying a smooth, water-resistant material to the exterior cabinet walls and doors. Laminating is an effective way to protect cabinets and change the look of your kitchen or bathroom, but know that it doesn’t fully waterproof the cabinets.

The following tips also help protect kitchen cabinets from water damage.

How TO fix water damaged MDF baseboards

If water damage occurred to your baseboards, moldings, or trim things can get a bit trickier since there are often some complicated routed details on baseboards and there’s direct contact with your drywall.

If the water damage is not significant, and the swells can be sanded down, you can attempt to repair MDF baseboards by removing them and repairing them following these steps (a list of tools you’ll need is also further down below if you’re missing anything, or want a complete list):

  1. Cut: Run a sharp utility knife along the top inside edge of the damaged baseboard and down any corners.
  2. Pry: Carefully pry it off with a small steel pry bar with a scraper edge.
  3. Sand: Use an orbital sander and some 120-grit sanding disks; or a sanding block with some 120-grit sandpaper sheets to sand down the damage. An orbital sander will be your best option for this as it will get a more even finish and go much faster.
  4. Fill and Re-sand (If needed): If there are any small holes or knicks, this is the time to fill them with some white wood filler. After the filler has dried, lightly resand it to make a smooth, ready-to-paint surface. If you don’t have any holes or knicks, just skip this step.
  5. Clean: Clean the surface with a paper towel or tack cloth to remove any sanding dust, leftover calking, or other dirt and debris.
  6. Prime: Prime the baseboard with a shellac primer, I like to use a priming spray for even, light coverage. The shellac base will not rehydrate the MDF as a water-based primer would and will help protect it against future damage.
  7. Seal It (Optional): Seal the bottom of the baseboard with a thin coat of white kitchen and bathroom calking. If you take this extra step to prevent future repairs if it gets wet again, you’ll then want to lightly sand it smooth again, wipe it clean with a paper towel once again, and then apply a coat prime to it one more time.
  8. Reinstall: Nail the baseboard back in place.
  9. Fill & Seal: Fill your small nail holes with 3M patch plus and use white calking (be sure to get white, clear sounds good in theory but it always turns yellow over time) to seal the baseboard edges. Some choose to use calking for both the nails and seals, but it tends to shrink a bit, so depending on the nails you choose, once the calking shrinks it can leave some small dents.
  10. Paint: Paint the baseboard with your usual baseboard paint.

Reading the steps is one thing, but here’s a quick video by The Funny Carpenter showing you the same basic steps as I’ve laid out here.

Tools You’ll Need for MDF Baseboard Repair

  1. A Utility knife.
  2. A Small pry bar scraper-edge tool.
  3. An orbital sander and some 120-grit sanding disks (like these Gator brand ones) or. For occasional minor repairs, an inexpensive orbital sander will do just fine and last you for years. This 5″ Black and Decker corded sander for example is pretty inexpensive, the perfect size for small repairs, and very easy to use even if you’re not used to power tools. If you don’t have an orbital sander and this is literally the only time you think you’ll use one, either borrow one or just use a … Just note using an .. will cost you much more time and elbow grease.
  4. White wood filler, if needed. This small tube from DAP should be plenty.
  5. A shellac-based primer. This Zinsser shellac-based primer spray works well and should be plenty for any small to medium sized repair.
  6. A sanding sponge of 120-grit or less. I like these 3M fine-grit ones for projects like this.
  7. White kitchen and bathroom calking. This Red Devil one works just fine for this, just again, make sure to get white as clear will always turn yellow over a few years.
  8. 3M Patch Plus. Again, this is being a bit fussy, but this really works better at filling the nail holes and making them blend in seamlessly.
  9. A finishing nail gun and 6d (2’’) or 8d (2.5’’) 16-18 gauge nails. A nail gun is a major purchase in my opinion (it took me weeks to choose a finishing nailer to gift to Dan one Christmas), so we are testing out a few and working on a proper guide to help you choose one; but if you want my quick recommendation based on our current experience, go with the DeWalt 20V Cordless Brad Nailer Kit, we LOVE it! It works on standard DeWalt batteries so it’s easy to use because there’s no hoses and it’s lightweight. Better yet, it’s 18 gauge and depth adjustable, so it’s perfect for jobs like trim. It doesn’t eat batteries either, we’ve never done trim fast enough to complete a house in one shot, but you could probably do a whole house of baseboards on a small battery without a charge.

Removing and Replacing MDF Baseboards

As you can see from my lengthy instructions and shopping list above unless you have a fully stocked garage of products, and a great deal of time, the cost in both time and money to repair water-damaged MDF baseboard can be much more than just replacing it.

Here’s a quick video from The Do Good Project showing you what baseboard replacement looks like.

thewriteDuffy